disc brake question

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bikefind
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I mountain bike on a rockhopper comp disc 29er – it’s the first/only bike I’ve had with disc brakes so far. I think for the first season or so, it was fine. But after that, I’ve only been able to ride for about two hours max, and my brakes (BB-5’s) are gone. At some point I usually catch that they’ve started to loosen up and I turn the dial (the one down on the brake mechanism itself – not talking about a barrel adjuster here) a couple notches and that takes care of things for another hour or two of riding.

Other than that, I completely love this bike. I’ve taken it to two mechanics so far, one of whom is really sharp, but I’m still dealing with this. The bike shop where I bought the bike tightened up my cables when I first started having this problem, which basically bought me a little more time before I run out of clicks on the dial.

I don’t know why this is happening. I do use my brakes more than your typical hardcore mountain bike rider (I like to climb hills, but am not crazy about the idea of flying down the other side as fast as the bike will go) – is it likely that I’m just wearing them out really fast? (Well, not *out*. the pads are still good. Wearing them loose I guess I mean.)

I know one other person this happens to, and she’s also not a real fast descent type.

It’s been suggested that I upgrade to BB-7’s. Does anyone here have knowledge of these? Is it likely that the BB-5’s just suck and BB-7’s will do the trick? (I’m leery of assuming this, because I feel like I’d have heard more people dissing them.) Or is it more likely that my riding style just beats the crap out of the brakes and would stop serving me quickly no matter how far I upgrade?* I’m also looking at a bike with hydraulic disc brakes, so I think it would be great if I could learn what’s happening before making a decision. If I’m going to make that bike’s brakes suck like I’ve made this one’s, maybe I should change my plans.

*Or some other explanation I haven’t thought of?

Thanks for reading.


cburch
Participant
#

what you are talking about is called brake fade.

a few things:

1) check the pads for wear. unlike the avid hydraulic discs, their mechanical discs don’t auto adjust as they wear, thats what the inboard and outboard dials are for.

2)bb7s are a LOT nicer than bb5s for very little additional cost. upgrade them, its worth it. if you sell the bike and get a new one the resale will be better with the 7s too. i use them on my spare downhill bike and get very little fade (i do use 8″ rotors on that bike though)

3)try new cables and higher quality housing. if the cables are old and worn out or the housing sucks you could be losing power to cable stretch or housing compression.

4)try larger rotors. more than likely you have 6″ rotors. if none of the above fixes the problem try stepping up to 7″ rotors. you will need new adaptors for the calipers and should probably have someone with experience change everything out for you, but its pretty straightforward.


bikefind
Participant
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Thanks cburch!

[edited to add]

I’ll try your suggestions in order. I’m thinking the cables should still be pretty good – I bought the bike new 2 years ago and have spent around 150 hours on it. Correct me if I’m underestimating how long it takes to wear out a cable?


bikefind
Participant
#

Got my bb7’s, and got a bigger rotor for the front brake at the same time – so far so good – the bike seems happy to stop for me now whenever I want. Ah the luxury.

Even if I get the new bike, I’ll probably hold onto this one, but I’d still like to pick your brain cburch – how much would you up the resale (asking) price with the new brakes?

And thanks again for the information.


cburch
Participant
#

half the cost of the nicer parts at retail, not including the labor charges. so probably $80-100 depending on where you got everything. if you sell it fairly soon i mean. the added value will depreciate every year, just like the rest of the bike.

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