[HN Gopher] Bicycle Rolling Resistance: Tire Rolling Resistance ...
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Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More
Author : jacksgt
Score : 82 points
Date : 2024-05-15 07:54 UTC (15 hours ago)
(HTM) web link (www.bicyclerollingresistance.com)
(TXT) w3m dump (www.bicyclerollingresistance.com)
| unnervingduck wrote:
| What a coincidence, earlier this week I thought about changing
| the tires on my MTB to better suit my riding style, and I
| wondered if there are sites with extensive tire reviews.
| Titan2189 wrote:
| "Become a Pro Member"
|
| "One-time payment, no auto-renewal"
|
| [5 lines further down]
|
| "From $ 0.79 / month"
| scott_w wrote:
| I'm a member and this is just saying "it costs $.79 / mo" but
| you pay in one payment.
|
| There's no auto-renewal, you get an email telling you your
| membership is expiring and asks you to pay again.
|
| What you've posted implies they're lying and they are
| verifiably not.
| pbhjpbhj wrote:
| >"it costs $.79 / mo" but you pay in one payment
|
| How do you pay a single one-time payment at a per month rate?
| How many months do they charge for the one-time payment?
|
| Usually a 'single one-time payment' would be a payment for
| life. Typically for apps they're <$10 for the lifetime of the
| buyer (or app if that dies first; there are issues around
| this sort of pricing, but people are expecting a minimum of
| several years).
|
| What you appear to be describing would be a pre- payment plan
| at 80C//mo.
| reedf1 wrote:
| Literally 5 seconds of investigation revealed that they
| offer three durations of membership, each a one off payment
| (the per month pricing is just a representative
| amortisation). This is actually so easy to discover, and so
| easy to understand, that I'm guessing you're just
| reflexively enraged.
| pbhjpbhj wrote:
| Continuing membership requires recurring payment not
| "one-time payment".
| rob74 wrote:
| The registration page
| (https://www.bicyclerollingresistance.com/register) should
| answer your questions: basically you can pay for 30 days,
| one year or two years _in advance_ , and the two year
| membership translates to 79 cents per month. But I still
| think they could have phrased it better in the "Become a
| Pro Member" box...
| scott_w wrote:
| I just explained it in my message: you pay once for a year
| and that's it. This is not a lifetime access, it's a one-
| off payment that gives you access for 12 months. If you
| like it, you purchase again.
|
| I really don't understand how this is confusing for you.
| pbhjpbhj wrote:
| >"If you like it, you purchase again."
|
| This is not what I would call a one-time payment. If you
| wish to continue to use the website you pay again. That's
| just not what "one-time" means to me.
|
| It's not confusing, it's just annoying marketing-speak in
| the sense that (paraphrasing) 'a simple one-time payment'
| is what customers like when purchasing something. Whereas
| the offer is not that, the term has been used in any
| case.
|
| What is offered is 'a subscription without auto-renewal'.
|
| If you really wish to understand my thinking I can
| elucidate you at length, but it seems we've spent way too
| long already discussing understanding of a particular
| piece of marketese.
| scott_w wrote:
| I understand your thinking, it's just inconsistent with
| the rest of the world's understanding of the words.
| pestatije wrote:
| so when they say "one-time payment", do they mean "one-time
| payment per year"?, "per decade"?...
| scott_w wrote:
| No, they say "one-time payment" that gives you access for a
| year. If you want a second year, you make another one-time
| payment. There's no recurring payment, it's totally under
| your control.
| pestatije wrote:
| ah i love this...i have to say i havent checked that
| page...one-time payment, to me, means forever...if you
| have one-time payment per year, you must say so
| bluecalm wrote:
| Or maybe that's you who must adjust your understanding of
| reality. One time payment for forever access to something
| that is constantly updated/cost money to run is not a
| reasonable expectations and no one "must" tell you this.
| You must learn it yourself instead.
| amenhotep wrote:
| In a market where the two dominant modes are a) a
| subscription fee that you have to keep paying and b)
| indefinite membership after one payment, many people reading
| "one-time payment" will immediately assume that means (b) and
| bristle when they realise it's actually (a).
|
| They're not lying as such but it's at least accidentally
| misleading. "It's a subscription" should be up front, then go
| into how it's prepay and well behaved.
| rob74 wrote:
| No idea why you get downvoted... on one hand, a site like this
| one needs some revenue in order to keep up their work, I think
| we can all agree on that one. But unclear messaging about how
| much exactly you will be paying is not going to encourage
| anyone to sign up...
