/ Adjusting / replacing brake pads

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Ramblin dave - on 13 Nov 2012
Another noobish bike maintenance question...

I'm replacing a horribly worn pair of brake pads today. I always find that replacing and adjusting brake pads is about the most annoying and fiddly task out there - you've got to adjust them to millimetre precision in about six degrees of freedom, and having got them just right you then have to tighten them up by cranking a single nut that runs through the middle of the whole arrangement without upsetting any of your delicate adjustments...

It always seems to take me ages to get it right - is there a trick to it that I don't know? Or is it something that you just get the knack of? Or is it just an inherently annoying task?

(My brakes look quite a lot like this:
http://en.wikipedia.org/wiki/File:Cantilever_brake.JPG
fwiw...)

Thanks!
Jamming Dodger on 13 Nov 2012
In reply to Ramblin dave: Its an inherently annoying task and once I trashed a set of cantis by overtightening the micro adjust bolt. Worked out ok in the end cause they were sh*t brakes anyway and now I pay someone else a tiny amount to do it properly in about two minutes.
Martin W on 13 Nov 2012
In reply to Ramblin dave: Is the Park Tool cantilever brake service guide http://www.parktool.com/blog/repair-help/cantilever-brake-service any help? And there's always Sheldon Brown http://sheldonbrown.com/rim-brakes.html#shoeadj of course.
balmybaldwin - on 13 Nov 2012
In reply to Ramblin dave:

Theeasiest way I found with those types of brakes was

Firstly check that the wheel was true to within about 1mm wobble.

Second, undo the bolts on both sides, and then wind the brake adjustment screw on the levers out as far as they can go whilst still on the thread

Third, get a piece of card about 1mm thick to wedge under one end of each block to allow for toe-in.

Fourth, hold the pads against the rim (and card) making sure that the shaft/bolts on the pads are perpendicular to the rim

Fifth, whilst still holding the pads as hard as you can, tighten the bolts for the pads to a reasonable tightness on each side, then use an allen key in one side to counter the movement of the spanner on the other while you fully tighten each pad

Sixth, pull out the card, and wind in the adjustment bolts on the levers until the pads are clear of the rim so the wheel can rotate without rubbing.

Takes about 5 minutes per set and is pretty easy to get right - just remember to make sure the pads are vertically central on the rim surface so they don't rub the tyre or risk slipping off the rim towards the spokes.
ChrisJD on 13 Nov 2012
In reply to Ramblin dave:

It is a thankless task. You have my full sympathy.

<shudders at the memory of fiddling with canti brakes>
Ramblin dave - on 13 Nov 2012
In reply to balmybaldwin:
Wow, thanks, I'll give that a try!

Thanks everyone else, too...
Ramblin dave - on 14 Nov 2012
In reply to Ramblin dave:
Following that advice certainly helped! I wouldn't say it was a five minute job, but it was certainly easier than usual.

One modification was to wrap a small elastic band round the back of the brake pad as a shim, because it stays there rather more reliably than a piece of cardboard.

Thanks!
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balmybaldwin - on 14 Nov 2012
In reply to Ramblin dave:

Good stuff, and a fair improvement!

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