higher center of gravity, which is more stable.
you sure about it chief? bigger wheels also have larger rotational inertia
Comment on Why do tires have the width and diameter they do?
OhNoMoreLemmy@lemmy.ml 1 day ago
The answer is rolling resistance.
Tires stick to road which is great for accelerating and breaking, but it makes maintaining your top speed harder. This doesn’t matter if you have a big engine, but it makes a difference if you’re cycling.
For a road bike, you want to minimize the contact area of the tire with the road so you have very narrow tires and inflated a lot so that they don’t deform much under your weight.
The type and width of tires changes depending on what you’re riding on. For off road you have wide knobbly tires that will catch in mud and push you forward. For riding on a beach you have very wide smooth tires for traveling over sand.
rain_enjoyer@sopuli.xyz 1 day ago
OhNoMoreLemmy@lemmy.ml 1 day ago
Yeah, try riding a folding bike with small wheels, you wobble a lot more.
The high inertia has a stabilizing effect.
floquant@lemmy.dbzer0.com 1 day ago
A low center of gravity is more stable than a high one.
Gyroscopic effects do exist on bikes but they are not the main source of stability - it’s the fork geometry, which tends to straighten the handlebar
Successful_Try543@feddit.org 1 day ago
the magnitude of the rotational inertia […] is roughly the same or maybe a bit higher on larger wheels that are probably heavier
The rotational moment of inertia increases a lot due to the larger diameter J ~ m r^2. Even if the masses were the same, the relatively heavy tyre and the rim are further away from the wheel hub.
Successful_Try543@feddit.org 1 day ago
It’s slightly different:
As the top speed of a road bike makes air resistance (drag) an important factor, road bikes use narrow tyres, resulting in a smaller silhouette area than a wide tyre (on a rim of the same diametre) would have.
As the rolling resistance increases with the length of the contact area, with the same internal pressure (inflation), i.e. same area of contact, narrow tyres have a higher rolling resistance than wide tyres. Thus, to (over-)compensate and decrease the length of the area of contact the internal pressure of road bike tyres is much larger than of normal, wider tyres.
As a result, narrow tyres of road bikes have smaller drag and due to over-compensation by inflation an even lower rolling resistance than standard bike tyres.