| reedf1 wrote:
| Niche website with extremely thorough and exacting analysis,
| that provides most of its data completely for free has a modest
| payment model. I'm shocked, but because of how strikingly
| reasonable it is.
| zython wrote:
| I wish there was a site that ranks tire grip. Only way to know
| right now is to see who is rolling faster through the corners
| than you and word of mouth.
| scott_w wrote:
| BRR explain why it's difficult. Even testing the grip changes
| the grip profile (via wear) but they do their best.
|
| It's even more difficult with off-road tyres, as it's not
| really the rubber compound providing the grip.
| prmoustache wrote:
| Even that is not realistic as in contradiction with 4 wheels
| setup most people on pavement don't nearly reach the limit of
| grip on 2 wheels. The reward/risk ratio is not high enough.
| You'd need a bot for that on a skidpad test.
|
| Also on 2 wheels going fast around corners doesn't only involve
| grip but confidence. This is partly personal/psychological and
| partly based on feedback from the tire that comes on how the
| carcass of the tire deform while you are leaning the bike. It
| could be that a tire with more grip doesn't give you as much
| confidence as a tire with less grip on which you are closing in
| much closer to the limit.
|
| Off the road the grip is so dependent on surface that it is
| even more difficult. There are tire for dry, mud or mixed
| surfaces and what you will encounter on the trail might be
| somewhere in between all of these.
| matsemann wrote:
| I think it's interesting to have observed the changes over the
| years. Before it was about having as thin tires as possible,
| pumped as hard as possible. Then one realized that only gives a
| low rolling resistance on perfectly even surface, something
| softer can absorb more of the little bumps (and also perhaps not
| fatigue the rider as much from a bumpy ride). Then bytul vs latex
| vs tpu tubes. Or go entirely tubeless is in vogue lately, often
| with wider tires and less air in them.
|
| There are other trade offs than rolling resistance. Like puncture
| resistance, grip/cornering ability, aerodynamics, weight etc.
| that also comes into account when choosing a tire setup.
| ActorNightly wrote:
| > something softer can absorb more of the little bumps (and
| also perhaps not fatigue the rider as much from a bumpy ride).
|
| Not quite. You can air down narrower road tires for this. The
| difference is that a wider tire (i.e a tire with more volume)
| is going to be more efficient at lower psi, because of a wider
| contact patch that ends up spreading the load out more and
| deflecting the tread less.
|
| This effect definitely is pronounced for gravel riding when you
| have to run pressures lower than 60 psi, and a wider tire is
| better. However for on road riding, even on rough roads, a
| narrower tire is going to usually be better, because you gain
| the aerodynamic advantage, even if you run at lower psi. If you
| can sustain above 20 mph, running a 28c tire vs a 38c will save
| you 20 watts, which is noticeable.
|
| >Then bytul vs latex vs tpu tubes.
|
| This matters extremely little for most people. Maybe like 4
| watts at most. For racing, when you are optimizing everything,
| its worth it, but generally tubes matter way less then tire
| selection. That being said, there really isn't any reason not
| to run TPU tubes because they are a lot more pliable and
| puncture resistant.
|
| Generally asking bike industry to do actual engineering is an
| impossible task, but for optimal design there is no reason why
| even road bikes should not have suspension that doesn't rely on
| tire compliance. You can do carbon leaf springs with very small
| dampers. The best we get is suspension stems and seatposts,
| which suck because you still have all that unsprung mass of the
| entire bike bouncing around.
| bluecalm wrote:
| I feel the same about suspension but maybe it's just very
| hard to design. It would need to be very light and aero to
| make it worth it for road bikes which are pretty great on
| roads as they are. For gravel there is the Lauf suspension
| thing and the new light/short suspension forks but I am not
| surprised they are not very popular as a suspension fork
| means regular expensive maintenance. Why not just slap 2+
| inch MTB tires on the bike instead?
| ActorNightly wrote:
| Yep, for the front you can use something like lauf, which
| can be made more aerodynamic with smaller travel for road
| application.
|
| For the rear same idea, make the seat stay and chainstay
| meet earlier and mount the axle mounting dropouts on carbon
| leaf springs in the same way.
|
| You can also add a cable tensioning system to both
| suspension, which can be used as a lockout to make the bike
| more efficient.
| latchkey wrote:
| Lauf owner here (with the weirdo front fork). Absolutely
| love it!
