Originally Posted by
deraltekluge
At my LBS yesterday, a young woman pondering a mountain bike purchase first rode a regular bike with 26" wheels, then later took out a 29'er. She came back with the 29'er and was amazed at the difference she felt.
Originally Posted by
Kabloink
I can't explain the science behind it, but its been my experience that a smaller wheel allows faster acceleration, but it's less efficient once normal riding speed is reached if you only consider the time it takes to go a certain distance. My thinking is that the taller wheel allows the bike to travel farther for each rotation of the wheel.
Also, the smaller wheel seems to take less strength to get up to speed, but requires more effort to maintain the same speed as a bike with taller tires.
More effort, or a higher pedaling cadence? Folding bikes come with taller gearing (if they're using a different drivetrain at all) to account for their smaller wheels. That way, the rider can travel at similar speeds to their large-wheeled bikes while using a similar cadence.
I saw a similar effect when I replaced my car tires with lower profile 70s. it took a higher rpm to maintain the same speed in any gear than what the higher profile tires required. The change in tire size affected the gearing ratios.
Unless you're trying to shorten the overall gearing for track use, there's no reason to end up with a smaller tire circumference on a car. Go wider, get a larger wheel, or do both (my car's stock 195/60-15 tires can be replaced with tires & wheels carrying 205/50-16 or 215/40-17 while keeping an identical rolling circumference).