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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

#331

Post by jacquesm »

sliken wrote: post #300
kazinator wrote: post #39

Narrower tires, necessarily inflated to a high pressure, are actually inefficient on a bumpy surface. A tire's job is to absorb surface defects in the road, and that is not only for comfort, but rolling efficiency. The extreme example of this occurs off-road. Off-road vehicles benefit from wider tires that are inflated to a lower pressure. If you have an off-road vehicle, it behooves you to take some of the air out o…

Heh, well thin tires are lighter, accelerate better, and have less rolling friction. Alas, that's only true on perfect roads. Even normal road texture on asphalt and cement is enough to lose a fair amount of energy causing vibrations (which is after all a cyclic acceleration) in the bike and rider. I've ridden 125 psi racing tires on a racing bike and noticed that I was noticeably faster (on the speedo) when riding a…

> even to the point of numbness

Even to the point of injury, ganglion cysts are a real risk, especially in wrist joints.

Re: Myths in cycling: wider tires are slower

#332

Post by jacquesm »

gregkerzhner wrote: post #226
MarkusWandel wrote: post #101

Cheap tires are slower. Reliable tires are slower. It's obvious from the pictures that the fatties they're testing are special, with paper thin skinwalls. I can totally see that a high performance fattie would be just as good as a high performance narrow tire. It's the inelastic deformation of the tire casing (and inner tube) that eats power. Unfortunately thin-walled high performance tires are also delicate. I've se…

I’ve been commuting on the extra light Rene Herse tires for about a year in the city and haven’t had a flat. They are set up tubeless though. They are a joy to ride and greatly improved the speed, comfort, and handling of the bike. I was hesitant to get them because most of my riding is on city roads with debree, but haven’t regretted them at all.

Which specific tire model are you using?

Re: Myths in cycling: wider tires are slower

#333

Post by laputan_machine »

consp wrote: post #326
jmilloy wrote: post #219

I think folks might be interested to consider some of the other myths and tests in the series, such as: * Titanium is ligther than steel * Fenders slow you down * Stiffer frames are faster * Disc brakes work better than rim brakes * Higher tire pressure is faster * Bigger wheels roll faster https://www.renehersecycles.com/category/myths-in-cycling/ For more nuanced tire testing and results, check out these two more r…

> * Higher tire pressure is faster For semi-professionals sure this is a myth for normal road surfaces, but for every day use by normal people with no knowledge whatsoever putting just over 2 bar in their wheels since that is what their cars use you definitely win efficiency, al lot.

If I used 32psi in my bicycle tyres I'd be getting pinch flats all the time! I run 35x700c marathon plus', which requires a minimum of 65psi [4 bar] (https://www.schwalbe.com/en/tour-reader/marathon-plus)

Maybe for mountain bike tyres that advice works well.

Re: Myths in cycling: wider tires are slower

#334

Post by globular-toast »

dncornholio wrote: post #308

It's not about drag or friction, it's about weight. Wider tires are heavier. Which is a big no no in professional cycling where every milligram counts.

Actually due to the UCI imposing a minimum weight, they have a fair bit of weight to play with. It's possible to make a bike significantly lighter than the minimum, so they could, for example, choose to make the frame super light to compensate for the weight of the tyres.

Re: Myths in cycling: wider tires are slower

#335

Post by petre »

auxym wrote: post #175
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 many ways, modern gravel bikes are a comeback of the "sport touring" road bikes that were popular from roughly the mid 70s to the mid 90s, then became mostly absent from market. Compared with "racing" bikes, they had wider tires, a more relaxed geometry, and various conveniences such as mounting points for fenders and racks. Thus, they were a much better option for the majority of riders who did not participate in…

The annoying thing is that the industry still tweaks those perfectly functional gravel bikes for "performance" cycling adding useless features like an aggresive low stack geometry, 1x only drivetrain compatibility, nonsense suspension. Jan Heine gave us some of the best advice through Bicycle Quaterly, his books and the Rene Herse website.

Re: Myths in cycling: wider tires are slower

#336

Post by pverghese »

JNRowe wrote: post #324
pverghese wrote: post #302

Earlier quoted context omitted.

Not sure what gear Inoes grenadiers is selling to hobbyists.

Pinarello bikes, Shimano groupsets, Fizik saddles, Kask helmets, Castelli kit, Oakley glasses, and all the other things you see surrounding the fat guy at the coffee shop on a Sunday morning ;)

None of them are the products of Ineos.

Re: Myths in cycling: wider tires are slower

#337

Post by saberdancer »

bernulli wrote: post #131
dredmorbius wrote: post #30

Earlier quoted context omitted.

Static friction being constant regardless of contact surface presumes a uniform surface consistency (uniform frictional coefficient). Large (an knobby) tyres are a statistical bet that there will be sufficient friction somewhere on the contact patch. When riding over nonuniform surfaces (dust, loose pebbles, twigs, mud, leaves, and embedded rock), that's a gamble the large and contoured tyre is far more likely to win…

Is the static friction what is going on with wheels? Why do race cars (dragster, F1, etc) have wide, smooth (un-knobby) tires if it's so disadvantageous (no gain, but higher weight and moment of inertia)?

Softer tires give more grip but are less resistant to shearing forces. Having a wider tire helps with that.

Re: Myths in cycling: wider tires are slower

#338

Post by jacquesm »

bernulli wrote: post #131
dredmorbius wrote: post #30

Earlier quoted context omitted.

Static friction being constant regardless of contact surface presumes a uniform surface consistency (uniform frictional coefficient). Large (an knobby) tyres are a statistical bet that there will be sufficient friction somewhere on the contact patch. When riding over nonuniform surfaces (dust, loose pebbles, twigs, mud, leaves, and embedded rock), that's a gamble the large and contoured tyre is far more likely to win…

Is the static friction what is going on with wheels? Why do race cars (dragster, F1, etc) have wide, smooth (un-knobby) tires if it's so disadvantageous (no gain, but higher weight and moment of inertia)?

When you're outputting on the order of 350 kiloWatt per wheel you want to have enough contact area not to spin through, the same goes for taking fast corners, where that width translates into grip.

Re: Myths in cycling: wider tires are slower

#339

Post by petre »

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.

Not much smaller, 46/30 crank instead of 50/34 and maybe 34 or 36 rear cogs instead of 28 or 32.

Re: Myths in cycling: wider tires are slower

#340

Post by globular-toast »

lmm wrote: post #221
idoubtit wrote: post #148

Earlier quoted context omitted.

Cycling teams spend tens of millions each year, with Ineos going over € 50m some time ago. Are they conservative? They benchmark their material in wind tunnels. Sometimes they bend the rules with high-tech material[^1]. There's no way a team competing in Tour de France would choose fashion over performance. [^1]: https://www.theguardian.com/sport/blog/2017/jul/03/vortex-su...

The whole thing is a fashion show with very narrow limits of what the UCI wants people to do. The rules that ban e.g. the famous Lotus bike were explicitly stated as being meant to discourage wind tunnel testing. Fairings and recumbents have been banned for nearly 100 years because they're too much faster than UCI-style bikes.

It's not about fashion, it's about maintaining an enjoyable and popular sport. 4D chess is probably more "interesting" than regular chess, but people play regular chess because it's a good game that people know and understand. They could start allowing funny looking bikes, maybe off-road sections and, heck, why not an army style assault course? But at that point it's just not the Tour de France any more.
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