Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Myths in cycling: wider tires are slower

renehersecycles.com

Post reply on HN
Print view View original

141–150 of 419 posts

Re: Myths in cycling: wider tires are slower

#141

Post by davidgould »

wolverine876 wrote: post #108
davisoneee wrote: post #78

Earlier quoted context omitted.

If you're going OVER imperfections (i.e. high pressure tyres), you lose some energy going 'up'. If you go THROUGH imperfections (lower pressure) you don't lose so much energy going 'up' as the tyre absorbs rather than bounces you.

Thank you, but maybe I'm being dense: Tire hits bump, causing energy B to impact tire. The whole bike and rider go 'up' or just the tire goes 'up'. How is the former causing more energy loss? The amount of energy is B either way. I can see how one is more comfortable, because the tire takes the hit and not me, but I don't grasp the difference in energy.

The human body is not perfectly elastic, as it is made out of meat. When the bike goes up and down, it makes the meat jiggle or flap which dissipates energy in the flesh as heat. So taking the hit at the tire which is much more elastic instead of in the heavily damped rider is more efficient.

Take a look a slow motion video of riders on a rough road, say some Paris-Roubaix footage and you can see this.

Re: Myths in cycling: wider tires are slower

#142

Post by wiredfool »

carl_dr wrote: post #106
kazinator wrote: post #70

Earlier quoted context omitted.

I suspect that 42mm is already into diminishing returns for road cycling.

I am definitely slower - 4.5mph or so - on my 42mm gravel bike on road than I am on my 32mm road bike. But my road bike has slick tyres and the gravel bike’s tyres are more knobbly, and I run the gravel bike’s tyres at much lower pressure. (And there is the difference in geometry of each bike, too.) I’m not even sure you can buy 42mm slick tyres, so a like-for-like comparison is probably very hard.

Rene Hearse sells tires from 26 mm to 55 mm all with the same tread and casings.

That’s part of why they can do this test with some level of accuracy.

Re: Myths in cycling: wider tires are slower

#143

Post by sam_lowry_ »

jiscariot wrote: post #137
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…

My only complaint about the gravel trend is that at the entry (and mid) level they are often using pretty crappy disc brakes when rim brakes would have been a better choice in 90% of cases. When they are hydraulic, they are a dream to use, but with a cable you really lose the brake feel.

Ha! I only figured it out after buying Kona Rove NRB, which is not even an entry-level bike, but it turned out to have disk brakes and extremely fragile paintwork.

It served me well, but I am still somewhat cautious when descending since then.

Re: Myths in cycling: wider tires are slower

#144

Post by wizzwizz4 »

kazinator wrote: post #44
wizzwizz4 wrote: post #37

Earlier quoted context omitted.

> The coefficient of friction is a constant which depends on the materials. This is an approximation. It holds here, but it doesn't hold for (say) figure skates on road.

That is false; you might be thinking of figure skates on ice. Steel on road obeys coefficient of friction. (I promise I will keep that in mind the next time I attach skates to a bicycle frame.)

Steel on road obeys the coefficient of friction… until it starts cutting into the road. Unless you're very light, that's going to happen if you're going an appreciable speed wearing figure skates and then try to stop.

Re: Myths in cycling: wider tires are slower

#145

Post by kazinator »

fsckboy wrote: post #95
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…

You're commenting on a article that says "we started to question many of the things we had accepted as ‘facts’... we’ll look at some of these myths. We’ll explain why we (and everybody else) used to believe them, and how things really work" But you aren't qualifying what you're saying: Are you telling us what everybody used to believe? Are you saying you see through what everybody says even without empirical testing?…

> Are you telling us what everybody used to believe?

No; pretty much everything in my comment is undisputed old hat, so it is kind of tangential.

The main myth is not that any of that is false, but rather than thin tires more than compensate for these effects due to their reduced air drag and weight and so always end up being advantageous anyway.

(And they almost certainly are on a polished indoor velodrome track, where the effect of surface imperfections is next to nonexistent.)

Re: Myths in cycling: wider tires are slower

#146

Post by germinalphrase »

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…

Rumor has it that a very prominent British Tour de France competitor rides a re-badged/stealth gravel bike because he finds it more comfortable.

Re: Myths in cycling: wider tires are slower

#148

Post by idoubtit »

CalChris wrote: post #49
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?

You can't really rely on the Tour de France peloton for guidance. They're pretty conservative and, to a degree, ruled by fashion and sponsors.

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...

Re: Myths in cycling: wider tires are slower

#149

Post by house9-2 »

plorkyeran wrote: post #53
jaypeg25 wrote: post #48

Earlier quoted context omitted.

I bought a Specialized Diverge over a year ago. It was mostly to commute to and from work, but also to have the ability to take gravel paths and trails on the weekends. It's been awesome but friends have suggested I take off the stock tires and add some new ones. Is it really worth it? The tires are already fairly fat already, at least compared to road bike tires.

The Pathfinder tires that come stock on recent Diverges are pretty widely regarded as not just the worst part of the bike, but a sort of bafflingly bad choice because they aren't even cheap. If you're looking to spend some money upgrading your bike, they're a good place to start.

I've got about 500 miles on my Diverge (and the Pathfinders) the tires ride great.

- Good on the road, even cornering is decent which was unexpected with light tread.

- Great on gravel: flat, uphill, downhill, and cornering

- Decent on single track

I think maybe they get a bad rap because they are on the heavy side for the price? When the time comes for new tires not sure if I will get another pair or try out something different.

Re: Myths in cycling: wider tires are slower

#150

Post by bombcar »

taude wrote: post #34
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?

Here's a pretty interesting article discussing Le Tour slowly getting wider and wider tires, compared to a decade ago [1]. Granted their use case is going to be at a very different scale than most rec/serious non-pro riders. But I know that most all my friends and I ride 28s on our road bikes these days compared to 23s a long time ago. More comfort and more forgiving. My current road bike maxes out at 28, but I'd pro…

You also have the theoretical perfect tire vs the actual best for the rider - the more comfortable tire may be better overall as it allows the rider to perform better and for longer.
Post reply on HN