Coaster Brake vs Fixed Gear SKIDZZZZZ
10-13-09, 02:27 PM
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Coaster Brake vs Fixed Gear SKIDZZZZZ
why is it that locking up the rear wheel on a coaster brake is so much easier than locking it up on a fixed gear? on a coaster brake (with similar gearing) i can lock up the wheel with ease, in sandals, seated, sipping my mocha lattechino grande... yet on my fixed gear i gotta either be clipped in and at least stand up, or i gotta put the nuts on the stem. either way it's much more difficult.
i don't know exactly what's going on in a coaster hub, but it's still backpressure on the pedals locking up the rear wheel. what's the difference? what's the coaster hub doing?
i don't know exactly what's going on in a coaster hub, but it's still backpressure on the pedals locking up the rear wheel. what's the difference? what's the coaster hub doing?
10-13-09, 02:34 PM
#2
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The coaster hub translates backpressure on the pedals onto a drum braking mechanism, not directly into the drivetrain like on a fixed gear.
10-13-09, 03:01 PM
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Ya know the caliper / V-brakes some nerds use? And how they can skid a wheel just using their FINGERS?
It's kinda like that.
Friction, and leverage. That's how a coasted brake works better than backpressure on a fixed drivetrain.
It's kinda like that.
Friction, and leverage. That's how a coasted brake works better than backpressure on a fixed drivetrain.
10-13-09, 03:09 PM
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Look up an exploded diagram of a coaster hub if you really want to understand.
Here, I'll even look it up for you.
10-13-09, 04:48 PM
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i'm not trying to be a dick or anything, but you need to take a look at the mechanism. Your ability to coast and line up the cranks to provide stopping power help as well. There are two brake shoes inside the hub of a coaster brake, and when you activate it there is a mechanism that forces the shoes to expand against the hub creating friction and slowing you down.
those brake shoes inthe picture expand against the hub. see how when you back pedal or rotate the brake arm that it pushes those shoes against the cone shaped thingy(clutch)? yeah that forces the shoes outwards and to rub the hub.
those brake shoes inthe picture expand against the hub. see how when you back pedal or rotate the brake arm that it pushes those shoes against the cone shaped thingy(clutch)? yeah that forces the shoes outwards and to rub the hub.
10-13-09, 05:49 PM
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i understand how a coaster brake works. i've disassembled and repaired them before. i understand the concept of foot goes back - pressure turns screw (driver) - screw drives cone (clutch) - cone pushes shoes outwards onto hub.
i see what ryan is saying about mechanical advantage and i understand that a mechanical advantage is happening, i was just curious as to more explanation as to what exactly this mechanical advantage is and why it works so well.
i also understand the basic concept of mechanical advantage (i think). i understand that, for instance with a lever, with the pivot in the middle, to lift weight (or counteract force) 'x' you need to apply force 'x' to the other side. if you extend the lever out farther on your side, you can apply a force less than 'x' to lift the same weight, compensated by the mechanical advantage of the lever. i understand a lever, i understand a screw, i understand a pulley. i'm not yet understanding a coaster brake (which is obviously more complex)
i see what ryan is saying about mechanical advantage and i understand that a mechanical advantage is happening, i was just curious as to more explanation as to what exactly this mechanical advantage is and why it works so well.
i also understand the basic concept of mechanical advantage (i think). i understand that, for instance with a lever, with the pivot in the middle, to lift weight (or counteract force) 'x' you need to apply force 'x' to the other side. if you extend the lever out farther on your side, you can apply a force less than 'x' to lift the same weight, compensated by the mechanical advantage of the lever. i understand a lever, i understand a screw, i understand a pulley. i'm not yet understanding a coaster brake (which is obviously more complex)
Last edited by wearyourtruth; 10-13-09 at 05:59 PM.
10-15-09, 04:09 AM
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the reason a coaster brake is easier to skid with is, as everyone's said, b/c you have a mechanical advantage. This comes about due to the differences in gearing.
With a fg, with 70 GI, the rear wheel moves almost 3 times faster than the cranks are rotating. So, it takes a heck of a lot of energy to stop the wheel with the relatively small amount of leverage.
