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Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More

bicyclerollingresistance.com

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Re: Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More

#31

Post by arghwhat »

ActorNightly wrote: post #25
pandemic_region wrote: post #22

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.

>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 r…

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.

Re: Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More

#32

Post by wink »

pandemic_region wrote: post #22

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.

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.

Re: Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More

#33

Post by basil-rash »

ActorNightly wrote: post #25
pandemic_region wrote: post #22

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.

>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 r…

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?

Re: Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More

#34

Post by londons_explore »

Neil44 wrote: post #27
tpm wrote: post #24

Earlier quoted context omitted.

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.

Excelent point. Personally I think I would rather run a few PSI less and have confortable ride.

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.

Re: Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More

#36

Post by bluecalm »

ActorNightly wrote: post #25
pandemic_region wrote: post #22

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.

>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 r…

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.

Re: Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More

#37

Post by wink »

bradfa wrote: post #28
ActorNightly wrote: post #25

Earlier quoted context omitted.

>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 r…

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 smoot…

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).

Re: Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More

#38

Post by bluecalm »

arghwhat wrote: post #31
ActorNightly wrote: post #25

Earlier quoted context omitted.

>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 r…

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…

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.

Re: Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More

#39

Post by bluecalm »

simonbarker87 wrote: post #26

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.

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.

Re: Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More

#40

Post by Arnt »

pandemic_region wrote: post #22

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.

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.

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