How do I increase the clearance on rear rim brake?

[fair weather cyclist]

If what the OP is asking is "Is there a dedicated adjustment in the brakes which enables me to raise the entire assembly away from the tyre?" then the answer is no. That's not an adjustment which is available. Reducing tyre diameter would be the easiest way out of this one.

Thanks, that's what I wanted to know. Well put.

I'll try 25mm tyres

 

[fair weather cyclist]

So, I swapped the humongous 28mm giant gavia for a pair of 25mm hutchinson fusion 5 tubeless and the difference is immense, like day and night. There's a TON of clearance now.

 

[mpemburn]

Looks like you need deeper calipers, like the kind that are designed to accept mudguards. I have a pair of old Ultegras that were from my Trek Pilot. You're welcome to them if you want. Silver finish and not black, though.

 

[Sharky]

Came across this bodge on a Google search. May work.

"I've done this to improve fork clearance for street use on my track bike. You won't find a spacer or any kind, and cannot use a flat strip formed into a U since you only want to fill the bottom, without narrowing the sides.

I did it as follows. I cut a few bits from a spoke, (you can also use a bearing ball) and used that as reinforcement (and as a gauge) then did the job with body filler. That was 40 years ago, and I still use that fork without having to do anything else."