How come cyclists rock back & 4th 2 gain speed @ the start of a trip?

Question

I've done this pretty much every time, such as X'ing the street (but probably not when I begin biking such as from home). I've recognised it, but now I'm curious enough 2 ask about it in Yahoo! Answers. Thus I would like 2 no, like, the mechanics & physics of rocking back & forth 2 begin a trip, & does it usually have 2 take place in certain situations such as w8ng 2 cross streets.

Answer 1

They do it for the same reason you do. They are trying to to get their cadence up as fast as they can.

Answer 2

I think you're referring to when someone stands up to pedal and the bike rocks back and forth?

Standing allows more power to go the pedals quickly because the rider is using his body weight as well as leg muscles. When you stand and rock from side to side you are pressing you're weight down on each pedal and gaining momentum. It's probably easier to start out in a lower gear but if you're on a single speed or fixed gear city bike that wouldn't be possible.

Answer 3

Rocking back and forth at the start of the trip? I've never experienced this, or seen anyone else do it. At the start of a trip your legs should be pretty fresh, and the only reason I can think of for rocking back and forth if to try and exert a bit more energy through the legs - I only really do this when I'm *really* tired, spinning up a steep ascent. As you rock back and forth, you're also pulling on the handlebars to help stabilise your upper body and putting slightly more power into your legs.

You might see examples of this in this vid:

http://www.youtube.com/watch?v=AS0hnCbEj...

Other than that, I really can't think what you're on about.