| scott_w wrote:
| > a narrower tire is going to usually be better, because you
| gain the aerodynamic advantage
|
| Testing has shown this to not be true. Width is less
| important than overall shape of the tyre/wheel/bicycle
| interface when it comes to aerodynamics.
| ActorNightly wrote:
| Then everyone in the peloton for races like Paris Roubaix
| would be on 38c gravel tires. The reason they run 28c is
| because while it sucks for cobblestone, there sre flatter
| sections where the aero advantage is worth it.
|
| Per 10mm tire width increase, you are getting 10 watts more
| aero drag at 25 mph.
| wiredfool wrote:
| Van der Pol won on 32mm tires this year, vs his normal
| 28mm.
|
| 32 also happens to be the biggest tire that fits in his
| Canyon race bike.
| scott_w wrote:
| Gravel tyres have higher rolling resistance. Also, beyond
| 32mm, you start risking cornering ability on the road as
| there's more tyre to roll over to change direction.
|
| Aero drag is just not that simple. You can't, without
| testing, make the claim you're making. Also, you can't
| make the claim _outside of the exact setup you tested._ A
| different rider, wheels or bike could test faster on 40mm
| because aerodynamic drag is that difficult to predict.
| Neil44 wrote:
| The rolling resistance data is interesting, but it would be nice
| to see some more realistic testing. For example ramping the
| pressure up on a smooth surface gives lower rolling resistance on
| a rolling road. But in the real world super high pressures cause
| the whole bike and your body to shudder and vibrate, which also
| consumes energy. So there is a sweet spot, between heating the
| tyre up too much, and passing too much vibration through.
| tpm wrote:
| The question is whether more realistic testing is really
| needed. At some speed below 30km/h aero drag takes over and at
| higher speeds that's basically the only thing that matters.
| Unless you are riding steep hills in which case total weight is
| the thing that matters.
| Neil44 wrote:
| Excelent point. Personally I think I would rather run a few
| PSI less and have confortable ride.
| londons_explore wrote:
| can't you also get a smoother ride by having slightly
| slacker spokes on wheels?
|
| Then the wheel rim bounces over every rock and pebble, but
| the axle doesn't.
| tpm wrote:
| Or even very slack spokes, like the Berd (UHMWPE) ones,
| but then power transmission is slightly less efficient.
| _Wintermute wrote:
| Not really, spokes work under tension rather than
| compression, you're essentially hanging from the top-most
| spokes on the wheel.
|
| Also if your spokes are too slack, they can move in the
| hub, cause wear, and are likely to snap at the elbow.
| londons_explore wrote:
| okay - slightly stretchier spokes.
| wiredfool wrote:
| No.
|
| Wheels are a prestressed linear superposition of overall
| tension and a compressive load at the bottom. Generally,
| you'll see ~4 spokes at the bottom of the wheel relaxing
| to take the vertical load. (in a properly built wheel)
|
| This is due to rims not being completely rigid, but being
| a somewhat flexible beam. Rims are nowhere near rigid
| enough to do the "hang from the top" thing.
|
| Spokes will break at the elbow, but generally due to
| fatigue, which is made much worse when there are stress
| reversals. Fatigue is when cyclic loads cause small
| imperfections to grow into cracks, and eventually
| failure. If you have stress reversals under rolling loads
| (where the stress goes from tension to compression,
| anywhere in the spoke elbow) you should expect to see
| spike failures in ~1000 miles. A stress reversal doesn't
| necessarily mean that a spoke is slack, because there are
| some interesting stress patterns in the elbow in poorly
| built wheels.
| _Wintermute wrote:
| The compressive load is negligible, that's why you can
| build a wheel entirely out of non-rigid spokes such as
| liteweight wheels or https://berdspokes.com/
| wiredfool wrote:
| No, you can't, because the elasticity of the spoke
| doesn't depend on the tension, only the cross section of
| the spoke. (and count of spokes, and to a lesser extent
| the lacing pattern).
| ano-ther wrote:
| I appreciate sites like this where they make an effort to
| systematically review products rather than just giving a
| superficial impression or repeating PR.
| https://www.notebookcheck.net/ or https://dpreview.com/ are also
| good examples.
|
| They are also a testament to the dazzling amount of options that
| mature industries seem to produce.
|
| > The Schwalbe _Racing Ray_ is optimized for front tire use and
| is a bit less aggressive than the Schwalbe _Rocket Ron,_ [...]
| Schwalbe suggests pairing the _Racing Ray_ with the _Racing
| Ralph_ (read review), which is optimized for use on the rear
| wheel.
