[HN Gopher] Bicycle
___________________________________________________________________
Bicycle
Author : todsacerdoti
Score : 1289 points
Date : 2023-03-28 16:19 UTC (6 hours ago)
(HTM) web link (ciechanow.ski)
(TXT) w3m dump (ciechanow.ski)
| wiredfool wrote:
| This is a really impressive article -- he went quite far into the
| physics of bikes and wheels and didn't say anything that I could
| point to as being wrong.
| martopix wrote:
| Fantastic for teaching high school physics
| sha-3 wrote:
| Great, this is the best way start the day!
| lom wrote:
| I'm not even done with reading, but i've been very interested in
| bikes and how they work for quite some time now and I can
| confidentially say that this is on of the best writeups there is.
| Thanks to the author for making this
| nntwozz wrote:
| Immediately made me think of Steve Jobs and this great clip:
|
| "Computers are like a bicycle for our minds."
| https://youtu.be/ob_GX50Za6c
| dejawu wrote:
| And its counterpart quote by Bill Gates, "Bicycles are like a
| computer for our legs."
| eDameXxX wrote:
| I see new post from Bartosz, I upvote. Simple as that.
| marai2 wrote:
| Pshh, I know how to ride a bicycle, why is ciechanowski writing
| an article about riding a bicycle?!
|
| Holy moly!! I didn't realize I didn't know how I actually ride a
| bicycle!!
|
| Obligatory sound track for this excellent post:
|
| https://youtu.be/KwvWtZl2ICY
| JALTU wrote:
| Dang, you beat me to it, I was busy inflating my tires to 120
| psi.
| samstave wrote:
| Go tubeless!
|
| https://youtu.be/skW_Ysew3zw
| exabrial wrote:
| When I first started MTB in 2020... I tried to inflate my
| tubeless rear tire to 60psi once, because that was the "max
| pressure" written on the sidewall.
|
| There are times you are incorrect, and wow, there are times
| you are very very wrong. They should make tubeless sealant
| in blood red just for fun.
| flavius29663 wrote:
| You probably know this...but the song is not about a literal
| bicycle...it's about Freddie being "bi". I only say this
| because it took me too long to realize that.
| NickC25 wrote:
| This guy's content is seriously top notch. His recent article on
| Sound from a few months ago was _astounding_ and probably the
| best article I 've seen posted here.
| adverbly wrote:
| I always find it interesting to think about bicycles and just how
| recently they were invented.
|
| Compare bicycles with steel making, for example. Steel making
| happened thousands of years ago. The modern bicycle was what -
| under 200 years ago?
|
| Bikes seem like such a primitive technology, and yet as this
| article demonstrates, it takes a lot of engineering to design
| even primitive products.
|
| It makes me wonder how many other simple or primitive products
| are out there which have yet to be discovered.
| alt227 wrote:
| Bicycles are a relatively new invention because they require
| roads/flat paths which are also a relatively new occurance, and
| came about due to the widepread use of horses and then
| carraiges for transportation.
|
| A bike at any other point in human history would have been
| completely useless trying to traverse natural terrain.
| PaulDavisThe1st wrote:
| The modern "fat bike" would be (is!) quite good at traversing
| a variety of natural terrains where humans live, without
| roads or paths/trails.
| ejensler wrote:
| Agreed. Bicycles are kind of a miracle of seeming simplicity
| hiding a ton of important developments of the industrial age.
| 99 Percent Invisible did a recent episode on just this topic:
| https://99percentinvisible.org/episode/the-safety-bicycle/.
| cainxinth wrote:
| I always loved the scene in HBO's Deadwood when the first
| bicycle comes to town and everyone gathers to watch someone try
| and ride it.
| blululu wrote:
| A parallel thought is that the first airplane is the product of
| bicycle mechanics and not railway or automotive mechanics. As
| others pointed out, there are a lot of necessary technologies
| like rubber, bearings, lubricants, sprockets and chains that
| need to be developed, but there is also something very elegant
| about bicycles. If you start to mess around with a 70's era
| road bikes you get a sense of just how perfectly everything
| needs to fit together and how everything affects everything
| else. (You see it more clearly in older bikes because you need
| to deal with non-standard parts). I think I learned more about
| bicycles from the royal pain of a 1982 Peugeot than anything
| else. This is not to say that a car doesn't have similar
| complexity, but the use of chemical fuel and 4 wheels masks how
| the tunings fit together. With my current bike there is a
| serious difference when it is perfectly tuned.
| atoav wrote:
| A thought:
|
| The invention of the bicycle came at a similar time like engine
| driven vehicles. _Before_ those became popular, the direct
| competitor for bicycles (one person transportation) were
| horses.
|
| There might have literally not been a need to invent a bicycle
| as horses fulfilled the same purpose and had the advantage that
| they fared better on the back then nearly non-existent
| infrastructure.
|
| Also: a single person transportation vehicle was not something
| a lot of people _needed_ in their lives. You needed something
| to move stuff, but the demand to move single people daily came
| into existence with the dawn of big cities.
| odd_perfect_num wrote:
| It takes a LOT more calories to power a horse than a biker.
| atoav wrote:
| On a cretan mountain path with before christ technology?
| bluishgreen wrote:
| No shit, you can make an airplane if you know your way around a
| bicycle as the wright brothers demonstrated. They were bicycle
| mechanics originally.
| otabdeveloper4 wrote:
| Ball-bearings? Primitive?? Surely you jest!
| jodrellblank wrote:
| Bikes benefit a lot from pneumatic tyres, pressure pumps,
| smooth asphalt (not cobbles), precision engineering of chains,
| chemistry of oils and lubricants, rust-proof steel, rubber
| brake pads with compounds that last long enough and resist
| rain, spring steel for suspension, cables that don't stretch.
| Without those things you get a wooden boneshaker hobby-horse,
| large, heavy, energy inefficient, incovenient:
| https://duckduckgo.com/?q=hobby+horse+victorian+bike&t=ffab&...
|
| (And internal combustion engines; how are you going to
| distribute them around the Roman Empire by the tens of millions
| without trucks or ships?)
| throw0101b wrote:
| > _Bikes benefit a lot from [...] smooth asphalt (not
| cobbles)_
|
| Bicycle riding societies were some of the more vocal
| proponents on paved roads (predating the automobile):
|
| * https://www.vox.com/2015/3/19/8253035/roads-cyclists-cars-
| hi...
|
| * https://www.theguardian.com/environment/bike-
| blog/2011/aug/1...
|
| * https://www.smithsonianmag.com/travel/american-drivers-
| thank...
| sharkweek wrote:
| And now of course some of the most prestigious races in the
| professional cycling world are across predominantly cobbled
| roads as a form of torture for those racing.
|
| https://cdn.mos.cms.futurecdn.net/hD4Vtdmow7B4Jf4XiWPH5g.jp
| g
| throw0101b wrote:
| Also lots of competition on non-paved roads:
|
| * https://en.wikipedia.org/wiki/Cyclo-cross
| sharkweek wrote:
| As a former (and not great) CX racer, this sport should
| not be talked about, as it's a cruel beast to those who
| dare and try.
