asolodin

Well, the season is almost over (though it snowed here last night and temps were in teens this morning) but I need a set of good winter-resistant disc brakes on my 29er commuter. My rear brake (Shimano mechanical BR-M495) has disintegrated when I tried to clean it last weekend. I ride 20+mi daily throughout most of the winter in St Paul, MN. Normally, I flush my whole bike including calipers/rotors with warm water once a week. Last week I noticed that the pads in the rear brake were not disengaging as well as before, so I decided to take them out and clean them. Once I took them out, to my horror, the entire inside of the caliper was covered in half-baked in white powdery stuff which I took to be Al2O3 (aka aluminum oxide). The bolt/pin that holds the pads in place has started to rust as well, which contributed to the pads not moving freely. The pads themselves were in ok condition. So I tried to clean the inside of the caliper, and as part of that I used the pad-in/out adjusting bolts to move the pad adjusters in/out. At some point I must have moved the main (front) adjuster a bit too far and a rubber o-ring/seal came out and absolutely refused to go back in. The inner adjuster was so ceased up, I stripped the adjusting hole. To make a long story short, I threw the thing against the wall in frustration . Anyway, what I am looking is something more salt resistant and simpler to maintain as well. It would be nice if the insides of the calipers were anodized (unlike the BR-495) and used stainless hardware as much as possible. Mechanical preferable but hydraulics are ok. It helps if they don't cost an arm and a leg either. Anybody got any suggestions? Thanks in advance!

AEO

that white stuff was salt. flushing it out with water might not have been the best thing to do.
alcohol is the suggested course for cleaning parts that can rust.

there's no mechanical disc brake better than the avid BB7

tsl

That may be, but the rear one on my bike started having corrosion issues this past season, its second winter. I'm having two problems. The inner (fixed pad) adjuster seized, and the pads don't release fully. The side deep inside the caliper maintains contact with the rotor (making annoying noises) while the outer part retracts as it should.

I get the worst of both worlds--a dragging brake that's ineffective when applied. I'm waiting until I know salt season is over before messing with it.

My bike gets rinsed every night when I come home. It hangs next to the radiator to dry. Our city used so much road salt this year that it's still fizzing out of my wheels around the spoke nipples and valve stem. That has never happened before, on either this bike last year, or the bike I had before.

Sheer speculation follows: My guess is that the horizontal mounting of the rear caliper is partly to blame. Unless I were to flip the bike over (or remove the caliper entirely), I can't really flush it out.

The front one--mounted vertically--rinses out just fine and dries in no time. The rear gets much more crap splashed up inside it too, which also seems to get set stuck up in there, and it never seems to dry out either.

Edit: Word is that there's now a rear-specific BB7 caliper. I'm considering replacing the current one rather than rebuilding it. It may solve other issues I have with only the rear brake.

Then again, maybe it's just the nature of the beast. Three bikes with disc, road caliper and V-brake, all have problems with only the rear brake. What's up with that?

AEO

rear brake: longer cable, more slack, more resistance and sloppier.

the only fix I know of is making the return spring in the brake arms (canti or V only)or lever stronger by bending the spring or using the next set of adjustment holes.
of course it makes it harder to actuate the brake itself, but at least the brakes will open up properly.

jgedwa

A couple of comments about what tsl wrote:

-You happen to ask as much of your bike equipment as any rider around. You ride a lot. You ride in all weather. And, you keep using it all through the snowy/salty Winter. I am not at all surprised that you find the limits of components much sooner than any of the rest of us. (I mean all this as a compliment, btw.) Nevertheless, by most all reports (including my own), the BB7's do a remarkably consistent job of doing their job. Put another way, I am not overly confident that any braking system could last for too long under the conditions you ride.

-I wonder if, because the rear brakes are used less than the fronts, they don't tend to seize up on you more. Constant use does wonders for keeping corrosion at bay in a lot of applications. Maybe they get packed full of crud, but do not cut through it as much as the fronts.

jim

tsl

Absolutely, I agree. I didn't mean to imply that I'm disappointed in the BB7s.

Let me put it another way: I'm amazed that they didn't need to be overhauled at the end of *last* season. Two Rochester winters between overhauls is really sumpin'. Hell, most automotive brake systems don't make it through two Rochester winters--and seized calipers are their number one problem too.

The point I was trying to make for the OP, is that winter is really tough on components. It's not necessarily that the Shimano brake is a poor design--I'm not qualified to evaluate that--but if, as AEO states, the BB7 is the best mechanical disk brake out there, it too is not immune to corrosion.

ghettocruiser

I have three winters of salty daily commutes on XT hydraulics. Trouble-free.

Hayes mag disks were just as good before them.

I do rinse them often, but nothing more than that.

asolodin

AEO: the white stuff was not salt as it didn't dissolve in water. I think the insides of the brake calipers are not anodized or even painted, i.e. it is bare Al/alloy. Bathe that in salty water for a while, see what happens. And I have made the same observation as tsl in that only the rear brake has this problem, the front one works fine through the second season already. ghettocruiser: I've been reading lots of reviews lately and I am going to try XT hydraulics for next season. Thank you all for your thoughtful suggestions.

AEO

some brine solutions that get sprayed on the road really eat away at metals, be it aluminum or steel.
and yes, those bare bits really suffer as a result. I have a pair of bare canti brakes that seem to be permanently stained from the road brine.

my observations with winter riding and why a rear disk would get rusted quicker than the front is because of full coverage fenders.

the front fender just kicks out the slop, but for the rear the slop has to make a longer travel down to the bottom and a lot of it just falls onto the drive train and hubs. fork placement and chainstay placement adds to this effect too. fork is behind the hub and the chainstay is in front of the hub.

CastIron

The BB7's, based on my teardown in their first winter, were not built with road salt in mind. They are a great brake, but were I to do it again, I'd tear 'em apart before the install and apply copius amounts of grease. Avid really screwed the pooch by assembling these things without proper compounds inside.

The pads were renewed with a steel brush and some 60 grit sandpaper. Like new.

jgedwa

Hmmm. Should I do this? Has anyone else done it? Is it possible they are left ungreased so keep grit buildup to a minimum? I am not suggesting that you should not do it, but I am curious to hear more about it.

jim

CastIron

The odds of grit contamination are much lower than salt corrosion since the particles in play are larger and fewer. Further, a good waterproof grease would limit it as well, acting as a viscous seal. It's not a perfect solution, but after a total disassembly (the PDF is on the Avid site), it seemed quite clear that it wasn't a design problem I was lamenting.

andrelam

With all the issues you experience with the disk brakes, maybe V-brakes aren't so bad after all. When I got my bike back in 2007 I could only spend about $550 and the LBS didn't like the disk brakes that came on bikes that were priced much less than $800. At first I was dissapointed that I couldn't afford a bike with disk brakes, but so far the V brakes have made it through two Buffalo winters and only needed a tiny bit of cleaning. I did have some minor issues back in January where the brakes were not pulling away from the rim properly. One bolt per side for the brakes took them appart. A liberal application of some liquid wrench and a little moving of parts made everyhting work perfectly again. Suprisingly the V-brakes are have done a perfectly fine job of stopping me anytime I needed to. For my next "dream" bike disk brakes were definitely going to be on the list... maybe I'll just remain happy with simple v-brakes.

Happy riding,
André