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Myths in cycling: wider tires are slower

renehersecycles.com

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Re: Myths in cycling: wider tires are slower

#261

Post by kohlerm »

whakim wrote: post #239
haswell wrote: post #181

Earlier quoted context omitted.

> Anecdotally my gravel bike is faster with 28 mm slick tires than with 42 mm sawtooth tires. Out of curiosity, do you know this to be true, or believe this to be true? I ask because the perception of speed with skinnier tires is one of the things the article touches on. I felt similarly when I put GP5000 28mm slicks on the gravel bike, but when I looked at my ride history, I couldn’t really back that feeling of spee…

You're definitely faster with the GP5000s and it's not just an illusion. The GP5000 is an extremely fast tire - some of the lowest rolling resistance out there as measured scientifically [1]. Even the fastest 38mm tires are probably going to cost you minimum 10 watts per tire over the GP5000; perhaps even double that. [1] https://www.bicyclerollingresistance.com/road-bike-reviews/c...

They test AFAIK under ideal smooth road conditions asconfirmed by the picture. On bumpy roads the 10 watts advantage might quickly disappear

Re: Myths in cycling: wider tires are slower

#262

Post by xcambar »

supersrdjan wrote: post #251
wolrah wrote: post #244

Earlier quoted context omitted.

The second most annoying thing to me about cyclists are the number of them who complain about the quality of the road or path while riding what is more or less a race bike. Shockingly, road race vehicles of any variety generally are not built for comfort or ability to handle less than ideal conditions. Stop acting like you think you're in the TdF and get a bike that makes sense for where you ride.

Ah yes I am a cyclist and I approve this message. Reminds me of this saying from an Indian monk: Where would I find enough leather To cover the entire surface of the earth? But with leather soles beneath my feet,It’s as if the whole world has been covered. Just replace leather soles with sufficiently wide rubber tires

Thanks for the very sensible quote.

Re: Myths in cycling: wider tires are slower

#263

Post by ultrarunner »

LAC-Tech wrote: post #170
ultrarunner wrote: post #135

Earlier quoted context omitted.

I would argue that "designed for [off] road mix" is pretty charitable. A 500-pound dirt bike with a comfortable seating position wins the tough-aesthetics competition, but off road performance is meager at best. I built decent off-road skills on a DL1000, but the weight was always such a liability as to make it impracticable. I moved to a smaller and lighter bike and have more fun, but 99% of people I met in Arizona…

Well there's shades of grey between paved tarmac and proper off road. Not a motorcyclists but I assume these adventure/dual sport bikes perform much better over say unsealed roads, and are at least workable on fire roads.

This is exactly right. The contrast that piqued my interest was something like knobby tires on a heavy bike that spent its life on the street. Turns out people value comfort (here, seating position and long suspension travel), but those things only seem to sell with a rugged aesthetic. Balancing these needs is something of a Hard Problem, so it's interesting to watch this play out throughout the industry.

Re: Myths in cycling: wider tires are slower

#264

Post by vishnugupta »

haswell wrote: post #12

This is one of the reasons I love the emergence of the "Gravel" category of bikes. They look and have geometry similar to a road bike, but they have enough clearance for nice fat gravel tires. I ride in Chicago (shitty roads, potholes & construction are everywhere), and love that I can put nice 38mm+ GravelKing Slick tires on the bike, and still have no problem keeping up with most road bikes. I've gotten funny looks…

In this part of the world they are called "hybrid" bikes[1]. Fast and sleek enough for regular city commute and rugged enough for occasional off-road cycling.

[1] https://www.youtube.com/watch?v=SfLwm_SOzaI

Re: Myths in cycling: wider tires are slower

#265

Post by oriolid »

gnopgnip wrote: post #183
TheAlchemist wrote: post #58

Is the data available somewhere ? It doesn’t match my experience at all. I have a road bike and a gravel bike - same quality range (gravel slightly higher). At low speeds, that may be true - the difference is negligible. But at higher speeds / power outputs, the road bike beats the gravel hands down - by a significant margin (big enough to be felt, without a power meter)

https://www.bicyclerollingresistance.com/ compares some different tires.

Jan Heine's whole claim is that these tests are wrong and his method reveals the truth. It's so frustrating that he doesn't test any mainstream tires so we don't even see how the results match.

Re: Myths in cycling: wider tires are slower

#266

Post by egman_ekki »

rorykoehler wrote: post #250
plorkyeran wrote: post #36

Earlier quoted context omitted.