|
| (Kidding, of course, it's a wildly entertaining form of
| racing)
| B1FF_PSUVM wrote:
| Yep, 90% materials, and so are other things like windsurfing,
| paragliding, etc.
|
| Very little of the "modern stuff the ancients didn't figure
| out" could be done without modern materials.
|
| If dumped back in time, maybe you could make rent teaching
| swimming or doing accounting. Medicine would probably be too
| dangerous.
| blululu wrote:
| Yeah. Surfing is a great example of a Stone Age sport that
| has been radically changed by Space Age technology. Koa
| wood gets you a longboard that is hard to steer and can
| only surf long smooth waves. The modern surfboard is very
| much born out of California's aviation industry and its
| fixation on light, strong materials and aerodynamics.
| Surfing Pipeline is only possible with modern plastics,
| fins and shaping.
| Khoth wrote:
| To expand on one of those things - bike chains get slightly
| longer as they wear out. Once it's about 1% longer than it
| started, it looks about the same as it always did, but it's
| starting to damage the drivechain and you need to replace it.
| An ancient Roman blacksmith has no hope of making a chain
| with anything like that level of precision.
| convolvatron wrote:
| you would have used leather belts. it would have been a
| pita, they stretch pretty fast...but its feasible I think.
| flavius29663 wrote:
| You don't have to use chains though, you can have pedals on
| the front wheel, like the original bikes, or not pedal at
| all, just push yourself on the ground
| thinkling wrote:
| I believe you only have this problem if your bike has gears
| based on a set of sprockets (different size chainwheels and
| a derailleur to move the chain from one to the other).
|
| In Europe (Holland in particular), people ride single gear
| city bikes (or internally geared hubs) for decades without
| replacing chains or cogs. When you only have one chainring
| and one cog, they wear along with the chain, and it takes a
| very very long time to encounter problems.
|
| It's when you have the sprocket cluster with multiple cogs
| that are not all wearing equally, that you get problems. Or
| often the problem on geared bikes doesn't appear until you
| replace your worn chain and the new chain no longer meshes
| well with the cogs worn to match the old chain.
| mardifoufs wrote:
| Wouldn't the chain still need to be quite intricate and
| pretty hard to make even then? Though now that I think
| about it, you could probably make it in a way similar to
| chainmail, since tight tolerances aren't actually that
| crucial (the results would suck, but only compared to
| modern bikes). Though the other parts might be just as
| hard to make and especially to fit together (the
| bearings, the gearing for the chains...)
| jen729w wrote:
| Or in any flat hipster city. Melbourne (now Canberra)
| representing!
|
| I ride my single speed (not fixed) every day. It's my
| most beloved possession.
| loeg wrote:
| Yeah. The vast majority of parts on a bicycle are the
| individual links in a chain. Manufacturing these to
| sufficient tolerance is quite challenging.
|
| Romans might have been able to do shaft-drive. Or Penny-
| farthings (direct pedal-wheel drive).
| Alex3917 wrote:
| The key invention that made them possible was ball bearings.
| This is why the modern bicycle and the modern car were
| invented within a year or two of each other.
| alt227 wrote:
| ...and roads, which were created for use by horses and
| carraiges.
| kube-system wrote:
| I guess perspective makes it a lot less surprising that the
| first airplanes were made by bicycle manufacturers.
| samstave wrote:
| You will be amazed to know that the Ball Brothers, who
| invested the Mason Jar/Atlas Jar, and perfected canning and
| soups... is also Ball Aerospace - who makes super-high end
| space components for the MIC, black projects, skunkworks,
| NASA etc...
|
| All from the Mason Jar.
|
| https://www.visitmuncie.org/a-legacy-etched-in-glass-the-
| bal...
|
| (also "Aliens")
| Cthulhu_ wrote:
| Don't even get me started on airplanes though - there was
| only 66 years between the first airplane (Wright Flyer in
| 1903) and the moon landing (1969).
|
| Disclaimer: that's of course a cool anecdote on the surface,
| but rockets have been around since the 13th century so
| they're two mostly different technologies.
| johannes1234321 wrote:
| Are rockets and planes related? Quite different
| requirements regarding aerodynamics and propulsion.
| kube-system wrote:
| It's all the same, just that the density of the fluid the
| vehicle is traveling in changes.
| fiftyacorn wrote:
| The production of quality steel isnt thousands of years old.
|
| Yeah they could produce small items - but to make the steel of
| the quality needed for bicycles is pretty new - the past
| 150-200 years with the Bessemer process
| m3kw9 wrote:
| Surprised that the reason the frame is hollow is for structural
| reason rather than to just save weight.
| auggierose wrote:
| Wow. Beautiful piece of art, but I am not going to read it. For
| someone who has, is the length of the article proportional to the
| gained knowledge, or could that be expressed much more succinct?
| aoeusnth1 wrote:
| If you don't have time to read it, why do you have time to
| comment on it?
| macrael wrote:
| I've loved every article he's done so far. He only publishes
| about once a quarter and usually his articles are ~2 hours
| long. I've yet to be unimpressed.
| tambourine_man wrote:
| If you don't know Bartosz Ciechanowski's site yet, checkout his
| archives.
|
| Be careful if you have deadlines for today though, you may be
| there for a long and awesome time.
| loeg wrote:
| The first animation is sort of wrong. To turn right on a bicycle,
| you actually steer slightly left (and vice versa). It's very
| jarring to see the wheel rotated in the same direction of the
| turn at extreme lean angles -- if you do that in the real world,
| you'll crash.
|
| https://en.wikipedia.org/wiki/Countersteering
| TeddyDD wrote:
| Countersteering is explained later in the article.
| loeg wrote:
| Great. My complaint about the animation stands.
| mazugrin2 wrote:
| No, I don't think it does. Counter-steering is only a
| feature of a turn being initiated. Once the turn is in
| progress, the front wheel will very much be pointed in the
| direction of the turn.
| loeg wrote:
| Based on my experience, I believe that's not true. You
| counter-steer through the turn or your momentum would
| push the bicycle-rider system upright (centrifugal
| effect). Pointing the front wheel in the direction of the
| turn will initiate countersteer in the other direction
| (i.e., getting out of the turn). (I ride bikes most days
| of the year, if that helps.)
| kqr wrote:
| Unless we are talking something like speedway
| motorcycling[1] a constant-rate turn is accomplished by,
| after the initial counter-steering, pointing the wheel in
| the direction of the turn, such that the self-uprighting
| tendency of the bicycle matches the speed at which it
| falls to the ground due to gravity.
|
| If you kept pointing the front wheel to the other side of
| the turn, the bike would fall over. (This property is
| what you use to initiate the turn, but not to maintain
| it.)
|
| [1]: https://3.bp.blogspot.com/-xTxeag2HCjs/WsXXrKRxWrI/A
| AAAAAAAc...
