4 ms·

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

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 mileage, have shown this. Smaller contact patches (a condition created with over-inflated tires) result in higher gas mileage, whereas larger contact patches (under-inflated tires) lower gas mileage. I didn't see this addressed directly, that I saw.

marwatk 5y ago
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.
- bri3d 5y ago
  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.
  - wiredfool 5y ago
    So, part of the point of the Rene Hearse tires is that they’re as supple as they can possibly make them. They are producing essentially the same best tire that they can in a huge range of sizes. (Well, at least until they started doing endurance casing and knobbies, so now it’s more like 4 of the best tires they can, aimed at slightly different target users/races)
- efraim 5y ago
  Yes, with pneumatic tires the contact patch area is the load force divided by the pressure.
bserge 5y ago
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.
- PragmaticPulp 5y ago
  If you’re going a short distance: No, it doesn’t matter. For a longer ride or a trail ride, the loss from the tires adds up. One extra MPH means a lot when you’re doing a multiple hour ride at an average of 10-15MPH. Tire pressure influences rolling resistance significantly on larger tires. I’ll some times increase pressure on longer rides or for uphill portions. Lower pressures have more traction, so I’ll let air out for the downhills. It doesn’t seem like much, but everything adds up as you push into longer and higher effort rides. Non bikers roll their eyes when we talk about saving small amounts of weight, for example, but it makes a difference over time with less weight to throw around. Again, you won’t notice on short rides around town but when you’re spending tens of hours every week on the bike in increments of 1-3 hour rides, it’s worth optimizing these things.
  - dennisgorelik 5y ago
    > One extra MPH means a lot when you’re doing a multiple hour ride at an average of 10-15MPH. Why spend your effort on optimizing your bike performance by 8% if you can instead simply shorten the distance by 8%?
    - GavinMcG 5y ago
      How exactly do you shorten trails, or race courses?
      - dennisgorelik 5y ago
        > How exactly do you shorten trails You do not go all the way in. Or pick shorter trails. Or allow more time. > race courses? You may do less lapses. Or pick a different (shorter) race.
quietbritishjim 5y ago
In this article, "slower" clearly means "slower [when putting the same amount of power in]". Or, equivalently, "need less power to get the same speed". Of course any tires are the same speed if you adjust the power input to compensate.
efraim 5y ago
The contact patch is only larger if the pressure is lower, and with a wide tire the contact patch is shorter and wider. Because of that there is less deformation of a wider tire along the rolling direction which is what creates rolling resistance.

marwatk 5y ago

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.

bri3d 5y ago
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.
- wiredfool 5y ago
  So, part of the point of the Rene Hearse tires is that they’re as supple as they can possibly make them. They are producing essentially the same best tire that they can in a huge range of sizes. (Well, at least until they started doing endurance casing and knobbies, so now it’s more like 4 of the best tires they can, aimed at slightly different target users/races)
efraim 5y ago
Yes, with pneumatic tires the contact patch area is the load force divided by the pressure.

bserge 5y ago

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.

PragmaticPulp 5y ago
If you’re going a short distance: No, it doesn’t matter. For a longer ride or a trail ride, the loss from the tires adds up. One extra MPH means a lot when you’re doing a multiple hour ride at an average of 10-15MPH. Tire pressure influences rolling resistance significantly on larger tires. I’ll some times increase pressure on longer rides or for uphill portions. Lower pressures have more traction, so I’ll let air out for the downhills. It doesn’t seem like much, but everything adds up as you push into longer and higher effort rides. Non bikers roll their eyes when we talk about saving small amounts of weight, for example, but it makes a difference over time with less weight to throw around. Again, you won’t notice on short rides around town but when you’re spending tens of hours every week on the bike in increments of 1-3 hour rides, it’s worth optimizing these things.
- dennisgorelik 5y ago
  > One extra MPH means a lot when you’re doing a multiple hour ride at an average of 10-15MPH. Why spend your effort on optimizing your bike performance by 8% if you can instead simply shorten the distance by 8%?
  - GavinMcG 5y ago
    How exactly do you shorten trails, or race courses?
    - dennisgorelik 5y ago
      > How exactly do you shorten trails You do not go all the way in. Or pick shorter trails. Or allow more time. > race courses? You may do less lapses. Or pick a different (shorter) race.

quietbritishjim 5y ago

In this article, "slower" clearly means "slower [when putting the same amount of power in]". Or, equivalently, "need less power to get the same speed". Of course any tires are the same speed if you adjust the power input to compensate.

efraim 5y ago

The contact patch is only larger if the pressure is lower, and with a wide tire the contact patch is shorter and wider. Because of that there is less deformation of a wider tire along the rolling direction which is what creates rolling resistance.