Myths in cycling: wider tires are slower • Hacker News Board

Re: Myths in cycling: wider tires are slower

#251

Post by supersrdjan » Tue, Jun 15, 2021, 5:23 AM UTC

wolrah wrote: post #244

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…

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

Re: Myths in cycling: wider tires are slower

#252

Post by medstrom » Tue, Jun 15, 2021, 5:24 AM UTC

carl_dr wrote: post #15

louthy wrote: post #2

If that were the case, surely Tour de France riders would use wider tyres to gain more grip going around corners, especially in time-trials or stages with sprint finishes. Doesn’t a greater surface area touching the floor means more frictional effects when pushing against the road?

From TFA: “ We tested our tires on smooth pavement at 29.5 km/h (18.3 mph), and found no speed difference between narrow and wide tires.” A professional peloton rides at 28-30mph on the flat and significantly faster towards the end of a flat stage - I bet at higher speeds, for professionals where every percent matters, it does make a difference. Certainly for my level (and I have ridden for an hour at 18mph average)…

"We tested our tires at the same speeds and found no speed difference". You don't say?

Re: Myths in cycling: wider tires are slower

#253

Post by masklinn » Tue, Jun 15, 2021, 5:34 AM UTC

alanbernstein wrote: post #227

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…

These are interesting articles, but in https://www.renehersecycles.com/myth-12-disc-brakes-work-bet... , it just says outright "Many rim brakes for wide tires are too weak to do this quickly, so in the rain, you end up with almost no braking power at all." It's not a myth, it's just conditionally true.

> It's not a myth, it's just conditionally true.

Sounds to me like it’s generally true, and conditionally not: in good condition with thin tires on a metal wheel good rim brakes can be better than disc.

Je general case is thus that you’re better off with disc as default.

Re: Myths in cycling: wider tires are slower

#254

Post by kohlerm » Tue, Jun 15, 2021, 5:48 AM UTC

analog31 wrote: post #216

jmilloy wrote: post #191

Earlier quoted context omitted.

Indeed! In the same series: Myth: disc brakes work better than rim brakes[0]. The rim is the rotor of a bit disc brake rotor that cools better and doesn't add any weight. But the wider tires make disc brakes a necessary choice. [0] https://www.renehersecycles.com/myth-12-disc-brakes-work-bet...

While I don't dispute this, and I have both kinds of bikes, when I talk to "casual" cyclists who have tried disc brakes, they almost unanimously describe the difference as being like night and day. Perhaps the issue is that they are comparing new disc brakes on good bikes, to old crappy neglected rim brakes on cheap bikes. Still, the difference in popularity is unmistakable. Myself, I'm not getting rid of my rim brak…

For pure road bikes rim brakes are ok IMHO only under certain conditions.e.g. no carbon rims and not much dirt and try conditions. These are not the conditions you will find off-road. Also the difference in wet conditions is IMHo still night and day.

Re: Myths in cycling: wider tires are slower

#255

Post by Xylakant » Tue, Jun 15, 2021, 5:52 AM UTC

alanbernstein wrote: post #227

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…

These are interesting articles, but in https://www.renehersecycles.com/myth-12-disc-brakes-work-bet... , it just says outright "Many rim brakes for wide tires are too weak to do this quickly, so in the rain, you end up with almost no braking power at all." It's not a myth, it's just conditionally true.

You should also keep in mind that the articles are slightly dated, so technical improvements may have changed the equation. For example in the comments thread for the disc brake article, people mention that they cannot find disc rotors with sufficient size for tandems. With the rise of cargo and electric bikes, disc brakes with pretty massive stopping power have come to market. Mine can safely stop the bike, me, plus 100kg of extra load for a total of about 250kg [1], the R+M Load Cargo has an S-Pedelec version with a powered top speed of 45km/h. Those brakes will work for any tandem as well.

[1] yes, I tried.

Re: Myths in cycling: wider tires are slower

#256

Post by zrav » Tue, Jun 15, 2021, 5:53 AM UTC

Tangentially the same is true for mountain bikes to a degree, and for a reason not mentioned in the article: Wider tires (run with lower pressure) cope better with uneven or soft terrain. This can easily be verified by riding different tires on grass, sand or deep gravel. On the other hand, on smooth and hard ground wider MTB tires do indeed have higher resistance. This was experimentally documented by the German "Bike" magazine.

Re: Myths in cycling: wider tires are slower

#257

Post by oriolid » Tue, Jun 15, 2021, 5:53 AM UTC

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.

If you want fairings and recumbents, look up IHPVA. They have been arranging competitions where these are allowed for a long time, with very little popularity. I think the main reason is that time trials where the team with most money wins are boring, and UCI has more or less figured out what limitations make the race interesting.

Now compare the situation with mountain biking. UCI didn't adopt it at first either (IIRC the claimed reason was they already have cyclocross that is almost the same thing), but after it was popular enough they didn't really have a choice.

Re: Myths in cycling: wider tires are slower

#258

Post by gorgoiler » Tue, Jun 15, 2021, 5:56 AM UTC

hypnoscripto wrote: post #223

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…

Is that different from a "hybrid" bike?

Gravel bikes are more sporty. They come with drop bars and geometry to complement that riding position, and will weigh much less than an upright hybrid.

You’ll also find gears to accommodate more speeds and inclines, typically a single chainring with an 11 speed lightweight derailleur vs 3 to 9 speed heavyweight (but clean and easy maintenance) hub gears.

Re: Myths in cycling: wider tires are slower

#259

Post by oriolid » Tue, Jun 15, 2021, 5:58 AM UTC

localhost wrote: post #157

mijamo wrote: post #126

Earlier quoted context omitted.

This is actually not really true. Competition bikes have a minimum weight nowadays, and technology is that advanced that it wouldn't be a problem to add some weight here or there because the bike would stay the same weight in total as they have so much margin else to keep in track with the minimum weight. This is why most teams have switched to disk brakes btw, and that they can have all the electronics onboard with…

But there's rolling "sprung" vs. static "unsprung" weight (the examples you listed). You care a lot more about rolling weight as that affects the acceleration characteristics of the wheel - that's really important at the limits.

If you bother to do the math, but simplify things so that all the mass of wheels is at the contact patch, you'll end up that rotating mass has twice the kinetic energy and takes 2x effort to accelerate and decelerate. Now if you check how large fraction of the mass of rider and bike the wheels are and how fast bikes accelerate, it's kind of insignificant.

Re: Myths in cycling: wider tires are slower

#260

Post by amagumori » Tue, Jun 15, 2021, 6:00 AM UTC

ok, so i'm curious how people feel about this, but i believe, for road riding, wider tires actually do make you faster, to a point of diminishing returns around 32c, because of cadence.

when you hit a bump with high PSI / road tires, your wheel bounces, you're momentarily unweighted from the pedals, and that means your cadence is interrupted. anyone who has raced cyclocross knows; there's a LOT of skill involved in applying pedal strokes at just the right times to absorb bumps while also continuing to apply power, and it's way less efficient than just riding clipless on a freshly paved road. every bump "resets" your muscle contraction cycle, and after a bump, you're often not at the right crank position to apply a hard, sharp pedal stroke to try to catch up.

i believe a ton of efficiency is lost through this biomechanical effect on cadence alone, and that's saying nothing of how much energy you lose in the transfer of forward momentum to an upward bounce impulse.