Cantilever brakes centering

[Jimmy Doug]

Hi

I've never been much of a bike mechanic. I can do basic things, but there are some tasks that I never seem to achieve without taking my bike to the local shop. One of these is centering the cantilever brakes on my touring bike. I've spent all morning reading about it on sites like Sheldon Brown, looking at videos, taking the brakes apart and greasing/oiling, adjusting and readjusting the little tension screws, moving the wheel slightly left or right ... but no matter what I do I can't for the life of me get it right. Either the brakes rub on one (or both) sides, or they're too loose. What I have noticed is that despite the fact that the pads are very close to the rim the cable is very loose:

I've also noticed that the cable seems to have come out of the cable carrier but I can't figure out how to put it back in place, or which slot to use:

The brakes are really close to the rim, yet when I pull on the brake lever I can touch the handlebars with it ... and still there's pad rub:

I really hope one of you mechanically minded people can help because it's driving me round the bend!

Cheers

 

[fossyant]

Cable needs to run via the smaller hole on the straddle wire (the wire that links the canti's).

Looking at the cables, I'd say you need new outers and inners - this will solve your problems - sounds like they are sticky.

Once you remove the old cables, check both canti's pivot smoothly - if not remove and clean (dead easy). - From your last photo you can see the grub screws that adjust the tension.

But get new cables first as they look old and most likely mucky inside.

 

[Jimmy Doug]

Thanks very much for your reply. I was wondering if it could be due to old and dirty cables and housings, but to me they appeared to be in OK condition (no fraying or rust) - but I guess after 7000 km it's perhaps overdue. I'm not sure I can change the front housings though: they appear to form an integral part of the front shifters and I don't think they can be removed.
Took the bike for a test ride - it actually seemed much better, so it looks like my hard work today has achieved something. When the bike is on the workstand the brake pads do rub as I said - but they seem OK on the road and the braking at the rear is much improved.

 

[Baggy]

If your workstand clamps the top tube it might pinch the cable and make the pads rub. Cantis are evil!

 

[Jimmy Doug]

Yes, I discovered that the hard way! Now I clamp the seat post.