|
| > The _Racing Ray_ used to be only available with the _Addix
| SpeedGrip_ compound, which [is] grippier than their _Addix Speed_
| compound. We just noticed Schwalbe also released a _Super Race
| version with the Addix Speed compound_ somewhere in the last few
| years, and we 're not sure about the front wheel claims for that
| version.
| 303uru wrote:
| As a cyclist, this is a situation in which I find this type of
| reviewing close to worthless to be honest. Throwing a tire on a
| metal roller is very far removed from riding unless you're on a
| velodrome or perfectly maintained road. This has led to a lot
| of push-back in the cycling community against this site and its
| findings. Their testing methodology, especially before they
| made recent changes, largely will prefer skinny, highly
| inflated tires. But in the real world, everyone is finding
| fatter, less inflated tires are faster, because in the real
| world compliance (smoothly rolling over every road variation,
| rock or pebble) is faster.
| cogman10 wrote:
| To add to this, unless you are actually competitively cycling
| (you probably aren't) this sort of thing makes pretty much no
| difference for someone that is using cycling for transport.
|
| It's a bit like obsessing over the lightest frame possible.
| Yeah, we can get a 1lb frame made of space materials but at
| the end of the day it's basically something that will reduce
| a cyclist's average speed by like 0.1mph.
|
| For anyone doing anything other than competitive cycling,
| comfort is far more important than anything else and fat
| wheel bikes with steel frames are damn comfortable to ride
| on.
|
| A relatively heavy bike with giant wheels might take your
| average speed down .5 or even 1 mph. You almost certainly
| won't notice it.
| uxp100 wrote:
| I think it's a little different than bike weight, which
| makes very little difference for anything other than
| lifting it onto a rack or taking it up apartment stairs.
| Rolling resistance makes slightly more difference than
| that.
| tim333 wrote:
| Yeah. Between two brands of racing tyre the difference
| may be small but between racing tyres and some mountain
| bike tyres there's a very noticeable difference.
| ciupicri wrote:
| I've switched to Schwalbe Marathon Almotion from some
| knobby Kenda and they made a night and day difference. It
| was a pleasure to ride in the city.
| ActorNightly wrote:
| A super easy way to tell how efficient a tire is going to roll is
| weight. If you are comparing tires for the same
| diameter/width/tread pattern, in most cases, the lighter tire is
| going to roll better.
|
| Tire rolling resistance comes from effectively the rebound
| damping on the tread. As the tire rolls, the tread on the
| backside of the contact patch takes some time to rebound, so the
| tire is effectively always rolling over a bump that is the
| uncompressed tread the front of the contact patch
|
| The lighter the tire, the less sidewall and puncture material
| there is, which means that the rebound damping on the tire is
| going to be less.
| nl wrote:
| This isn't right. The difference in weight of a tire in the
| same class is insignificant (~400g) compared to the bike (~7kg)
| and the rider.
|
| Indeed based on your explanation the stiffness of the tread is
| going to be as much of a cause as anything.
| matsemann wrote:
| There can be some merit to the fact that the weight in a tire
| is rotating mass, though. But then you get into thoughts
| about that the bottom of the tire is technically standing
| still, and the top of the tire is double the speed of your
| travel. And does it then matter?
| ActorNightly wrote:
| Its a very rough rule, and has exceptions, but its generally
| works out.
|
| Compare continental gatorskins in 28c vs continental gp5000
| in 28c. Gatorskins have more casing to prevent puncture, so
| they are heavier, but that casing also takes away from the
| rolling efficiency.
| pandemic_region wrote:
| Unless you're on the ProTour, choose riding comfort over rolling
| resistance.
|
| Also see https://www.renehersecycles.com/12-myths-in-
| cycling-1-wider-... for a related myth-debunking of the impact of
| tire width (which contributes to rolling resistance) on speed.
| ActorNightly wrote:
| >Unless you're on the ProTour
|
| You don't have to be on the Pro Tour to benefit from aero gains
| with narrower tires. Even moderately fit people usually can
| sustain 15 mph on flat, at which point aero gains start to
| matter. Even more for hilly terrain where you can easily pick
| up over 20 mph on descents. The wider tires roll more efficient
| at lower psi (when you have to air down for comfort). But
| roughness of pavement road usually doesn't require less than 60
| psi, and above 60 psi the rolling resistance of wider tires is
| about the same as narrower tires, but watt savings from aero
| can be significant.
