Sy Reene

Hopefully an easy question.. Is the overall clearance/distance that the brake arms open up after using the release, relative to how close together they are when they're not released? Or put another way, no matter how close or far you have the brakes set for normal operation, do they always open to the same width after release?

dsbrantjr

The way most brake quick releases work is to open a fixed amount beyond where the brakes are adjusted, by paying out a fixed amount of cable, set by their construction. A quick look at a photo will show how this is so.

Marcus_Ti

IIRC, using the center-adjust bolt changes the pad-to-pad clearance at least when closed. Might impact when open, but I never checked.

I suppose if you really have the barrel adjuster turned you can appreciably effect the open pad-to-pad distance

Sy Reene

So, another rephrasing: I have 21mm rims with 26mm (measured) tires (5mm differential). Using the brake release, it's quite difficult to get the wheel off the bike without releasing some air from the tires.

If I put eg. 24mm rims (3mm wider) on the bike and tires now inflate to 27mm (measured) or now only a 3mm differential, will it be any easier to get the wheels off the bike with inflated tires?

dsbrantjr

Assuming you adjust the brake pads to an identical distance from the brake tracks in both instances, you should have nominally 2mm more room. If you need more clearance to remove your tires you could do your initial adjustment with the brake barrel adjusters almost all of the way out, and run them in to open the brakes further, or add an inline brake adjuster and use both the adjuster and quick release when you need to remove/install a wheel: https://neweracycle.com/shimano-sm-c...able-adjuster/

Sy Reene

Thank you! Though I assume there's some sort of maximum capacity (width) of course and can't stay a relative relationship indefinitely?

dsbrantjr

Your brakes will hit some kind of internal stop eventually. Release the wire and you will see the limit.

Drew Eckhardt 

Yes, although you could just adjust your brakes instead of buying new wheels.

I avoid problems by setting clearance with the releases open so a fully inflated tire just fits with a little encouragement.

With 2010 Ultrashift levers and 2006 non-skeleton differential brakes my levers are still far enough from the bar they can't bottom with 25mm GP4000s on traditional 21mm (external) wide rims.

I did the same with 27mm Vitoria Mastercross tires for winter riding when I ran 1996 8 speed pointy hood levers.