Yeah, when I first got my gravel bike I thought I'd be sacrificing some road performance for better flexibility and comfort, but that didn't happen. The actual result was that my times on smooth segments were unchanged and I've beaten many of my personal bests on rougher roads (and obviously it's much better on dirt). It's not a perfectly fair comparison because I did upgrade to a nicer bike in the process, but my pr…

Don't gravel bikes have much smaller gear ratios? There is no way a strong road cyclist would have the same times on a gravel bike as a road bike purely due to the size of the front chain ring. I run a semi-compact up front on my road bike and I can't go faster than 53kmh on the flat without my cadence getting too high to sustain for longer periods of time.

I don't think the difference is that large, but there is some. I haven't tried myself, but would be interesting to test it against each other.

You can compare gearing ratios on 99spokes, e.g. https://99spokes.com/compare?bikes=scott-speedster-gravel-20...

Re: Myths in cycling: wider tires are slower

#267

Post by oriolid »

salty_biscuits wrote: post #75
mumblemumble wrote: post #64

Earlier quoted context omitted.

"You can push while you pull" never made much sense to me on the road. Because, you're right, those muscles aren't as efficient, so you're just going to have to pay the expenditure back with interest. But, off-road, it can occasionally be useful to give 'er one or two extra firm strokes to help power over a small rise or whatever.

Off road the trade-off for me has always been "how quickly can I bail when things go wrong?". With spiky flats and sticky shoes I don't really have any problems with making enough power.

The answer is "twist your heel outward". It's not really any more complicated than lifting your foot from the pedal. The direction is different, but this is why you practice unclipping for a while before going off road.

Re: Myths in cycling: wider tires are slower

#268

Post by matsemann »

PaulDavisThe1st wrote: post #177
matsemann wrote: post #121

Earlier quoted context omitted.

Lots of the wattage gains in tests are often only noticeable when the speed approaches 40km/h. Wonder about the effect at pro levels, if 32mm is viable there. My longest is 300km with 35km/h avg (185 miles, ~22mph) running 25mm. No problems with comfort. Never tested other wheels on this bike. But I do have a gravel in same price range with wider tires. That I can follow easily in a group, but alone my speed is slowe…

This is a misconception, I think, although your experience seems like enough that I'm surprised you'd make it. The "big" changes that happen as you approach and go beyond 40km/h are due to (aerodynamic) drag coefficient, which has very, very little to do with the width of your tires. The changes that Heine is talking about are not related to drag coefficient at all. Worth noting that Heine himself is a legendary ultr…

> This is a misconception, I think

My comment was more general, as in that lots of truths and myths about bicycling stems from people talking about different speeds. So stuff like "x doesn't matter" some amateurs say, but that x actually starts to matter when the speed increases. Or the opposite, lots of marketing about how product y saves z watts making us amateurs buy it, but then that test was on a already perfect setup at high speeds we're never gonna reach.

But given most data is pointing to wider being better (or, not less effective but more comfortable) I'm wondering why pros aren't running wider.

Re: Myths in cycling: wider tires are slower

#269

Post by rorykoehler »

egman_ekki wrote: post #266
rorykoehler wrote: post #250

Earlier quoted context omitted.

Don't gravel bikes have much smaller gear ratios? There is no way a strong road cyclist would have the same times on a gravel bike as a road bike purely due to the size of the front chain ring. I run a semi-compact up front on my road bike and I can't go faster than 53kmh on the flat without my cadence getting too high to sustain for longer periods of time.

I don't think the difference is that large, but there is some. I haven't tried myself, but would be interesting to test it against each other. You can compare gearing ratios on 99spokes, e.g. https://99spokes.com/compare?bikes=scott-speedster-gravel-20...

I've been road riding with people who switched to gravel bikes and they were suddenly noticeably slower. They also seemed to run out of gas earlier which means they were expending more energy to keep up.

Re: Myths in cycling: wider tires are slower

#270

Post by pharmakom »

rorykoehler wrote: post #250
plorkyeran wrote: post #36

Earlier quoted context omitted.

Yeah, when I first got my gravel bike I thought I'd be sacrificing some road performance for better flexibility and comfort, but that didn't happen. The actual result was that my times on smooth segments were unchanged and I've beaten many of my personal bests on rougher roads (and obviously it's much better on dirt). It's not a perfectly fair comparison because I did upgrade to a nicer bike in the process, but my pr…

Don't gravel bikes have much smaller gear ratios? There is no way a strong road cyclist would have the same times on a gravel bike as a road bike purely due to the size of the front chain ring. I run a semi-compact up front on my road bike and I can't go faster than 53kmh on the flat without my cadence getting too high to sustain for longer periods of time.

You could put a road groupset on most gravel frames.
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