|
| I got a gravel bike to replace my old road bike because
| everyone was raving about it, and I absolutely hated riding it.
| Sure, at slow recreational speeds, it was more comfortable, but
| when getting places, it just didn't roll as well down hills,
| making me having to pedal more over extended times to get
| uphill.
|
| Now I ride an aero road bike with TT bars, with 28c tires, and
| even when running them at 60-70 psi for rough pavement, the
| aero gains from the narrower wheels are significant, as I can
| pick up speeds over 30 mph on some descents which carry me way
| further uphill.
| bradfa wrote:
| It depends on what kinds of roads you ride on. If you're
| always riding nice smooth asphalt, then yes, high pressure
| narrow tires are going to be faster pretty much always. But
| if you're riding on really crappy asphalt, chipseal, or on
| dirt or gravel roads, then a wider more supple tire may be
| just as fast but a whole lot more comfortable due to the
| ability to run lower pressures.
|
| The power losses on a perfectly smooth road are aero and
| rolling resistance. But once you get onto bumpy surfaces, now
| you also need to consider the power losses of the bumps on
| the bike AND on the rider because the rider is the one
| supplying the power, even the power which does not transmit
| through the cranks.
|
| Although I do agree with you partially, if you're racing,
| ride what ever makes you fastest. Energy efficiency isn't
| paramount, getting to the finish first is. But if you're not
| racing, then really consider if the tradeoff of comfort is
| worth it.
|
| The BRR website's test protocol uses a fairly smooth metal
| drum for testing. This is good for testing rolling resistance
| but not for testing total system losses over rough roads. So
| although BRR is a great resource, take it with a grain of
| salt.
| wink wrote:
| The real eye-opener for me were that my kinda knobby MTB
| tires apparently have nearly the exact rolling resistance
| as my Schwalbe Marathon Plus on the Gravel Bike. So
| although they're a lot thinner, nothing is gained here at
| all. (If you assume enough pressure in the MTB tires on
| asphalt).
| tleb_ wrote:
| The article from renehersecycles.com does not really agree
| with your comment, and explains why.
| ActorNightly wrote:
| 28 to 32 is negligible aero wise for most people, I don't
| disagree. 30 mph (or slower into the headwind for an air
| speed of 30 mph) will start to matter a little bit though,
| math doesn't lie.
|
| But saying wider tires are better as a blanket statement
| implies that you can run like 45c gravel tires and still
| have the same aero drag, which is by far not the case.
|
| https://www.hambini.com/cycling-aerodynamics-wider-tires-
| and...
| arghwhat wrote:
| On descents you can also pick up a lot of speed by getting a
| heavier bike and supersizing your meals at McDonalds.
|
| Speed on descents isn't really that relevant - you're
| descending, so unless you're racing it's practically effort-
| less. What matters for people biking normally (i.e., not
| recreational road bike racing) is assistance in the 10-15mph
| regime, on flat terrain or climbing.
|
| Large changes in rolling resistance matters here, like going
| from an almost 40W tire to a 20W tire. But aerodynamics have
| a very minimal effect here, and going below 20W tires won't
| really make a meaningful difference in biking effort compared
| to the effect on your butt and wrists.
| bluecalm wrote:
| Going from 20W tire to 10W tires is going to be massive
| even more so for recreational not so fit riders. Such a
| rider may output 120-150W on average. Getting 20W free
| (there are two tires) results in a difference comparable to
| installing a small motor on your bike.
| arghwhat wrote:
| No: A 20W tire is a 20W tire at 18 mph. At 10 mph, it's
| roughly a 10W tire (rolling resistance should be mostly
| linear at these speeds). Going from 20W to 10W tires
| therefore only saves you 10W total at those speeds.
|
| At 120W, you are idle pedalling. You do not really pedal
| lighter, so saving a few watts mean an increase in speed,
| but as both rolling resistance and aerodynamic drag goes
| up with speed the gain becomes small.
|
| At normal climbs - the time where you'd wish pedalling
| was easier - you're either 1. spend in the area of
| 200-300W maintaining the same speed without increasing
| rolling resistance, making rolling resistance a smaller
| part of the load, or 2. drop to a granny gear, going very
| slow to maintain your 120W and thus making the rolling
| resistance negligible with any tire. In either case,
| rolling resistance matters much less in climbs.
| ActorNightly wrote:
| Yes if you bike slowly, wider tires are better. However I
| mentioned that in my post. A lot of people who are into
| biking are in the fitness zone where they are going into
| speeds where aero starts to matter way more. This is
| especially true when you consider wind.