| topaz0 wrote:
| I believe you are mistaken. At steady state turning the
| steering is typically pretty subtle, and of course you
| can oversteer and have that mess with your balance in the
| opposite direction, but some steering has to be there to
| get the wheel to go in the right direction.
| m4lvin wrote:
| If I look at the first animation from the right angle and
| play with the slider then I can see countersteering.
| thomasfl wrote:
| The most important fact is that riding a bicycle is 3 to 5 times
| more energy efficient than walking. Depending on the road,
| bicycle, terrain and weight of the rider. Riding a bicycle is the
| most efficient self-powered means of transportation.
|
| https://en.wikipedia.org/wiki/Bicycle_performance
| Cthulhu_ wrote:
| I had a look and the source cited for it being the most
| efficent self-powered means of transportation is from March
| 1973; I wonder if there's been any new developments since then.
|
| Random things off the top of my head: Some time ago they built
| a self-propelled helicopter, which also used bike technology
| (gears etc). I vaguely recall that people did state that rowing
| is what you should use to get the most energy out of a human
| body - it is (or can be) a full-body motion, including the
| large muscles in the back and legs and the smaller ones in the
| arms, while cycling mainly uses the legs. But the mechanism to
| translate rowing energy into the propellers was too heavy, or
| something like that.
|
| Actually it might have been a HN thread. Here's one from 10
| years ago, and it just so happens that I had made my account by
| then so this was probably it:
| https://news.ycombinator.com/item?id=6028326
| bheadmaster wrote:
| If we take distance passed as a measurement, intuition tells
| me that bicycle is more efficient, since it doesn't have to
| lift the whole body, just move it around on wheels which
| provide very small friction.
|
| Perhaps if we had bicycles with comfortable seats we can
| recline in, we could save up energy needed to balance our
| body on a bicycle. Something like a pedal boat, but with
| wheels.
| AlbertCory wrote:
| Wouldn't that be a simple mod to a recumbent bike?
| bheadmaster wrote:
| Honestly, this is the first time I've heard that word.
| Pretty expected that someone came up with it already, in
| retrospective.
| citrusybread wrote:
| check out velomobile, recumbent bicycles with a
| fiberglass shell that can go crazy fast (60km/h is not
| unheard of).
| vbarrielle wrote:
| 60km/h is sprint speed for elite cyclists on road bikes,
| I guess recumbent bikes can go way faster than that.
| tromp wrote:
| And 144km/h is possible, but only for the world record
| holder:
|
| https://www.cbc.ca/sportslongform/entry/the-worlds-
| fastest-h...
| AlbertCory wrote:
| I see them on the street fairly often.
| simantel wrote:
| Recumbent bikes definitely are more efficient due to
| aerodynamics if nothing else. I suspect being able to push
| back against the seat helps too, though.
| acomjean wrote:
| I've seen a few of them in the city. The seem great, but
| I wonder how well they steer. They're low to the ground
| and seem less visible (I've seen them with flags). On a
| bike your center of gravity isn't much higher than
| walking, and you can put your feet out quickly and
| essentially be in a standing position .
| shagie wrote:
| They steer well enough for bike trails. Longer (e.g.
| tandem) ones may have some challenges with tighter turns
| (need to do a 90deg adjustment at a light).
|
| Flags are common for recumbent for visibility.
|
| The lower center of gravity and the "it's real hard to
| fall off" can make it useful for people that have
| difficulty with balance. The back seat of a tandem is
| suitable for someone with needs for additional assistance
| ( https://www.terratrike.com/product-
| category/accessories/assi... ) - my mother would go
| tandem with one of her friends who was legally blind and
| needed to use a walker.
| samstave wrote:
| I bike A LOT -- >1,000 a month on a 29" full suspension
| e-bike (Orbea Rise)
|
| But I have been biking daily for morethan a decade, and
| was a daily bike commuter in the bay area for ~15
| years....
|
| I see many recumbent bike a day when on the trail. At
| least >5 a day.
|
| My house backs up to the American River trail, I
| literally leave my house and get directly onto the trail
| in less than 2 mintues.
|
| Recumbents are all over the ART in the Sacramento Area.
|
| One thing I have noticed though, and this is just a
| statistical observation on my part biking that trail
| regularly for ~2 years...
|
| The average Recumbentist is a White Male, Typically with
| a beard >50 years old, 30% are overweigth, 30% are
| average build, 30% look semi/more-fit, 10% are female.
|
| They look fun though. I'd love a long distance camping
| -e-bike version of one with a trailer and a detachable,
| light, curved windscreen that can be put on the top of
| the trailer when one wants.
| shagie wrote:
| > They look fun though. I'd love a long distance camping
| -e-bike version of one with a trailer and a detachable,
| light, curved windscreen that can be put on the top of
| the trailer when one wants.
|
| https://bikeportland.org/2009/11/10/portlands-terracycle-
| unl...
|
| That company appears to be https://t-cycle.com
| bsder wrote:
| > The average Recumbentist is a White Male, Typically
| with a beard >50 years old, 30% are overweigth, 30% are
| average build, 30% look semi/more-fit, 10% are female.
|
| Recumbents also used to be far more expensive than
| standard bicycles (although now there's a lot of
| expensive standard bicycles) so an older demographic
| isn't surprising.
|
| Recumbents are also lower in height and a lot easier on
| people's joints so are particularly good for people who
| have medical issues or mobility impairments. So, again,
| your demographics aren't surprising.
| fnfjfk wrote:
| In terms of efficiency of bicycles alone, aero frames, deep
| wheels, carbon fiber.
|
| Clipless is also an incredibly significant change, but not as
| much of efficiency as the others.
| amluto wrote:
| Carbon fiber?
|
| As I understand it, reducing unsprung weight (which is not
| very much for a bicycle with no suspension beyond the
| tires) can have an outsized effect, but actually reducing
| weight mostly matters for ascending. For non-competitive
| cycling, other factors seem like they should be much more
| significant.
|
| A big one, which is banned in most competitive formats, is
| a fairing. This is much more effective than having a human
| hunker down and try to be aerodynamic. Even for an upright
| cargo bike (which is generally extremely heavy), a fairing
| in front can make a dramatic difference on level ground
| with no wind.
| simlevesque wrote:
| The most important is carbon wheels. Lowering the weight
| of the wheels makes it easier to turn them, especially
| uphill.
| scott_w wrote:
| It's only a slight improvement when accelerating. At
| steady state, the wheel weight is balanced out (half
| moves backwards, half moves forwards).
|
| GCN have done some non-scientific experiments on their
| YouTube channel on this.
|
| The biggest benefit to carbon wheels is you can make them
| deeper for less weight penalty (vs aluminium) which gives
| you a significant aero benefit.
| adgjlsfhk1 wrote:
| Carbon fiber isn't better because of strength, but
| because it's a lot easier to keep somewhat light while
| making aerodynamic shapes.
