Myths in cycling: wider tires are slower

Narrow tyres tubeless is a no-go as the high-psi required to get the tyre seated and shaped can cause blowouts, especially if you get impact such as a pothole.

Going for wider tyres means you naturally can go lower PSI, but if you drop PSI with tubes you risk pinch-flats ('snakebites'), where striking a hard edge causes both edges of the tyre to puncture (like X___X on the cross section, rather than \__x_/ of a normal puncture). If you go wide, you can then drop the pressure more as you don't have a tube to pinch. This gives you the great comfort, the pliability to absorb road imperfection (which improves speed), and less likelihood of puncture.

As an approximate pressure guide:

    # weight in kg. front load probably 0.45 (45%). tyre width in mm
    weight_front = weight * front_wheel_load
    weight_rear = weight * (1 - front_wheel_load)

    psi_front = (338.14 * weight_front / tyre_width ** 1.5785) - 7.1685
    psi_rear = (338.14 * weight_rear / tyre_width ** 1.5785) - 7.1685

This should ballpark you 15% tyre deflection under load, which was a guide from an old bike magazine on a balance of rolling resistance and comfort.

> 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 area.

And given equal force on the tires, wouldn't the same force deform a smaller contact area more, not less? What am I misunderstanding?

> Laboratory tests on steel drums eliminate the rider and thus the suspension losses. If you look at hysteretic losses alone, narrow tires run at higher pressures and thus flex less, meaning they absorb less energy.

> We tested on real roads, with a rider on the bike, and found that the increased vibrations of the narrower tires caused energy losses that canceled out the gains from the reduced flex. These suspension losses are mostly absorbed in the rider’s body.

How do hysteretic losses apply here?

And, why does the increased vibration cause energy losses (which I take to mean reduced efficiency of energy used for movement)? If the energy is absorbed by the tire or is transferred via other bicycle components to the rider, what's the difference in energy loss/efficiency?

If they’re causing you problems, consider replacing them. Otherwise I’d just wait until you get a flat — no point in spending money on something which isn’t a problem. You’re commuting so you’re reliably putting on mileage without [presumably] getting in to dodgy situations or trying to shave every second or gram off.

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.

There's been studies from Bath University, but

https://gearmashers.com/clipless-pedals-vs-flat-pedals-faste...

Here are 2 dudes that did a trial, they produced more watts going up hill in flats, sprints were a big difference though. These were people used to being clipped in, and not using flats.

Where's the studies to the contrary? Nothing I've seen has been more than marginal at best.