| arghwhat wrote:
| Quoting the article posted in another comment
| (https://www.renehersecycles.com/12-myths-in-
| cycling-1-wider-...)
|
| > The German magazine TOUR built a sophisticated setup
| with a motorized dummy rider and found that a 28 mm-wide
| tire had the same wind resistance as a 25 mm tire when
| the wind was coming from straight ahead. With a
| crosswind, the wider tire was very slightly less
| aerodynamic. Even then, the wider tires required only 5
| watt more - on real roads, the reduced suspension losses
| make up for that.
|
| > To summarize all this research: Narrow tires (<25 mm)
| are slow. Above 25 mm, the width of your tires are won't
| change your speed on smooth pavement (at least up to 54
| mm wide tires). On rough surfaces, wider tires are
| faster. That doesn't mean you can just slap any wide
| tires on your bike and expect it to go fast.
| basil-rash wrote:
| If your primary goal is minimizing work, you can also try an
| electric bike, or driving!
|
| Tongue in cheek, but isn't fitness the point?
| grayrest wrote:
| While it's certainly possible to have a throttle most
| electric bikes require pedaling and therefore some degree
| of exercise. In many cases it gets people riding that would
| not be riding otherwise. For people that are actually
| interested in fitness it's a lot easier to maintain zone 2
| on real roads with electric assist without the impulse to
| push it a bit up the hills. I did far more aggressive rides
| when I had access to my electric road bike than I do on
| other bikes because I knew I had a bail out if I pushed too
| far. Nobody's going to congratulate an e-bike rider on
| their feats of endurance or power but there are lots of
| points between a normal cycling effort and no effort at
| all.
| ActorNightly wrote:
| Same fitness on a more efficient bike = longer distance or
| higher speed.
| bluecalm wrote:
| Gravel bikes are going to transform in coming years as now
| they are neither very comfortable nor fast. It turns out that
| wider MTB tires are both faster (when it comes to rolling
| resistance) and way more comfortable and safer than gravel
| tires even on tarmac, let alone any kind of terrain.
|
| The reason is that soft casing is way more important than
| knobs when it comes to rolling resistance and MTB tires can
| be made soft because all the additional rubber coming with
| width while gravel tires are usually harder and thus slower
| (and less grippy and less comfotable). Notable exception is
| Continental Terra Speed but it's still not as good as Race
| King and way more puncture prone.
|
| The problem with most current gravel frames is that they
| don't fit wide and fast MTB tires so you are stuck with the
| worst of both worlds - slow, not comfortable and still not
| grippy/soft enough to go fast off-road unless it's a very
| well maintained road.
| latchkey wrote:
| I absolutely love my Lauf with their weird suspension front
| fork. Bike is super comfortable to ride. Also has plenty of
| width room for wider tires. I run WTB Nano 40c, which are a
| great mix for road/gravel.
| ActorNightly wrote:
| >It turns out that wider MTB tires are both faster (when it
| comes to rolling resistance) and way more comfortable and
| safer than gravel tires even on tarmac, let alone any kind
| of terrain.
|
| ...except when you are going fast. But I do agree that
| honestly, full on XC MTB are better than any gravel bike
| for mixed terrain. Modern race XC bikes are not only
| lightweight, but have enough suspension travel front and
| rear to tackle super rough trails, which means you don't
| have to rely on tire pressure for compliance (although QC
| on the carbon frames is questionable even from the bigger
| brands).
|
| That being said, when it comes to road, ultimately, aero
| bikes are still king for efficiency if you are least
| moderately fit.
| aayjaychan wrote:
| it's always wild to me hearing what pressure people use.
|
| on my road bike with 28c and inner tubes, 60 psi is what i
| use on _good_ road surface. maybe the roads are just shit
| here, but even 55 psi feel rough. i usually run on around 50
| psi, 40 in winter.
|
| there was a time i lost my track pump and i just pump the
| tyres using a mini pump without a guage. later i discovered i
| was running on something as low as 30 psi.
|
| i have never had a pinch flat. i don't think i'm particularly
| light. full load when doing groceries is probably 85 kg. is
| it just that my pressure juage is woefully inaccurate?
| pmontra wrote:
| 28 mm tires used to be huge tires. Pros didn't ride anything
| wider than 23 mm in the 90s. 25 mm would be for special
| occasions. 21 mm on tracks, sometimes even 19 mm.
