QUOTE(alexloon @ Jul 7 2017, 03:12 PM)
What you think about 1 1/8 tire compare to 1 3/8?
Thin tire roll faster is a myth from the 70's… so outdated…just like what they say soy oil is healthier than palm oil in the 80s and yet today all fast-food restaurant uses palm oil to replace soy oil because FDA say soy oil is dangerous hydrogenated oil while palm oil is healthy semi-saturated fat.yes FDA ban soy oil.
You would most likely to pump your 1-1/8 to 100psi or more to ensure the tire doesn't bottom out and cause snake bite punture. because of narrower tire, the shape of the contact patch will be elongated, high pressure is very bumpy. I pump my 1-3/8 to 75psi, because its around 22% wider and taller, can go with lower pressure without bottoming up, also, the patch is more rounded and bigger air volume (air cushion) hence it is much more comfortable. Yet still roll fast.
There are many forces acting on the tire, the 2 significant one which we can make a difference through tire selection are one the aforementioned friction force and deformation loss
Deformation force
You want supple tire (tire with thin side wall), i.e. less energy lost through tire deformation when conforming to irregular road surfaces not how narrow the tire that makes the tire fast. Eg. My becha tire is stiff and hard, the rolling resistance is high, replace it with a same size supple tire, the rolling resistance improvement is day and night. It just happened that wide tires are always stiffer than narrow one, so the misconception of narrow tire are easier to pedal and faster.
It's the friction patch size that determine how much friction(anti-rolling force). When you have high pressure, your contact patch is smaller, when you lower the tire pressure, your contact patch gets bigger…
So a fatter tire with wider rim , yes, rim width also affect air volume, more volume = more cushion = more comfy. Doesn't always man slower.
That also explains why really fast tires are very soft and therefore wear out a lot faster. And less punture resistance.
*PS supple tires are tire with really thin side wall, so thin it freak me out.
This post has been edited by KenC: Jul 8 2017, 02:41 AM