Sergej

Thanks for all the answers.

Currently I'm fitting a Schwalbe CX comp 700c 30mm and it's absolutely spot on 0 clearance.

0 clearance on the seat tube and I had to sandpaper a little bit of the carbon break caliper that was slightly touching the tyre.

I still have some doubt about the brakes.

The bike is supposed to be 'light' (it weights 6.5kg).

Now I have these carbon brakes who perform just 'good enough' but in rain it's not the safest thing. But it's the lightest.

I can, maybe:

-Use an extension for my current caliper? I'v seen a metal plate to add between the brake and the frame. (not a lot o choice on wheelset 650b with rim brakes)
-Buy a new and heavy long reach brake but still not a lot o choice on wheelset 650b with rim brakes.
-Convert to disk brakes, adding weight but safety. I've seen some conversion kit, don't know whether they can work on my bike, especially if the disk+wheel fit into the frame.

Thanks, sorry I'm still thinking what would be a proper fitting.

Sergej