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Gilius 09-16-09 03:00 PM

How does coasting actually work?
I'm trying to understand how I can "coast" on my bycicle. The net isn't being much help because apparently "coasting" is also a kind of shifter/brake develope by Shimano and it's poluting my search results.

On a car I need to take it out of gear or keep the clutchpedal down to coast but on a bike all I have to do is to stop pedaling and the rear wheel keeps spinning conserving the momentum. What's the mechanism behind this? Are there one-way bearings involved or is there something simpler?

envane 09-16-09 03:24 PM

Gilius 09-17-09 01:35 AM

Thanks. All I needed was the right terminology.

DieselDan 09-17-09 08:13 AM

If coasting ever becomes a problem, try a fixed gear bike.

Lord Chaos 09-17-09 08:59 AM

There are various ways to do it. A coaster brake has a clutch with a sleeve around it; the sleeve provides enough drag that when you backpedal, the parts of the clutch get closer and push two shoes out against the hub shell, or compresses a set of discs, half of which are keyed to the hub.

Freewheels on derailler bikes can us pawls, little bits of hard metal hinged at one end and pressed out by springs. The outboard ends go into notches in the freewheel body. Pedal forward, the pawls engage. Coast, the pawls become stationary and click as the notches go past. There are also ramp-and-roller freewheels: turn the inner part, the rollers go out on ramps and engage the driven element.

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