Disc Brakes

[mountaindew]

What I am looking for is a disc brake that offers a wider gap between rotor and pad. I typically set up a bike to engage the brake where the lever is parallel to the handlebar, so you would think that this would leave a generous space for the rotor. For the record, I have worked on many a brake (hydraulic and mechanical) in a very busy shop, and still haven't seen a brake that allows for a little warp in the rotor. Any feedback would be greatly appreciated, even links to comparison articles.

[Trailer Rails]

That is interesting, I am thinking that if a brake allowes a large gap then it would have slightly less power than a brake that has to be setup closer. I think you need to do some measuring and give us some feedback. I am a fan of what Avid is doing these days in brakes. They seem pretty easy to setup. I think the shorter the brake pad the easier it will be to setup. Rember the XT brakes with the 4 pistons? The long brake pads were harder to keep from rubbing.

[mountaindew]

Yes! Powerful brakes and light, those XT's but always fooling with brake rub. I like Avid's too. They really are tried and true. I just remember the days of being able to pop a spoke and take the barrel adjuster in on my V-levers and limp home with a wobbly wheel. The hard part for me is that if my wheel doesn't seat just right in the drops, I have rub. If my rotor slightly bends, I have rub. I spent years working on every brake imaginable and there really isn't much difference. I think you're right that the tight tolerances make for a powerful brake. I especially notice this on mechanicals. After the pads break in and you are able to run the pads right next to the rotors, there is a monumental difference in feel. I'll try to do some more homework and get back to the subject.

[MileHighMark]

I've got my Avid BB7s setup so that the lever engages very close to the grip/bar.

[mountaindew]

I've got my Avid BB7s setup so that the lever engages very close to the grip/bar.

I find that you lose power when bb7s are set up that way. Has this been your experience? Also, I personally can't set up my brakes that way or my fingers get smooshed. See, what I'm trying to see is whether we couldn't design a brake that operates on a higher ratio so that there is a lot of clearance in the caliper, but you still get that snappy feel of a brake run with low tolerances. Kinda like the difference between Sram and Shimano, 1:1 vs 2:1.

[tryandgetme]

I set my avid BB7's up tight, then if I crunch a rotor I just turn the red knobs (or loosen the bar barrel adjuster) and ride home. Same as I did when I ran v brakes. I almost don't want hydros for the lack of the red knob. It's been good to me.

Apperantly the IRD double bangers use some kind of a floating caliper design that might handle rotor warp better...

[MileHighMark]

I find that you lose power when bb7s are set up that way. Has this been your experience? Also, I personally can't set up my brakes that way or my fingers get smooshed. See, what I'm trying to see is whether we couldn't design a brake that operates on a higher ratio so that there is a lot of clearance in the caliper, but you still get that snappy feel of a brake run with low tolerances. Kinda like the difference between Sram and Shimano, 1:1 vs 2:1.

I have no problem with power with this setup. I run Avid SD-7/Ti levers, and have the modulation adjusted for max power. I only need my middle finger on the lever and it works beautifully. I ran my v-brakes this way, and I moved away from hydraulic discs to the BB7s so that I could get the same feel.

[tryandgetme]

Yeah those SD Ultimate Ti levers sure do rock. Got my front and rear brakes feeling exactly the same even though I've got a long full housing cable to the rear. 185mm rotors, and single finger lockups are easy on any surface.

[Goride]

That is interesting, I am thinking that if a brake allowes a large gap then it would have slightly less power than a brake that has to be setup closer.

Correct.

The reason disc brakes are so powerful is due to their mechanical advantage. A lot of lever movement is translating to just a little bit of pad movement, yielding tons of leverage.

[noob-to-29]

i have the avids mechanical disc brakes on my new fisher 29er cobia and im not sure what model they are that come with the cobia but after i ride just around the neighborhood i always have rub in one spot on the rotor, if i loosen the cable then i have very little brakes

any ideas?

[MileHighMark]

i have the avids mechanical disc brakes on my new fisher 29er cobia and im not sure what model they are that come with the cobia but after i ride just around the neighborhood i always have rub in one spot on the rotor, if i loosen the cable then i have very little brakes

any ideas?

The rotor needs to be "trued." Once that's done, you can adjust the pads via the knobs on the caliper. Cable adjustment shouldn't be used for more/less clearance. You want to take out any slack with the adjuster, and move pads in/out via the knob(s).

Here's the manual for your brakes:

http://www.sram.com/_media/techdocs/BB5%20User%20Manual.pdf

[Spatafore]

i have the avids mechanical disc brakes on my new fisher 29er cobia and im not sure what model they are that come with the cobia but after i ride just around the neighborhood i always have rub in one spot on the rotor, if i loosen the cable then i have very little brakes

any ideas?

This is not the preferred method but when my rotor had been knocked out of shape, I have just bent it back with my thumbs while the wheel is still on the bike. When you look down at the caliper, you can see the tolerances on both sides of the rotor. Find the bent section simply by rotating the wheel until you can see it touch one of the pads. Rotate it a little more to bring the bent spot out from between the caliper. A couple pushes on the rotor and a couple spins of the wheel and you should be done.