|
| I think than Valverde used a 28 mm in a Roubaix and at the
| end of the race said that it was too much and not worth of
| the extra weight and front section.
|
| Every pro is riding on 30 or 32 mm now. Of course the rims
| are totally different and wrap those tires in a way that the
| old metallic rims could not do, hence the aerodynamic gains.
|
| Edit: I've got a gravel bike with 42 mm tires and a 28 mm
| set. I use the 28 mm when going in the hills on asphalt. I'm
| with you on that: it's a day/night difference. On mixed
| mostly flat terrains the 42 mm tires are the best compromise.
| bennyelv wrote:
| Unfortunately you cannot discount the "sponsor effect"
| here. Wheel manufacturers have been pushing wider rims
| because it helps them sell another set of wheels to
| everyone.
|
| In the days of rim brakes a wheel had a finite life (the
| length of time it took to wear down the braking surface).
| Then shimano and the frame builders pushed everyone to disc
| brakes, so the wheels now last for ever. What do you know,
| 2 years later all the wheel manufacturers are claiming
| "wide is better" and flogging everyone new wheels.
|
| I've not seen any clear evidence that they're right, and
| there's lots of intuitive reasons to think that wider tyres
| will be slower (aerodynamics!). I remain sceptical, but
| genuinely hopeful that someone who thinks that wider is
| faster can provide me with some solid evidence...
| mariusor wrote:
| I feel that any marketing strategy that relies on the
| niche of a niche formed of the people that would buy the
| cutting edge cycling gear just because it's presented as
| an improvement over the status quo, would hardly bring
| any benefits to any wheel maker.
|
| I am 100% sure that in this age of "marginal gains", the
| pro tour teams would not go for anything that doesn't
| give them it unless severely hamstrung by sponsorship
| deals. And I doubt that the wheel sponsors don't have
| multiple sizes available.
|
| And I think you're severely overestimating wheel life
| span for modern models, at least due to the fact that
| carbon is more brittle than more pedestrian materials.
| Just look for Pogacar's fall earlier last week in the
| Giro to see how a simple flat tire makes the whole wheel
| a risk.
| 303uru wrote:
| You're kidding yourself if you think Pogacar would run
| 30mm tires at 55 PSI at the detriment of speed to please
| his sponsors. Cyclists are notorious for re-badging stuff
| they don't want to use and being super finicky with their
| gear. You're talking about guys that hardly celebrate a
| win with a $250k purse because they want to make sure
| they stopped their ride right on the finish line on their
| headunit.
| alephxyz wrote:
| > Wheel manufacturers have been pushing wider rims
| because it helps them sell another set of wheels to
| everyone.
|
| I think the push to wider tires and lower pressures on
| road setups is actually because hookless carbon rims are
| much easier to manufacture than clinchers, and hookless
| tires can't handle 80+ psi.
|
| Clincher carbon wheels are basically considered a niche
| product by big manufacturers
| wiredfool wrote:
| I bet if you ran the same tires in 42 and 28, you'd be
| basically at the same speed, at least on smooth roads.
| edmundo wrote:
| >Speeds over 30 mph on some descents
|
| All that aero is probably not working so well for you. Even
| on my mountain bike with grippy and wide tires I get over 40
| mph. On my gravel I can hit over 50 mph, and thats with 45mm
| tires.
| dbrowne wrote:
| I can get close to 50 mph (safely) downhill on my 30 year
| old steel framed 8 speed bike with 20mm tubular tires
| pumped to 120 psi. No problem with riding at 20 mph on the
| flats and I'm close to 60 years of age. My "aero" CF bikes
| with deep carbon rims are minimally faster. Speed is
| irrelevant unless you are racing. Enjoy the ride and stop
| relying on equipment for minimal performance gains.
| ActorNightly wrote:
| Its totally possible to hit over 40 mph on steep hills on
| an MTB, especially if you weigh more. I was more referring
| to slight grades with just pure rolling without pedaling.
|
| Im in Austin so I frequent COTA Bike nights on Tuesdays on
| the track. Coming down the hill from turn 1 with other
| riders is a very good test of aero efficiency, because
| there is a slight uphill after the bend. Couple of my
| friends ride gravel bikes, one of them is heavier than me,
| and its pretty clear that that my bike is more efficient.
| YuukiRey wrote:
| Aero also matters at low speeds since you spend more time on
| the course
| wink wrote:
| If you look at the tires (let's ignore road bikes for now) the
| vast majority is between 15ish and 28ish Watts (I usually look
| at Gravel and MTB tires).