| r00fus wrote:
| Recumbents are noticeably more efficient than uprights. In
| fact any tech or method that's been banned by UCI should
| make bikes even more efficient.
| kqr wrote:
| I read somewhere (lost to the fickle beasts of memory and
| time, of course) that rowing and the like is not particularly
| effective, precisely because it requires big, slow movements
| against resistance, which the human body is not that
| efficient at[1]. What we are efficient at is quick, light,
| repetitive movements - like pedaling with the proper gear
| selected. This is why Ivan Illich phrased it as the bicycle
| being "the perfect transducer to match man's metabolic energy
| to the impedance of locomotion".
|
| [1]: This is also why rowing and weightlifting are such a
| good type of exercise to get stronger, and why bicycling
| requires that you put in a lot of hours to get stronger from
| it.
| playingalong wrote:
| The idea is older:
|
| https://en.wikipedia.org/wiki/Human-powered_aircraft
| tomcar288 wrote:
| And, in the very very long term 200yrs+, it's one of the few
| truely sustainable forms of transportation.
| twawaaay wrote:
| I think it is closer to 9-10 times (on level asphalt road on a
| "normal" bike) although it heavily depends on some factors like
| speed, type of bike and your proficiency, terrain and type of
| ground.
|
| Riding a bike is most efficient at a certain speed and becomes
| less efficient very quickly as you get faster. So when I mean
| 9-10 times more efficient, I mean a person walking at a
| comfortable speed vs cyclist riding at a comfortable speed (on
| relatively level asphalt road).
| alt227 wrote:
| Only on flat smooth surfaces which are a relatively recent
| invention. Take them on any natural environment and it falls
| very quickly below walking.
| csours wrote:
| The difference between riding on grass and riding on a dirt
| trail is VAST - grass is like 3x worse; but when that dirt
| trail turns into a mud trail, the grass is better.
| bluishgreen wrote:
| Humans made trails by walking for eons before roads were
| envisioned. Maybe for a chariot you need a proper road, but a
| human made trail is just fine for a bicycle.
| sharkweek wrote:
| Not only just fine but often times way more fun!
|
| I rode my mountain bike A TON as a kid, gave it up for the
| more "prestigious" road cycling as an adult, but maybe 2
| years ago bought a mountain bike to ride with my kids.
|
| My goodness it took about five minutes on a local trail to
| feel like that same little kid I was back in the day, the
| feeling of speed, focus, and flow. There's nothing really
| like it for me, as it puts me square in the moment.
| simlevesque wrote:
| Recumbent bicycles in particular.
| matthewmcg wrote:
| It's no coincidence that other human-powered transport
| mechanisms (aircraft, boats, etc.) commonly use pedals for the
| drivetrain. It's a lightweight way to use the body's strongest
| muscles, especially when high power is critical.
|
| See:
|
| https://en.wikipedia.org/wiki/MacCready_Gossamer_Condor
| https://en.wikipedia.org/wiki/MacCready_Gossamer_Albatross
| https://en.wikipedia.org/wiki/MIT_Daedalus
| https://en.wikipedia.org/wiki/AeroVelo_Atlas
| https://en.wikipedia.org/wiki/Hydrocycle
| JoeAltmaier wrote:
| Some (good) e-cars burn ~250Wh per mile.
|
| Humans burn something like 750Kc per hour on a bike, and go 15
| miles
|
| A Wh is ~1Kc (0.8:1 but ok)
|
| That makes bikes, what, 5X more efficient?
| dudzik wrote:
| How did he create the animations?
| aoeusnth1 wrote:
| Custom webgl, I believe. You can check the page source.
| fnord77 wrote:
| the animation is wrong. It shows the wheel of the bike turning
| into the turn as the rider leans over.
|
| In reality, the wheel turns slightly away from the turn. This is
| called "counter steering"
|
| https://en.wikipedia.org/wiki/Countersteering
| matsemann wrote:
| All those mechanics are explained further down. There is a
| whole segment in the visualizations dedicated to steering and
| how you steer the othet way first.
| kazinator wrote:
| Nice demo of countersteering. When you jerk the slider quickly to
| the right, you can see that the right handlebar briefly lunges
| forward (left steer) before the steering recovers to the right.
| It's still noticeable with smaller/slower movements of the
| slider, but not as much.
| photochemsyn wrote:
| This is another awesome post, although it doesn't address the one
| thing about bicycles I can never remember - which of the pedals
| has a reverse-threaded attachment to the pedal crank arm, and
| what's the complete force-based explanation for this necessity?
|
| I'm not even sure if the force responsible for this is friction-
| related, or torque related, or some combination of both (probably
| the latter). The force is transmitted to the chaindrive in an
| off-axis manner, but the pedal itself is further removed from the
| axis, so when you push down on the pedal axis that's ahead of the
| bottom bracket axis - one side will tighten clockwise from the
| pedal's perspective, and the other side will tighten anti-
| clockwise.
|
| Wow I got it right after going through this post! That's a first,
| though I'm still not sure I got all the forces right.
| Brajeshwar wrote:
| You will love the interesting video, "Most People Don't Know How
| Bikes Work" by Veritasium -
| https://www.youtube.com/watch?v=9cNmUNHSBac
| js2 wrote:
| Worth watching but for folks who want a TL;DW:
|
| https://en.wikipedia.org/wiki/Countersteering
| birdyrooster wrote:
| Veritasium is some low quality trash, next.
| GaryNumanVevo wrote:
| Another instant classic from Bartosz Ciechanowski!
| zerr wrote:
| It might not be intentional, but does anyone think that this
| article might be a well executed act of trolling?
| sixstringtheory wrote:
| If you meant nerd sniping, then yes, absolutely!
| zerr wrote:
| Seems like a right term. I mean, if anything, the _length_ of
| the article rings the bell.
| graypegg wrote:
| This is such a well made explanation! Tons to learn from this.
| Good job!
| lbussell wrote:
| This is the greatest explanation of two-wheeled vehicle dynamics
| I've ever seen. Anyone who rides a bicycle or motorcycle should
| read this whole thing!
| skeltoac wrote:
| Wonderful work! While I was reading, the HN points went up 500%
| and my battery fell by 50%.
| thunderbong wrote:
| All the posts on ciechanow.ski are mind-blowing. The graphics,
| the gradual process of explaining from simple fundamental
| concepts to the complete picture.
|
| How I wish our schools would teach like this.
| davidw wrote:
| Bicycles are truly beautiful machines. They are the most energy
| efficient form of transportation. You can travel pretty long
| distances with not that many calories.
| dheera wrote:
| > They are the most energy efficient form of transportation.
|
| If the cyclist is vegan or even an average diet, yes. If the
| cyclist is paleo, a Prius with 2-person occupancy may actually
| be more carbon-efficient:
|
| https://keith.seas.harvard.edu/blog/climate-impacts-biking-v...
| loeg wrote:
| This is definitely the kind of generic tangent / screed I
| believe to be discouraged here.