A coaster brake, however, is geared to make it easier to stop. The backward movement of the pedals only has to move the pads of the drum brake up to the surface of the drum. My uneducated guess is that the brake pad, being located as close to the drum as is reasonable, would move less than 1mm for every cm that the pedals move backwards.
3:1 gearing --> 1:10 = much easier!
With a fg, with 70 GI, the rear wheel moves almost 3 times faster than the cranks are rotating. So, it takes a heck of a lot of energy to stop the wheel with the relatively small amount of leverage.
A coaster brake, however, is geared to make it easier to stop. The backward movement of the pedals only has to move the pads of the drum brake up to the surface of the drum. My uneducated guess is that the brake pad, being located as close to the drum as is reasonable, would move less than 1mm for every cm that the pedals move backwards.
3:1 gearing --> 1:10 = much easier!
10-15-09, 06:55 AM
#14
Your cog is slipping.
I did the weirdest thing while driving to work this morning. I shifted my transmission with my hand from inside the car.
10-15-09, 09:17 AM
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10-15-09, 10:10 AM
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Found a fixie on CL the other day that was so cheap I just had to buy it. Went to pick it up and it turned out to have a coaster brake. Bought it anyway. Thinking i am going to keep that coaster brake wheel for bar nights and such. Its really kind of fun, thou it makes you look like an ass. But maybe less of an ass than someone with a Track specific frame set up ss.
10-15-09, 11:49 AM
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Isn't there something to be said about the forward momentum of a fixed gear that makes it harder to lock up the wheel? Especially if you don't take enough/any weight off the back.
10-15-09, 12:40 PM
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It is assumed that a bike with a coaster brake would have the same forward momentum.
10-15-09, 12:50 PM
#19
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i understand how a coaster brake works. i've disassembled and repaired them before. i understand the concept of foot goes back - pressure turns screw (driver) - screw drives cone (clutch) - cone pushes shoes outwards onto hub.
i see what ryan is saying about mechanical advantage and i understand that a mechanical advantage is happening, i was just curious as to more explanation as to what exactly this mechanical advantage is and why it works so well.
i also understand the basic concept of mechanical advantage (i think). i understand that, for instance with a lever, with the pivot in the middle, to lift weight (or counteract force) 'x' you need to apply force 'x' to the other side. if you extend the lever out farther on your side, you can apply a force less than 'x' to lift the same weight, compensated by the mechanical advantage of the lever. i understand a lever, i understand a screw, i understand a pulley. i'm not yet understanding a coaster brake (which is obviously more complex)
i see what ryan is saying about mechanical advantage and i understand that a mechanical advantage is happening, i was just curious as to more explanation as to what exactly this mechanical advantage is and why it works so well.
i also understand the basic concept of mechanical advantage (i think). i understand that, for instance with a lever, with the pivot in the middle, to lift weight (or counteract force) 'x' you need to apply force 'x' to the other side. if you extend the lever out farther on your side, you can apply a force less than 'x' to lift the same weight, compensated by the mechanical advantage of the lever. i understand a lever, i understand a screw, i understand a pulley. i'm not yet understanding a coaster brake (which is obviously more complex)
10-15-09, 01:36 PM
#20
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10-15-09, 05:32 PM
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Found a fixie on CL the other day that was so cheap I just had to buy it. Went to pick it up and it turned out to have a coaster brake. Bought it anyway. Thinking i am going to keep that coaster brake wheel for bar nights and such. Its really kind of fun, thou it makes you look like an ass. But maybe less of an ass than someone with a Track specific frame set up ss.
most people don't need a brake for that
10-16-09, 10:26 PM
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I ride a coaster....on a frame with track geo.....I'm f****ing cool
10-16-09, 11:21 PM
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why the hell would you want a coaster brake? its either brakeless or get a decent rim brake or a nice disc brake.
Last edited by feetpower; 10-16-09 at 11:24 PM.
10-17-09, 08:06 AM
#25
Your cog is slipping.