|
| Then look at the methodology:
|
| > The total rolling resistance of an average rider with a total
| bike + rider weight of 85 kg / 188 lbs that averages 28.8 km/h
| / 18 mph will be double the rolling resistance you can find on
| our website. If you're heavier than that or average higher
| speeds, the total rolling resistance will increase roughly
| linearly with the increase in weight or speed.
|
| All I can say is that I am a lot heavier than 85kg with my bike
| and that I am usually riding at 20-25 km/h.
|
| So let's say the lower bound they mention would 2x15 and the
| upper bound 2x25. Let's assume 127kg with luggage, that scales
| linearly to 3x15 - 3x25, but the speed is only 2/3, so we can
| dial it back. My napkin math now says the difference between a
| good pair of tires and a bad one is 30 vs 50.
|
| And I'm still not sure if that translates 1:1 to the assumed
| typical 100 Watts of an average rider..
|
| I found https://www.gribble.org/cycling/power_v_speed.html
| though and if I plug in my numbers, the coefficient of rolling
| resistance is our variable, and
|
| 0.00465 -> Rolling resistance is working against you with 5.79
| (N) of force, or 50.15 watts of power.
|
| 0.00273 -> Rolling resistance is working against you with 3.40
| (N) of force, or 30.01 watts of power.
|
| So the tires make about 2-3 kph, which fits what most people
| have posted when I was researching this.
| Arnt wrote:
| What's riding comfort?
|
| I let both of my kids try things and choose, both choose tires
| with fairly low resistance. One more so than the other, but
| both clearly regarded high pressure as somehow comfortable:
| Apply pressure to pedal, feel bike move. Responsiveness.
| kohlerm wrote:
| Riding is more fun with less resistance, it just "feels
| better". That alone is an argument to choose the correct tire
| (there are trade offs obviously). From my own experience (MTB)
| I can say that the difference in rolling resistance are very
| noticeable.
| wffurr wrote:
| I choose flat resistance over either. Schwalbe Marathons or
| equivalent on all my bikes, but I use my bikes as my primary
| mode of transportation in the city. I really don't want to deal
| with flats when I have to be on time.
|
| Edit: after browsing the site, the Marathons are the lowest
| rolling resistance touring tires too! Double bonus for an
| excellent tire, which I can now recommend without reservations.
| bgribble wrote:
| Marathons have been my tire for about 15 years of city and
| road riding, and I have only flatted once -- direct hit on a
| nail IIRC. I am always amazed at their longevity and
| reliability.
| fenazego wrote:
| I like the Marathons for the same reasons. Only in cold
| weather it's like the rubber of the tyres gets quite a bit
| stiffer (more so than other tyres), and provides less grip,
| just when you need it.
| scott_w wrote:
| BRR is not promoting harder tyres to lower CRR. What it lets
| you do is compare CRR across different tyres at similar
| pressures. Generally, wider tyres with lower pressure gives
| better CRR than narrower tyres at high pressure.
|
| Happily, this is also more comfortable.
| MrSkelter wrote:
| You can have both. Wider tires are faster and more comfortable.
| It's only at the point aero becomes a limiting factor that
| things change. In the real world most of what we "know" about
| tires is a myth (and the linked site isn't doing real world
| testing)
| simonbarker87 wrote:
| Not sure how valid this really is for mountain bike tyres as the
| terrain is so varied.
|
| For example if you run an MTB tyre hard it will bounce around on
| a rocky surface and roll less efficiently than if you run it at
| lower pressure that allows the tyre to deform and bounce around
| less.
|
| Interesting site nonetheless and a useful data point to compare
| tyres in a systematic way.
| bradfa wrote:
| It isn't valid for mountain bike tires, except for when you're
| riding your mountain bike on a smooth road.
|
| The only tests which BRR does which are likely applicable to
| mountain bike tires mounted to mountain bikes ridden on trails
| are the puncture tests, as you're likely to find sharp objects
| even on trails. Maybe the wet grip tests matter, if you often
| encounter wet large rock that you ride on.
| bluecalm wrote:
| It turns out the test is remarkably useful: fast tires on BRR
| are fast tires on various terrains. It turns out that fast
| tires are fast on everything and slow tires are slow on
| everything. It's true you can't say that about pressure (high
| pressure is slightly faster on perfect road but much slower on
| not so perfect one) but when it comes to tire choice it's a
| very good resource.
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