| scott_w wrote:
| Not even close to true. I can ride 60-70 miles on reasonably
| hilly terrain on about 2000kcal. There's no car that can come
| close to that. And that's assuming drivers don't eat (the
| McDonald's wrappers I see by the side of the road proves that
| they do).
| prmoustache wrote:
| At equal diet, the bicycle always win. You don't eat
| significantly more meat because you are using a bicycle to
| move vs a total couch potato that would use a Prius and eat
| the same.
| dheera wrote:
| I disagree with this. On days I cycle 100km+ in a day I do
| eat vastly more than if I drive 100km and don't exercise.
|
| The energy does have to come from somewhere. If you're only
| cycling 5km in a day the reason you don't notice the
| difference in food quantity is because the amount of energy
| used for that small amount of cycling does not really
| exceed the amount of energy your body uses in a day for
| everything else. When you're cycling 100km, it's a
| different story.
|
| It's an interesting question, and in fact the conversion of
| food to mechanical energy isn't actually very carbon-
| efficient compared to electricity generation or even
| gasoline.
|
| Cars are actually very efficient at what they do, it's just
| that what they do (hauling around a 1000kg metal box) is an
| inefficient way to transport a human, and that's where the
| inefficiency comes from.
|
| If you fill up a large car with full occupancy and go on a
| long road trip, I'd venture to say it's carbon-wise likely
| to be more efficient than all of the occupants cycling,
| regardless of diet.
| scott_w wrote:
| You can disagree all you want. You're still wrong. 100km
| on a bike is 2000kcal. Back of the envelope maths on a
| 65mpg car puts it at 35,000kcal.
| prmoustache wrote:
| Eating more != eating significantly more meat.
|
| I used to be an elite racing cyclist, I know what it is
| to need fuel in a 200km bike race
|
| Besides, riding at conversational slower pace only need a
| fraction of that energy. When I was commuting 75km a day
| myy food intake may be at worst marginally higher than a
| day off.
| PaulDavisThe1st wrote:
| This is completely false. See the numbers in the post
| that for me, right now, is directly below yours:
| https://news.ycombinator.com/item?id=35345400
| hanoz wrote:
| The numbers you link to completely fail to take into
| account the carbon footprint of producing energy in the
| form of food vs in the form of petrol.
| [deleted]
| rmvt wrote:
| if anything this is an argument against the paleo diet and
| nothing else...
| dheera wrote:
| Correct, I wasn't trying to make a statement about specific
| diets, just that diet does make a huge difference in
| evaluating the carbon efficiency of cycling.
| ntonozzi wrote:
| Perhaps more carbon efficient, but 15x less energy efficient:
|
| > Biking takes around 25 kcal/km [iii] above basal
| metabolism, which is equivalent to .11 MJ/km. A typical car
| in the US gets 25 mpg, or 9.5L/100 km, which is equivalent to
| 3.3 MJ/km. The Toyota Prius takes only 5 L/100km, or 1.7
| MJ/km. So a typical car takes 30x more energy per kilometer
| than biking, and a Prius takes 15x more. This is what we
| expect given how much heavier cars are than bikes.
| alt227 wrote:
| >They are the most energy efficient form of transportation.
|
| ...On flat smooth surfaces. On any natural environment or
| terrain they are nowhere near as efficient as walking.
| multjoy wrote:
| The rest of the world disagrees with that assertion.
|
| https://worldbicyclerelief.org
| PaulDavisThe1st wrote:
| Not _any_ natural environment or terrain.
|
| Modern fat bikes will be more efficient than walking in the
| scrub desert where I live, in grasslands, in not too dense
| woodlands, on any kind of open dirt/sand.
| davidw wrote:
| I've done 100 mile MTB races, and while it's not as
| efficient as riding a flat smooth road on a road bike, it's
| probably still more efficient than walking.
|
| Obviously at some point there's a line, where you can't
| ride a bike, but for _most_ roads and trails, the bike is
| going to win.
| jagrsw wrote:
| Hmm.. the acceleration part.
|
| E=(mv^2)/2 - so we put more energy accelerating the bike from
| 10-20m/s than 0-10m/s, no?
|
| Yet a=F/m - which suggests the acceleration is proportional to
| force, which would suggest that applying force F for time t
| should speed you up 0-10m/s the same way as 10-20m/s?
|
| I suspect the force applied to the pedals is not the force which
| is acting on the bike (counter-force of the ground-bike system)
| and this second force is somehow relatable to the current speed
| of the bike, no?
| topaz0 wrote:
| Common mistake: you are confusing energy and momentum, or power
| (rate of energy/work) and force (rate of momentum change). In
| fact, power at constant force is F.v (force time velocity),
| which solves your question.
| aoeusnth1 wrote:
| If you don't shift gears, then your pedals increase in speed as
| your bike accelerates. So your power consumption goes up with
| speed even though force is constant.
| wiredfool wrote:
| Work (change in energy) is F*d, so the force you're applying to
| go from 10->20m/s happens over a larger distance if it's the
| same force.
| NGC404 wrote:
| Somewhat related:
|
| How many neurons does it take to ride a bycicle?
|
| https://paradise.caltech.edu/~cook/papers/TwoNeurons.pdf
| ertucetin wrote:
| I saw the link to this article on Twitter and came here to
| double-check that it is indeed in the top 5
| [deleted]
| mariopt wrote:
| Super intuitive learning physics this way
| margalabargala wrote:
| > The further away that line is from the center of mass, the
| easier it is for the force to rotate the object. In the following
| demonstration, you can apply two forces of the same magnitude to
| two identical boxes. The only difference is the distance to the
| center of mass at which these forces act:
|
| > When the distance between the force-line and the center of mass
| is large, the box spins faster as well. That distance doesn't
| change the acceleration of the box to the right and both boxes
| move with the same linear speed. However, that distance affects
| the angular acceleration of a box - the longer that arm, the
| faster the box spins.
|
| This does not make sense to me. If the two forces are truly of
| equal magnitude, then shouldn't the one that is in-line with the
| center of mass accelerate it faster, since 100% of the force is
| being converted to linear momentum, while the off-center force is
| being split between increasing linear momentum and rotational
| momentum?
|
| This would appear to violate the conservation of energy.
| AnimalMuppet wrote:
| > This does not make sense to me. If the two forces are truly
| of equal magnitude, then shouldn't the one that is in-line with
| the center of mass accelerate it faster, since 100% of the
| force is being converted to linear momentum, while the off-
| center force is being split between increasing linear momentum
| and rotational momentum?
|
| Forces don't "split" that way. 100% of the force goes into
| creating linear acceleration, _and_ 100% of the force goes into
| creating torque.
|
| > This would appear to violate the conservation of energy.
|
| It's not. The off-center force does more work, putting more
| energy into rotation.
| amluto wrote:
| Lots to unpack here.
|
| First, there is no splitting between linear momentum and
| angular momentum per se. They have different units, you can't
| add them, and it makes no sense to say "this is 30% linear
| momentum and 70% angular momentum". But you _can_ calculate how
| much energy is stored in linear motion and how much is stored
| in angular motion, and (at least at non-relativistic speeds),
| you can indeed add them. So you are on to something here.
