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Beater bike brake issues

Old 10-03-12, 03:42 PM
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bagster
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Beater bike brake issues

My beater is a 1980's model GT mountain bike. I replaced the original brakes with some Nashbar "J" brakes, or side-pull brakes as they are sometimes called. They work perfectly on the work stand, but are all but worthless when used while riding. My guess is the levers aren't generating enough force, but I am far from being a bike mechanic. Any suggestions?
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Old 10-03-12, 03:53 PM
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What kind of brakes? Do you have apic or a link? Do you have steel or alloy rims?


These? You put these on a MTB frame and they reach the wheels?

Nashbar Jail Brake Road Bike Brake Calipers

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Old 10-03-12, 04:40 PM
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There's an easy way to check for correctly matched levers and brakes. With a correct match, the shoes will close about 1/8"max per side or 1/4" total before the lever touches the bar

It's simple leverage, travel vs, force. So if your brake shoes open 1/8" or more per side your levers do in fact lack leverage. OTOH, if the brakes are nicely adjusted and close 1/16" per side or less in half the lever's travel, you won't be able to use more leverage, and need to look elsewhere for your problem.

Note, that replacing cantis or V-brakes on a mtn frame involves large calipers. Even if the leverage is correct, there'll be a decent amount of flex in the arms and braking will be poor. That's why only bottom end 26" mtn bikes come with caliper brakes in the first place. The Canti's or V-brakes are inherently more expensive to the manufacturer, involving mounting the bosses on the fork. They weren't used for style, but because of performance.

If you have canti bosses on the fork, consider going back to canti or V-brakes.
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Old 10-03-12, 05:23 PM
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Originally Posted by FBinNY View Post
There's an easy way to check for correctly matched levers and brakes. With a correct match, the shoes will close about 1/8"max per side or 1/4" total before the lever touches the bar

It's simple leverage, travel vs, force. So if your brake shoes open 1/8" or more per side your levers do in fact lack leverage. OTOH, if the brakes are nicely adjusted and close 1/16" per side or less in half the lever's travel, you won't be able to use more leverage, and need to look elsewhere for your problem.

Note, that replacing cantis or V-brakes on a mtn frame involves large calipers. Even if the leverage is correct, there'll be a decent amount of flex in the arms and braking will be poor. That's why only bottom end 26" mtn bikes come with caliper brakes in the first place. The Canti's or V-brakes are inherently more expensive to the manufacturer, involving mounting the bosses on the fork. They weren't used for style, but because of performance.

If you have canti bosses on the fork, consider going back to canti or V-brakes.
I can just slide a playing card between my rim and pads. I had the same type brake put on my regular mt. bike--1995 Cannondale F60--and they will put you over the handlebars if you're not careful. However, these brakes are the better quality Shimano Deore. So are you saying that if the brakes on the beater are adjusted that close to the rims, then leverage is not the problem?
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Old 10-03-12, 06:43 PM
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If they're that close, and there's still decent throw on the lever, then yes you have typical or better leverage. As I said, your issue is rigidity because of the length of the arms.
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Old 10-03-12, 09:15 PM
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I am still trying to figure out why one would want side pull brakes on a mountain bike in the first place.
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Old 10-03-12, 09:33 PM
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Originally Posted by chriskmurray View Post
I am still trying to figure out why one would want side pull brakes on a mountain bike in the first place.
Ours is not to reason why.....
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Old 10-03-12, 10:06 PM
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Originally Posted by bagster View Post
I had the same type brake put on my regular mt. bike--1995 Cannondale F60--and they will put you over the handlebars if you're not careful. However, these brakes are the better quality Shimano Deore.
I don't think we're talking sidepulls here folks; these are Vs. I bet OP's looking at the noodle for his 'side-pull' call.

Try scuffing the pad faces up on some concrete for a start.
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