Adjusting Cantilever Brakes (at my wit's end!)

ChrisEyles

Veteran
Location
Devon
I was fiddling around in the garage with my bikes the other day, and my wife asked if I could have a look at the 1990s era (I guess) Shimano V-brakes on her hybrid. "No problem!", said I. However, an hour of fiddling around with those damned adjuster screws later, and I'm still not happy with them :sad:

I'm happy with the brake pad alignment, and can certainly get the wheel to lock with a nice firm response in the lever. The problem is the canti arms aren't releasing as well as they might, and try as I might, one end stays rubbing on the wheel after releasing the brake.

I've already given them a squirt of GT85 and a good old wiggle back and forth - the springs feel strong and seem do be doing what they should. I've then adjusted the little screws on the canti arms (many, many times now) so that the two arms move equal amounts when applying/releasing the brakes. This works for a few times, then the canti arms start going off-centre when the brake is released, leaving one of the pads rubbing on the rim. This only happens on the front brake, the rear one was quite easy to adjust and is now working perfectly.

Wifey is happy that the brakes are working much better, and is content with reaching down the nudge the front brake away from the rim after use... but this is obviously not ideal, and it is seriously niggling at me that I can't get the bloomin' things to work as they should!

Anyone got any tips, or am I missing something that should be obvious?
 

ayceejay

Guru
Location
Rural Quebec
Do those little screws do anything when you turn them? ou might also want to remove the arms from the pegs on the forks and grease the pegs, if there is more than one hole to connect the arms to theses screws and cable tension are your adjustment options 0 if you have more than one hole you can try different combinations. Rest assured you are not the only one with canti problems as they are a well known hassle.
 
OP
ChrisEyles

ChrisEyles

Veteran
Location
Devon
I debated taking the arms off the bosses to re-grease them, but it seems to me that both arms are moving freely, and that the springs both give a nice positive return action (I checked this by unhooking the quick release and wiggling them around when I squirted in some GT85).

There's only one hole in each arm, so that is a fixed point.

The adjustment screws are definitely functioning - by moving them to their limits I can make it so that either the left or the right arm does all the movement on applying/releasing the brake. With careful adjustment I seem to be able to get both arms moving equally, and centred properly... then a few applications of the brake and it's back to rubbing on one side! Gah!

I haven't played around with the cable tension via the barrel adjuster yet, but I think this is OK, based on the fact that I can generate strong braking force without the levers feeling "sloppy".

Glad to hear I'm not the only one having difficulty though! I didn't encounter anything anywhere near this fiddly on a full strip down and rebuild of my 1950s roadster, and that included setting up the rod brakes!
 
Location
Loch side.
Clean and grease the pivots and bushings as suggested. Then, unclip the springs and bend them open a bit more. If there is more tension in the arms, they respond better to screw input. Remember that the screws work in unison. If you turn one in, you must turn the opposite one out. There should be no need to have either at their limit of travel. Canti's are a bit of a fiddle but they work well.
 

Andy_R

Hard of hearing..I said Herd of Herring..oh FFS..
Location
County Durham
As the springs are nice and strong, and the canti's move freely on the pivots, the next thing I'd check would be the cable. Is it running freely in the cable housing?
 
OP
ChrisEyles

ChrisEyles

Veteran
Location
Devon
Thanks for the feedback all :smile:

I've not checked the cable itself, so might have a look at this. I'd rather not disassemble to re-grease the pivots if I can avoid it, but if the next session of fettling doesn't work out I'll give it a go!

Yellow Saddle, thanks a lot for the info - I didn't realise the screws should be adjusted in tandem, I was working on these one at a time. This is the first thing I'll try when I next get a look at the bike.
 
Location
Loch side.
I'd use Copaslip on the pivots.
It is obviously better than no grease at all but why recommend a product that is not designed to lubricate? It is a plain bearing (bushing) after all.
 

S.Giles

Guest
I can adjust my Vee brakes one day so that both pads release an equal distance from the rims. The next day, one pad remains in very light contact with the rim after releasing the brake lever, all the movement being on the opposite side. It's not worth adjusting it again, because a day later it will be out of balance yet again.

This used to bother me, but it doesn't seem to impede the bike at all when being ridden so I (ever the pragmatist) just ignore it now.
 

mrandmrspoves

Middle aged bald git.
Location
Narfuk
If the pivots are nice and smooth and the springs are strong I would think further fine adjustment of the tension screws - but I have frequently found that the real issue is cable routing.
 
OP
ChrisEyles

ChrisEyles

Veteran
Location
Devon
I can adjust my Vee brakes one day so that both pads release an equal distance from the rims. The next day, one pad remains in very light contact with the rim after releasing the brake lever, all the movement being on the opposite side. It's not worth adjusting it again, because a day later it will be out of balance yet again.

This used to bother me, but it doesn't seem to impede the bike at all when being ridden so I (ever the pragmatist) just ignore it now.
This is pretty much exactly what I found - and pretty much exactly my wife's attitude to the problem! I'd really like to get it fixed though, as much for my own satisfaction as anything else!

I'm confused. Are we talking about cantilevers or V-brakes ?
As far as I understand it, V-brakes are just side-pull cantilevers. I have centre-pull cantilevers on my touring bike, but these are working fine with no rubbing (touch wood), so I will leave those adjustment screws well alone!

If the pivots are nice and smooth and the springs are strong I would think further fine adjustment of the tension screws - but I have frequently found that the real issue is cable routing.
*Fine* is the operative word here! When I get around to having another look, I'll definitely check the cable smoothness/routing, thanks for the suggestion.
 

raleighnut

Legendary Member
Location
On 3 Wheels
It is obviously better than no grease at all but why recommend a product that is not designed to lubricate? It is a plain bearing (bushing) after all.
I'll change the post then...........I use Copaslip on my pivots and have never had a problem. Grease tends to be washed away by water sprayed onto the pivots by the brake blocks leading to corrosion on the Steel pivot pins.
Plus the bushing is in Bronze (an alloy of Copper and Tin) or Brass (an alloy of Copper and Zinc) on cheaper brakes.
Happy now?
 
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