ruirui

my spring adjuster on my cantilever is cracked. i'm still able stop, but just doesn't stop all the way. it seems like it just slows the bike down but if i do any sudden stop, it won't stop on a dime. so where can i go to replace this part? i have attached a pic from Sheldon Brown's Adjusting Cantilever Brakes article.

also, i noticed that on the side of my rim, there are a lot of brake marks, so i'm thinking maybe the brake pads are harden and dead. any ideas on where i can get this part replaced?

khuon

Are you sure the spring adjuster is the culprit? The spring adjuster increases or decreases tension on the return spring.

halfspeed

You can find the spring adjuster at your LBS. The plastic shell seems to crack pretty easily. Your LBS will have the right pads too. This kind of canti can be tricky to adjust just right. It's not just a matter of dropping in the new parts and riding away.

siggy_lxvi

I dealt with this problem on my Bianchi by wrapping the plastic shell of the adjuster with two or three layers of duct tape cut to the proper width. The grey is the same color as the other housings, so one doesn't notice unless one is looking for the tape. (In fact, this was only going to be a temporary fix, but I'd forgotten about it until you brought it up)

Siggy

ruirui

yup.. cuz when i squeeze the rear brake... it wouldn't tighten up, but instead i see the crack in the plastic get bigger and bigger. it's cracked all the way through.. so right now it's being taped up.


yup that's what i did for a while.. till i try to brake really hard today to stop at a red light... i didn't fully stop.. i rolled to a stop. haha

rui

khuon

Well, the crack is getting bigger because the spring inside it is compressing and thus pushing out the plastic cover. This is purely a cosmetic issue unless the spring itself is split somehow. I however doubt this is truly effecting your braking. Even if you had no return spring at all, you would still be able to apply the same braking effort... of course your brake arms wouldn't retract properly from the rim. Unless the return sprint was somehow preventing the brake arms from reaching the rim with a sufficient amount of force, I think you're looking in the wrong place. I think you may need to play with your cable tension. Are you bottoming out the brake levers before you can apply sufficient force? If it is indeed a misadjusted return spring then you need to back off the tension. However, I have yet to see a cantilever return spring that even when fully tensioned applied enough of a force that I could not overcome it when squeezing the brake levers.

ruirui

khuon, your right about that part. the spring itself it ok.. it's not retracting that much, therefore the brake pad tends to touch the rim. as for the brake lever.. when i squeeze to about 75% then the brakes starts to be applied. i have to figure out how to adjust the brake cables.. because it does seem like it's loose. the brake lever part has a knob thingy that i can pull outwards and turn.. but nothing. what to do??? thus far foot brakes seems to work.. hehe.

Avalanche325

Yes, this spring pulls the brake back open when you let go. So with this being cracked, your brakes may be dragging, but this will not affect stopping power.

ruirui

in that case gotta go visit my LBS for replacement parts then..

khuon

It sounds like your pads are worn. Perhaps you need new ones or perhaps you've just got really slack cables. To take care of the cable slack... referring to your previous picture: You need to loosen the anchor bolt and pull more cable then retighten the bolt. You may also need to align the pads properly. A good place to look for more detail on how to work on cantilever brakes can be found on the Park Tool website.

ruirui

khuon, thank you soo much! perfect... now i'm going to do that after i get home from work. hopefully tomorrow's commute will have better stopping power.. hehe

*EDIT* btw, i just checked my pads... they still look new and still have plenty of padding. could it be that it's no longer good due to being old and hard?

cheers,
rui

Avalanche325

Your pads may just be glazed. If they look shiney, just hit them with some sandpaper, then you have a like new braking surface.

ruirui

cool! i'll check up on that as well tonight. what about those black brake marks on the side of the rim? how can i clean that up?

Retro Grouch 

That's a common warranty issue. Shimano will send the replacement parts to virtually any LBS FREE! Now all that you have to do is to find an LBS who will give them to you for what they paid for them.

The work-around temporary fix is to wrap a piece of wire around the spring retainer and twist it tight to hold the cracked plastic housing together.

Rev.Chuck

We give them out, the spring cups, for free and install them for $10

ruirui

well, my rockhopper is pretty old... guessing that it's probably 10yrs old or so. i don't think there is any more warranties anymore.

Rev. Chuck, if you guys give them for free, can you send me two of them for the rear? i'll pay for postage... right now i am using some electric tape wrapped around it. but's it's starting to come apart again

rui

Rev.Chuck

Try a local shop and if they will not give them to you PM me with your address and I will send you a pair.

ruirui

thank you Rev. Chuck. I'm gonna check with my LBS friday nite after work. hopefully they'll be in a giving mood. if not, i'll pm you. thank you. :d

rui

CRUM

I am sure it is. I ordered hundereds of extra springs and covers from Shimano when they came out with this brake. The plastic retainer will always break, it is just a matter of when. Now that I have no more of them, I came up with a way to fix them. Take them off the brake. With a triangular file, file a groove all the way around the circumference of the plastic retainer, just under the spring adjusting screw. Take some baling wire and place around the plastic retainer in the groove you filed. Then twist the ends together several times. Cut the excess wire and you retainer is fixed. The fix lasts pretty well and only takes me a few moments. I have kept many of these brakes working this way.

Of course the best solution is new brakes without the damn plastic spring retainer. These were the worst Canti's Shimano ever came out with. They stopped okay, but the plastic retainers were a very bad idea.

khuon

I still don't see how the return spring has any bearing on applying sufficient braking force much less how a cracked plastic spring cover has any effect at all.

CRUM

Part of the power transfer aspect of the brake arm is also performed by the spring found under the arm, besides it's duty as the return spring. When the plastic retainer cracks, the force of braking is diminished greatly when the retainer opens up as the brake is applied. Either fix the crack, find a replacement retainer, or replace the brakes. Those are your only alternatives to re-capturing the braking power you once had. And since one has cracked, I would closely examine all retainers, not just the adjustment ones. And be careful to get the right one. Shimano had two versions of this retainer and they do not co-mingle well.

ruirui

crum.. i will check the other retainers as well. i haven't had the chance to go to my lbs.. so hopefully tomorrow. i'm currently dying from hay fever..