|
| But Newton's Laws don't lie. If you apply a force F, then
| a=m/F, and the fact that the object is spinning doesn't change
| the acceleration. Yet applying the force off-center does indeed
| seem to add more energy to the object: you're accelerating it
| just as much as if you applied the force on-center and you're
| also spinning it.
|
| So how do you resolve this? A piece of general advice in
| physics (and math, and many other fields) is to state your
| assumptions and your questions precisely and unambiguously. The
| question is: if you apply an equal force to two objects of
| equal mass, and there are no other external forces involved,
| how can one accelerate faster? But just because the forces are
| equal doesn't mean that the work (energy applied) is the same.
| In fact:
|
| W (work) = F (force) * d (distance)
|
| Divide by a small unit of time:
|
| P (power, which is work per unit time) = F * v (velocity, which
| is distance per unit time)
|
| And that's the velocity _of the point that receives the force_.
| And if you look at the animation, you will see that the off-
| center force on the rotating box is applied to a (variable)
| spot on the box that is moving to the right. So the power
| needed to apply the force is larger, and more work is done.
|
| (In fact, the excess velocity is or, so the excess power is For
| = ot (angular velocity times torque), which is exactly the
| power needed to produce angular acceleration. So energy is
| conserved and all is well.)
| margalabargala wrote:
| This makes sense, thank you.
|
| I think in my head I was mixing up "force" and "power"; it's
| clear that with two cubes travelling linearly at the same
| velocity, the one that's also rapidly spinning has more
| energy.
|
| That it can take varying amounts of energy to apply the same
| amount of force to the same object was the missing piece for
| me, since I was thinking of force as power.
| amluto wrote:
| It's fairly easy to demonstrate this if you have a friend
| with a bicycle. Have someone on a bike stay still and hold
| the brakes, and press firmly on their back. It's easy. Then
| have them bike at a slow jogging pace, run along with them,
| and try to apply the same force on their back. It will be
| hard work.
| asah wrote:
| electric bikes have quietly revolutionized nyc delivery, with
| food deliveries now going halfway across manhattan and between
| boroughs, no big deal.
| thallavajhula wrote:
| I saw the domain name "ciechanow.ski" and immediately upvoted it
| even before I opened it. The quality of posts by Bartosz is just
| next level.
| rom1v wrote:
| Same. The blog is just incredible.
| captainmisery wrote:
| Same here. What an amazing content he makes.
| ftxbro wrote:
| Also see the work of Jason Moore (referenced in that blog) for
| whom it seems modeling bicycle dynamics in open source scientific
| python has been a huge passion for him for more than ten years. I
| remember in the scientific python development in those days there
| were these guys from like the hubble optics correction division
| and like the asml metrology department and then this one weird
| bicycle guy lol.
|
| https://moorepants.github.io/dissertation/
|
| https://github.com/moorepants
| matsemann wrote:
| I wrote my master thesis on optimizing bicycle wheels / spokes. I
| actually see I'm cited in the phd he cites, quite a fun surprise!
|
| This is a great article. It showcases lots of the "simple, but
| surprisingly advanced" things surrounding bicycles. Which was
| what got me hooked in the first place. The visualization of how
| you have to turn right to go left is excellent. I've mentioned
| that fact multiple times here on HN, it's not commonly known, you
| just "do it" when you bike! And it explains why you sometimes can
| feel the curb "sucking" you towards it when you try to avoid it:
| you unconsciously avoid turning the wheel towards it, but that
| actually makes it so that you're unable to actually steer away
| from it!
| azibi wrote:
| Also worth mentioning bicycle related is the lifework of Sheldon
| Brown: https://www.sheldonbrown.com
|
| Not fancy looking, but very interesting.
| scastiel wrote:
| Every post on this blog is so impressive! Love it!
| jjcm wrote:
| Bartosz is the quality bar I aspire to when I write my blog
| posts. I've always added interactivity in mine, but they in no
| way approach the detail and polish that he puts into them.
| davnicwil wrote:
| I've always loved that little fact about having to initially turn
| the handlebars the opposite way to initiate a turn.
|
| It's pretty much impossible to believe without thinking it
| through, and yet everyone naturally intuits it.
|
| It's one of my favourite examples of how the brain can just
| 'feel' forces and make the right adjustments incredibly fast. So
| amazing.
| gtop3 wrote:
| This effect has a big play on motorcycles. Riding a bicycle is
| considered prerequisite knowledge for learning to ride a
| motorcycle, largely because of this counter steering. One thing
| that is more pronounced on a motorcycle is that counter
| steering only occurs while the bike is moving at speed. As in,
| you only counter steer a motorcycle above ~10mph (higher for
| some motorcycles). It's really cool to think about how
| intuitive this switch is, almost everyone picks it up quickly
| and it becomes second nature.
| Gracana wrote:
| > As in, you only counter steer a motorcycle above ~10mph
|
| I don't believe that this is true. Can you explain the
| physics?
| kube-system wrote:
| Go play with the animation in the article after the text
|
| > In this next demonstration, the wheel is spinning around
| the red axis, and you can also apply a torque that rotates
| the wheel around the green axis:
|
| At highway speeds on a motorcycle, this effect is very
| strong.
|
| But at low speeds in a parking lot, any gyroscopic effect
| of the slow wheels is nothing compared to a 250lb+
| motorcycle.
|
| Bicycles work the same way when you're moving very slow.
| poorbutdebtfree wrote:
| The "counter steer isn't real" debate about to start again!
| gowld wrote:
| The debate is whether countersteering is something you
| have to consciously do by turning the steering column
| ("yaw"), or whether it's an automatic effect of
| pushing/leaning down on the side you want to turn toward
| ("roll").
|
| "countersteering isn't real" because "steering isn't
| real", cycles at speed turn by leaning/rolling, not
| steering/yawing.
| helaoban wrote:
| If you need to quickly swerve out of the way of an
| obstacle you push hard on the handle and you will
| immediately initiate a turn (you could just as easily say
| that your are initiating a lean). It's also well
| understood that handle bar input allows you to increase /
| adjust the lean mid-corner. I ride and never knew there
| was a debate about this.
| helaoban wrote:
| Ride a motorcycle for 5 minutes and you'll believe.
|
| EDIT: To answer your question more directly, you are
| steering in one direction to initiate a lean in the
| opposite direction. E.g. if you are attempting to turn
| right, you first steer left which generates force in a
| left-sided contact patch in the front tire, which causes
| the bike to lean right. The bike then assumes a stable
| right lean angle (you have to do some work with your body,
| but the bike naturally wants to do this), and the front
| wheel comes back into alignment, and you are now turning
| right.
|
| A good explanation:
| https://www.youtube.com/watch?v=PgUOOwnZcDU Some more
| detail: https://en.wikipedia.org/wiki/Countersteering
|
| EDIT 2: I misread your point. You are correct, counter-
| steering still applies at low speeds but the "feeling" is
| masked by lack of momentum.
