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So, a colleague road to work and says his brakes are rubbing and then shows me his bike. Seems one of the "arms" has been rotated or moved in and is constantly in contact with the rim. I've got no clue how to sort it (if it was mine I'd have a crack at it tho). If this was a normal road rim brake I'd just rotate the whole unit to re-centre the brakes but am lost on this. Any ideas?
Have you got a pic? It's quite hard to tell from your description. Also, is it a HS33?
If so, it sounds like it might be one of the 'elbows' that sit against the inner surface of the seat-stays. An easy fix it if is. Loosen off the top bolt on the main clamp (You'll need to undo the quick release lever if it's on that side). You can then rotate the 'elbow' back so that it braces against the seat-stay, and re-tighten it.
While your there it's worth checking that the rest of the piston body is alligned nicely with the rim and the pad makes square contact. Easy enough to do when the clamp's loosened off anyway.
Hope that helps!
Edit: talking about a rear there obviously (My excuse is that's where mine is so I was looking at it for reference!), no experience of working with one on the front, but I would imagine the set-up is much the same. I'm sure someone more knowledgable will be along to correct me soon! 🙂
It's the left hand arm (right hand as you look at it obviously) that's the problem
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It looks like the quick-release has come off the bolt somehow.
Flick the quick-release lever down, the whole left side be able to move. Place the quick-release section over the dark gray bolt you can see in this pic, the bolt locates through the hole in the silver 'body' of the quick-release section. Then move the lever back into the upright position locking the whole assembly.
You might need to do some fine tuning to line the pad up properly, but that should solve the problem by the looks of it. Worth checking the bolt for the quick-release is tight too.
I think it's just a case of undoing the QR and re-aligning isn't it?
The arch needs to be hooked over the corresponding bolt on the drive side brake too. Just attack it with allen keys, you can't really go wrong. *Awaits follow up picture with oil all over the floor and a brake lever sticking out of a child's eye.*
No allen keys or multi-tool at work. He's leaving it here for me for next week so prepare for imminent child blinding.
Yup, QR has come off - push the lever down, slide the thing onto the canti boss (making sure the bridge lines up as well), and then pus the lever up to clamp it on.