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Just fitted a rear brake, wondering how close it should be to rotor?

2K views 6 replies 5 participants last post by  sslos 
#1 ·
Hi all,

I'm building a bike at the moment, with a mix of old components from my old bike (frame is crushed, but components are ok). I bought a new frame (On one inbred 29er).

My bike building experience is very limited, so figured about time i learn!

So far, i've fitted the rotors, front brakes,rims/tyres suspension fitted and cut down and steerer fitted. Handlebars on.

Which got me to the back brake, it sits really tight to the rotor, looks about 1mm gap. Is this normal? or can i buy another adapter that wont place the caliper so close.
See pic.
Bicycle tire Bicycle wheel rim Bicycle part Bicycle accessory Rim


Any advice, most welcome!
:)
 
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#2 ·
Are you saying the distance between the pads is 1mm or the distance between the top of the rotor and the body of the caliper is 1mm. If your pads seem too close take the caliper off the bike and the pads out of the caliper and press the pistons back into the caliper body. *be gentle and don't fubar the caliper face... the round end of a really small wrench works great* then reinstall the pads and caliper on the bike and center over the rotor and see if that gives you a shade more pad clearance.
 
#4 ·
I call the method of adjustment you used the "quick adjustment" for brakes. The best way to get your brakes correctly adjusted is to look through the rear of the caliper and make sure there's equal daylight on either side of the rotor between the rotor surface and the pad surface.

It's a little difficult to get it right on the first try though because your caliber bolts and the cup washers have high and low spots where they want to sit when you tighten the caliper. Just keep trying it until you can get it just right.

Edit: And to your question regarding the outer diameter of the rotor and its clearance from the caliper, this is solved by mating the correct size adapter with the correct sized rotor. A 160mm rear rotor needs a 160mm mounting adapter for the caliper. Make sense?
 
#5 ·
Clearance can be tight but as long as there is no contact I wouldn't worry about it. Neither component moves around in use. Make sure the wheel is seated properly in the drops - don't know how many times I've re-adjusted something, then when I put weight on the wheel it drops into place and have to start all over.
You can push the caliper over slightly during adjustment to get more clearance from the pad - see the Park instructions.
Park Tool Co. » ParkTool Blog » Shimano® Hydraulic Brake Service and Adjustment
Park Tool Co. » ParkTool Blog » Hayes® Hydraulic Brake Service
 
#7 ·
As long as you have enough clearance, you're fine.

Your rotor may be a bit warped, which happens. Try and minimize drag for the majority of the rotation, and if it's just kissing the pads in one area of the rotor, that's o.k.

As kerch13 said, this is a quick adjustment, and you're better off actually looking for equal gaps. I like to use a piece of paper behind the caliper to give me a light background for this.

Los
 
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