| Gracana wrote:
| I have one. I still countersteer to turn in parking lots.
| helaoban wrote:
| Yeah, but you quickly counteract with direct steering
| after you initiate the turn, so the overriding sensation
| is one of direct steering at low speeds, even through the
| physics is the same. This is what I think most people are
| referring to when they talk about high speed / low speed
| steering.
| closeparen wrote:
| In parking lots. It's a different steering regime at
| lower vs higher speeds.
| loeg wrote:
| Countersteering applies at all speeds, it's just that balance
| plays a bigger role at lower speeds. The wikipedia article on
| countersteering goes into this a little bit.
| LanceH wrote:
| Countersteering is convenient, but not required. A bicycle and
| rider are not a single rigid body. You can simply lean to one
| side and you'll have to steer in that direction to keep your
| bike under you -- no countersteer necessary.
|
| _I am not saying people don 't countersteer_, only that it
| isn't necessary to make a turn.
|
| Also, bicycles aren't motorcycles where the weight ratio
| between rider and vehicle is swapped.
|
| If you don't feel like clamping your handlebars so they only
| turn one direction, try this: coast along a straight line (and
| outdoor basketball court is great). Then pick a direction and
| just lean that way. You can absolutely keep your wheels on the
| line until you turn in the direction you picked, with no
| countersteering necessary.
|
| This "fact" came about with a video of low skill riders who
| can't manipulate a bike very well, or don't know what it is
| they're doing when they do it.
| flavius29663 wrote:
| Veritasium did a video where they stopped him from counter-
| steering and couldn't steer anymore.
| https://www.youtube.com/watch?v=9cNmUNHSBac
|
| He might be wrong, and just didn't know enough, but he is
| usually researching his videos very well and I would be
| surprised for him to be wrong about this.
| [deleted]
| yeknoda wrote:
| yay
| [deleted]
| duckmysick wrote:
| Relevant link that I saw on HN earlier this week: someone asks
| people to sketch bicycles and then renders the sketches.
|
| https://www.gianlucagimini.it/portfolio-item/velocipedia/
|
| > Little I knew this is actually a test that psychologists use to
| demonstrate how our brain sometimes tricks us into thinking we
| know something even though we don't.
|
| > I collected hundreds of drawings, building up a collection that
| I think is very precious. There is an incredible diversity of new
| typologies emerging from these crowd-sourced and technically
| error-driven drawings. A single designer could not invent so many
| new bike designs in 100 lifetimes and this is why I look at this
| collection in such awe.
| sneak wrote:
| > _how our brain sometimes tricks us into thinking we know
| something even though we don't_
|
| The way I try to avoid this is to remind myself that knowing
| the name of something is not knowing about something, only
| about the existence of that something.
|
| There are lots of things I know the names of, but relatively
| few things I actually know _about_.
|
| The classic example is asking people to describe the process
| that causes the phases of the moon. Most (myself included the
| first time) describe an eclipse, which is wrong.
| grog454 wrote:
| > remind myself that knowing the name of something is not
| knowing about something
|
| You and Feynman both: https://youtu.be/px_4TxC2mXU
| MrJohz wrote:
| I was just talking to a friend about moon phases the other
| day, saying that I'd never really understood why it does what
| it does, only that vaguely things rotate around each other
| and this _waves hands_ does things.
|
| He explained it like this which really helped: you can choose
| all sorts of frames of reference when you think about this
| stuff, so choose one where the sun and earth are stationary
| compared to each other, and then only the moon is rotating -
| less stuff to think about!
|
| Now you've got the earth spinning very fast in the middle,
| the sun sitting off to one side, and the moon then goes in a
| slow circle around the earth. If it's on the opposite side of
| the earth to the sun, then it's going to be fully lit up, but
| it's also only going to be visible at night. If it's on the
| same side as the sun, then the side that's facing us is going
| to be dark and difficult to see, but it will be in the sky
| during the day, which is why occasionally the moon is visible
| in daytime, even though we all know the moon comes out at
| night.
|
| I think that idea of changing your perspective - in this
| case, literally, by changing the frame of reference - is
| really helpful when it comes to understanding things that we
| only know about. Like, I've known about the solar system
| since I was a kid, I've seen all of the models, I surely made
| my own as a schoolchild - the knowledge is all there! But for
| understanding, I needed to find a new perspective.
|
| That's probably true of the bike thing as well, thinking
| about it. Knowledge of a bike is easy: it's two wheels,
| handlebars, a seat, and pedals. But understanding how a bike
| is made requires thinking about the frame, and that's just a
| squashed parallelogram with a stick coming out of it. Once
| you visualise that, it becomes really obvious how the rest of
| the bike gets put together, but the frame is necessary for
| understanding. Otherwise, you just put together the things
| you know about and then have to draw awkward lines in between
| to connect them.
| jagthebeetle wrote:
| What a great example! As a recent astronomy enthusiast, I
| found myself doubting this comment initially ("well, eclipses
| ARE related"), and this despite the fact that I have a toy
| tellurion right by my desk.
|
| But hearing a particular phrase in the below video helped
| correct my model. One sanity check is that you can see non-
| full moons during the day (although I definitely would have
| just assumed it was still a matter of angles).
|
| Related video: https://www.youtube.com/watch?v=Jip3BbZBpsM
| tellurion wrote:
| Side comment: This is the first time I've seen my preferred
| username used for its actually meaning. And I've been using
| it for almost 3 decades. Neat. I was going to use
| tellurian, which means an inhabitant of the earth, then saw
| that tellurion was sometimes used as an alternate spelling
| in an old Webster's dictionary I was looking through, and
| preferred it. And yes, I did search through a dictionary to
| find a username.
| eshnil wrote:
| Another great interactive explanation.
|
| I wish physics teachers start using geometric product of vectors,
| instead of the cross product. This allows forces and torques to
| be combined into a single concept "Forque". Really, translations
| are just rotations around infinity and rotations are just
| composition of two reflections. If we allow the algebra to take
| care of rotations, physics becomes a lot simpler.
| samstave wrote:
| Wait until (all) teachers start using AND SHARING really well
| crafted prompts for teaching aides /r/coolguides lesson
| material.
|
| There should be a central repo for all subjects where topics
| can be looked up to find a guide like this one - and the prompt
| is public, with revision edit logs (like wikipedia) such that a
| standard agreed upon response can be adopted by acedmia for
| explaining a particle concept.
|
| Let the acedemics expand upon, tangent from, deep dive into the
| sub components of each topic.
|
| The University.ai
| smoyer wrote:
| > Since our planet is very heavy, the acceleration of the Earth
| and the wall attached to it is effectively non-existent.
|
| If the applied force is anchored to the ground too, if doesn't
| matter how heavy the planet is.
| comment_ran wrote:
| Hey there fellow bikers!
