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

Re: Myths in cycling: wider tires are slower

#101

Post by MarkusWandel » Mon, Jun 14, 2021, 9:11 PM UTC

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 seen people ride tires that can't even survive a couple of kilometers of dirt road.

Re: Myths in cycling: wider tires are slower

#102

Post by japanuspus » Mon, Jun 14, 2021, 9:14 PM UTC

A great source of data on bike tires is [0], which has been doing systematic tests on a dedicated test rig for many years and appears to be independent of any tire manufacturer.

After finding this site a few years back, I bought a high-pressure floor pump and Schwalbe Marathon tires for all the commuter bicycles in the family. Haven't seen a flat tire since, even though we have four bikes on the road almost every day.

[0]: https://www.bicyclerollingresistance.com/the-test

Re: Myths in cycling: wider tires are slower

#103

Post by fsckboy » Mon, Jun 14, 2021, 9:15 PM UTC

carl_dr wrote: post #33

at-fates-hands wrote: post #24

Earlier quoted context omitted.

I was a life long flat pedal rider. Started working at a bike shop during college and one of the first things roadies told me was they are indeed much more efficient because you can push AND pull on your pedals - generating a lot more power and making the ability to sustain that power a lot easier.

I think this is a myth - you don’t pull on your pedals to make you more efficient, I think it’s the fact you are not continuously having to adjust your feet as you would on flat pedals. See https://www.bikeradar.com/advice/fitness-and-training/stop-p... for instance.

a better way to say what you might be saying is, "without locking your feet to the pedal, you expend significant energy with lateral muscle movements to keep your feet on the pedals"

Re: Myths in cycling: wider tires are slower

#104

Post by jcarpio » Mon, Jun 14, 2021, 9:17 PM UTC

soperj wrote: post #5

Another one is that clip in pedals make you faster.

An opinion piece on the matter of being clipped in vs street shoes: https://www.rivbike.com/pages/the-shoes-ruse

Re: Myths in cycling: wider tires are slower

#105

Post by bserge » Mon, Jun 14, 2021, 9:18 PM UTC

falcolas wrote: post #91

So, I wouldn't expect them to be slower (except in the most extreme cases with aerodynamics), since you can make anything go fast with enough power. But along that line of thinking, I would expect larger tires to require more energy to keep at speed. A larger tire with a a larger contact patch implies a greater deformation of the tire, which in turn implying greater energy loss. Cars, using a measurement of gas milea…

Does it really matter? Unless 1 extra mile per hour will make or break your commute or you're racing, just go with the most comfortable choice.

I've been planning an E-Bike conversion and it looks like wider tires would be a better choice, as would shock absorbers which everyone says are less efficient.

I'll give up that efficiency in a second if it means my ass and legs aren't sore when I get to my destination.

Re: Myths in cycling: wider tires are slower

#106

Post by carl_dr » Mon, Jun 14, 2021, 9:19 PM UTC

kazinator wrote: post #70

twoWhlsGud wrote: post #63

Earlier quoted context omitted.

This is all anecdotal, but a couple of decades ago I was riding road bikes with standard 622 rims shod with 23 mm tires. In the 2000s I shifted to riding road bikes with 584 rims and 42mm tires because they were frankly just more fun for me (lower pressure = greater comfort and better suspension meant better handling on our rough Northwest roads). The outer diameter was about the same, so I didn’t have to do somethin…

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.

Re: Myths in cycling: wider tires are slower

#107

Post by oliwarner » Mon, Jun 14, 2021, 9:24 PM UTC

japanuspus wrote: post #102

A great source of data on bike tires is [0], which has been doing systematic tests on a dedicated test rig for many years and appears to be independent of any tire manufacturer. After finding this site a few years back, I bought a high-pressure floor pump and Schwalbe Marathon tires for all the commuter bicycles in the family. Haven't seen a flat tire since, even though we have four bikes on the road almost every day…

They're great tyres for commuting but they're so heavy. When you swap back to regular or race tyres your bike weighs half as much.

Again, I'm not saying they're good tyres, but perhaps best if you have a spare wheelset so you can keep a "fun" set for the weekend.

Re: Myths in cycling: wider tires are slower

#108

Post by wolverine876 » Mon, Jun 14, 2021, 9:26 PM UTC

davisoneee wrote: post #78

wolverine876 wrote: post #74

> in theory , wider tires are faster due to their shorter contact patch, which deforms less as they roll What is meant by "contact patch"? If it means 'portion of tire in contact with the ground': Assuming the tires are the same circumference, I'd expect the front-to-back dimension of the contact area to be the same, and being a wider tire, the side-to-side contact dimension to be larger, creating a larger contact ar…

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.

Re: Myths in cycling: wider tires are slower

#109

Post by fsckboy » Mon, Jun 14, 2021, 9:28 PM UTC

soperj wrote: post #90

at-fates-hands wrote: post #24

Earlier quoted context omitted.

I was a life long flat pedal rider. Started working at a bike shop during college and one of the first things roadies told me was they are indeed much more efficient because you can push AND pull on your pedals - generating a lot more power and making the ability to sustain that power a lot easier.

I use clip ins now, have for about 5-6 years. I don't think you actually pull up.

you should actively pull up your leg so the down leg is not working extra to lift it, and the pull up muscles are different muscles so your idle down muscles are still getting a rest.

The pulling up of your leg results in easier pedaling overall, and it is relatively as if you are pulling up on the pedal. Should you actually then pull up? You should go for the most natural sustainable pedal motion for you. When I pedal I "visualize" my feet going in circles, not up and down, it helps me on the "over the top" and "across the bottom" parts of the circle. keeps me sinusoidal!

If you never pull up at all and you are pedaling and feeling tired, try pulling enough to remove the dead weight leg from the equation and you'll feel rejuvenated.

Re: Myths in cycling: wider tires are slower

#110

Post by bri3d » Mon, Jun 14, 2021, 9:29 PM UTC

marwatk wrote: post #98

falcolas wrote: post #91

So, I wouldn't expect them to be slower (except in the most extreme cases with aerodynamics), since you can make anything go fast with enough power. But along that line of thinking, I would expect larger tires to require more energy to keep at speed. A larger tire with a a larger contact patch implies a greater deformation of the tire, which in turn implying greater energy loss. Cars, using a measurement of gas milea…

Wouldn't the size of the contact patch be dictated entirely by tire pressure and not tire size? A 100lb person+bike and 100psi inflation means 1 sq inch of contact regardless of tire dimensions. They're circles on a plane, after all. In ideal conditions they'd only contact at a single point.

No, because the tire has substantial structure and isn't a latex balloon, for lack of a simpler explanation. In the case of automotive tires, the carcass (structure) of the tire governs the contact patch much more than the inflation amount.