therealtimshady said:
Thanks for the advice guys - what do you mean by rotating weight?
There is a principle of physics which states that when something is moving (or not moving), it will keep doing that until a force acts on it to change its motion (speed or direction).
The same principle applies to things that rotate. They will tend to keep on rotating at same rotational speed and in the same plane until a force acts on it.
It's called "inertia".
Bicycles have overall mass, as well as components that rotate (e.g. wheels), hence both these principles apply to whenever we want to change the speed or direction of a bicycle.
However:
1. the amount of rotational inertia of the wheels (and the few other components that rotate e.g. cranks) is minuscule compared to the overall inertia of the bike + rider (it's at least two orders of magnitude less).
2. Inertia is only a factor when we are seeking to change speed or direction (e.g. accelerate or brake), and of that total inertia - as per 1. above, the difference in rotational inertia of a light wheel v heavier one is tiny.
3. The greatest resistance forces for general steady state cycling are:
- air resistance (which you reduce with more aerodynamic position and equipment)
- gravity when climbing (which is directly proportional to total weight of bike + rider)
- rolling resistance (which is a function of the road surface and tyres)
When it comes to wheels and speed, aero trumps weight on all but the very steepest of climbs.