How do I increase the clearance on rear rim brake?

[fair weather cyclist]

Hi guys, i'm having a wee problem with my partner's bike. The clearance between rear wheel/tyre and the rear rim brake is minimal, I'd say no more than 1mm, which makes it a problem when little pebbles get caught in the tyre as they scratch the brake. You can see below (bike upside down) all the black paint has come off.

This is the brake, it's a tektro so not great but good enough (eventually I'll buy a proper 105 brake set). Is there anything I can do to increase the clearance? Any of those wee bolts I can tighten/loosen/play around with?

This one instead is the front brake and as you can see (barely, apologies for the bad quality photo) there's plenty of clearance so no issues there.

Last thing, the tyres are 28mm which I think are a bit of a stretch for rim brakes, regardless of what the Giant website says. In the absence of other solutions, would switching to a 25mm tyre improve the situation?

 

[Sharky]

Bit confused as to exactly what the issues are.
Tektro brakes are perfectly adequate as rim brakes go. If you ever ride with weinmann side pull brakes, you would appreciate the Tektro brakes.

If the shoes are too close to the rims, you need to loosen the cable a bit. The adjuster looks to be screwed fully in, so you can't use that to slacken the cable.

28mm tyres are perfectly OK with rim brakes. Only restriction is clearance between tyre and forks/frame.

 

[I like Skol]

Your pictures are a bit misleading as you show the underside of the rear brake which is a bit polished, and the clearance at the front brake which despite a slightly skewed picture angle appears to show adequate clearance.

Can you take a pic of the clearance at the rear brake with the tyre fitted, I suspect this is tighter than the front. IMO the solution is to downsize the tyres.

 

[fair weather cyclist]

Your pictures are a bit misleading as you show the underside of the rear brake which is a bit polished, and the clearance at the front brake which despite a slightly skewed picture angle appears to show adequate clearance.

Can you take a pic of the clearance at the rear brake with the tyre fitted, I suspect this is tighter than the front. IMO the solution is to downsize the tyres.

Yes the front brake has great clearance, I'd say there are at least 5mm between top of the tyre and brake.

The problem is the rear brake where clearance is 1mm at most. I'd like to know if and what I need to tweak/manipulate on the tektro brake to increase the clearance between rear brake and tyre.

I'll try to get a photo of the rear tyre when I take the bike off the turbo.

 

[cougie uk]

Looks like the frame isn't designed for 28mm tyres.

Either live with some scratches on the brake and the possibility of it locking up if it gets wedged or use 25mm tyres.

This is one advantage for disc wheels - better tyre clearance.

 

[Cycleops]

Probably because the bike originally had 25c tyres?
If you want more clearance the only solution is to swap back.

 

[fair weather cyclist]

Probably because the bike originally had 25c tyres?
If you want more clearance the only solution is to swap back.

That's what I thought, but also this giant bike has giant tyres so chances are they're the stock tyres.

 

[Cycleops]

In which case your choices are:
Change to 25c tyres
Change the brakes to ones with a non applied silver finish
Touch in the scratches with black paint

 

[cougie uk]

Too giant I'm afraid.

 

[MichaelW2]

Thinner tyre at the rear. Or hacksaw and reweld the seatstay bridge to its correct position higher up.

 

[figbat]

A different tyre make might have a different profile but this will be trial and error at best. A different caliper might have less material around the mounting area but again this is conjecture and would require a lot of measuring and testing. Narrower tyres are the easiest fix.

 

[fair weather cyclist]

A different tyre make might have a different profile but this will be trial and error at best. A different caliper might have less material around the mounting area but again this is conjecture and would require a lot of measuring and testing. Narrower tyres are the easiest fix.

I'll try narrower tyres.

I just checked and the current giant tyres are 28mm and look bigger than the 28mm conti gp5000 I have on another bike. I'll get some 25mm continental and hope for the best.

 

[cougie uk]

Depends on rim width too. Wider rims will flatten the height down.

 

[DaveReading]

Saw a few mm off the brake blocks ?

 

[fair weather cyclist]

Depends on rim width too. Wider rims will flatten the height down.

Yes, possibly. I'm trying to find out the width of the rim.