|
| I've been having some trouble adjusting the tension in my spokes
| lately. It seems like no matter how much I try, I just can't seem
| to get it right. Does anyone have any tips or tricks they could
| share with me?
|
| On a related note, I've been wondering about the differences
| between mountain bikes and road bikes. One thing I've noticed is
| that when you take a sharp turn on a mountain bike, you tend to
| move the bike away from your body. But on a road bike, you
| maintain that alignment with your body and the frame. It's
| fascinating how these small differences can have such a big
| impact on the way we ride.
|
| What do you all think? Have you noticed any other differences
| between these two types of bikes? Let's chat and share our
| experiences!
| ActorNightly wrote:
| 1. Go around the wheel and use a tension gauge to make all the
| spokes equivalent in tension. Then go around and fix the
| lateral and radial runout.
|
| 2. Has to do with geometry and thickness of the tires.
|
| To generalize the article even more, the way a bike turns is
| like this: for a given speed and radius through a corner, there
| is a necessary lean angle. That lean angle determines the
| camber thrust of the tires, which is the centripetal force that
| makes the bike turn. However, you also have to make the bike
| yaw, which means the front has to generate a greater sideways
| force than the rear. This is accomplished through adding
| steering angle to the front tire. The longer the bike is, the
| greater the difference that is needed between front and rear
| sideways forces.
|
| Furthermore, the steering angle of the front tire is affected
| by the head angle (90-rake angle), and geometric trail (caster
| effect). The greater the geometric trail is, the more the tire
| wants to resist turning. The greater the speed, the higher this
| effect. Conversely, the slacker the head angle is (lower in
| value, greater rake angle), the more the front tire wants to
| turn into the turn (because the wheel axle lower in height with
| increasing steering angle).
|
| The reason why you generally lean the mountain bikes under you
| are 2 fold. First, the bikes are longer, so naturally you need
| the greater difference, which means you need more force from
| the front. You would exceed the max slip angle of the front
| tire if you stayed upright, especially on looser dirt. So
| instead, you lean the bike more to engage camber thrust.
| Secondly, the tires on mountainbikes are designed with side
| knobs specifically for cornering, so you want to engage those
| knobs.
|
| The opposite problem exists on street motorcycles, where the
| bikes need to be low enough to the ground to not backflip on
| acceleration, which limits the available bike lean angle. So
| instead, riders learn to hang off the bike. This in turn
| requires the front end to be turned more. As a consequence of
| this, bikes understeer or oversteer behavior is greatly depends
| on the front end geometry (rake and trail). The trail forces
| are magnified at the higher speeds, so you need careful tuning
| of things like fork offsets (which control trail), and rake
| angle, both of which are affected by suspension moving up and
| down.
|
| Yet, on supermoto bikes (i.e dirtbikes with street tires,
| popular in europe), you don't have the ground clearance
| problem, so you can actually corner them either like street
| bikes with knee down, or dirt bike style while leaning the bike
| under you.
| cloudripper wrote:
| > One thing I've noticed is that when you take a sharp turn on
| a mountain bike, you tend to move the bike away from your body.
| But on a road bike, you maintain that alignment with your body
| and the frame.
|
| I don't know the answer but will toss out a guess.
|
| I'd speculate one of the biggest differences is how each bike
| is used and its intended design based on that use case.
| Centrifugal forces combined with traction of tire to surface
| will be very different between road bike tires at high speed on
| pavement versus mountain bike tire and low/moderate speeds on
| dirt. Beyond that, a mountain bike is often rode through
| technical terrain that requires dynamic balance by the rider
| (rider strategically shifts weight over bike) - whereas road
| bikes appear to be rode with a more "static" balance between
| rider and bike.
| StayTrue wrote:
| You say you have difficulty adjusting spoke tension but you
| don't say what the problem is. Do you have a spoke tensiometer?
| I consider it manadatory (you don't have to have a fancy
| electronic one although they're a pleasure to use).
| acomjean wrote:
| I've never built or adjusted a wheel. My understanding its not
| for the faint of heart. The late husband of one my CS
| professors (Sheldon Brown) put together a solid bike resource
| on the web...
|
| He has some hints on wheel adjustment (after describing
| building)
|
| https://www.sheldonbrown.com/wheelbuild.html
|
| sometimes local bike shops have wheel building classes.
| BrianHenryIE wrote:
| Beautiful article.
|
| There's a similar neat video, "Most People Don't Know How Bikes
| Work", where they fix the steering so the handlebars can only be
| turned left, and people then aren't able to turn left.
|
| https://www.youtube.com/watch?v=9cNmUNHSBac
| ubj wrote:
| Beautifully illustrated and brilliantly explained.
|
| Derek Muller (Veritasium) on YouTube has a related video diving
| into the mechanics of bicycle riding. It shows what happens if
| you prevent the rider from performing the countersteer before
| leaning into a turn [1].
|
| [1]: https://youtu.be/9cNmUNHSBac
| LanceH wrote:
| Try just leaning before steering. Countersteering is not
| required.
| not_the_fda wrote:
| A great book on the science of bicycles is "Bicycling Science"
| from MIT press. https://www.amazon.com/Bicycling-Science-Press-
| Gordon-Wilson...
| bmelton wrote:
| A much worse book on the science of bicycles is "The Third
| Policeman" from Flann O'Brien.
|
| Some of its wisdom: "The gross and net result
| of it is that people who spent most of their natural lives
| riding iron bicycles over the rocky roadsteads of this parish
| get their personalities mixed up with the personalities of
| their bicycle as a result of the interchanging of the atoms of
| each of them and you would be surprised at the number of people
| in these parts who are nearly half people and half
| bicycles...when a man lets things go so far that he is more
| than half a bicycle, you will not see him so much because he
| spends a lot of his time leaning with one elbow on walls or
| standing propped by one foot at kerbstones."
| kitkat_new wrote:
| Link to the book directly from MIT Press:
| https://mitpress.mit.edu/9780262538404/bicycling-science/
| umvi wrote:
| ciechanow.ski pages are usually super performant for me, but this
| one is super laggy, especially widgets with the bicycle man/mesh.
| Anyone else experiencing this?
| nfriedly wrote:
| I'm using Firefox on a mid-range Android phone and it seems to
| behave fine. Maybe reboot your computer and see if the site is
| less laggy?
| gowld wrote:
| Great articles, no ads, except this one:
|
| Voluntary contribution of $3 or more per article, via Patreon:
| https://www.patreon.com/ciechanowski
|
| (Not sure what "per article" means though. How to donate for past
| articles? Will I get billed whenever a new article drops?)
| wintogreen74 wrote:
| >> Once mastered, the simple action of pedaling to move forward
| and turning the handlebars to steer makes bike riding an
| effortless activity.
|
| Except you don't really turn the handlebars to steer, movement is
| far more than just pedaling and it's never an effortless activity
| if done right. Everything else in this sentence is correct though
| ;)
| naillo wrote:
| Awesome stuff as always. Don't forget to support his patreon:
| https://www.patreon.com/ciechanowski
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