Helderberg

My new bike has hydraulic disc brakes and they have a very slight drag. They have a spot that drags slightly and I wanted to know if, other than changing the rotor, I can do anything to adjust for it. I have loosened the caliper, applied the brake and retightened, pulled the pads and spring to be sure the spring is applying pressure but I think the rotor is the only way for me to have 100% freewheel. The rear wheel is not an issue just the front. I am an old rim brake guy so this is all new to me. Also, I am being very picky here as this is not a major rub just something I notice when the bike is on the stand and the wheel is moved very slowly.
Thanks in advance, Frank.

rhenning

Disc brakes do have a slight drag all the time. The same is true in automobiles. Not sure when slight becomes to much. Roger

Andrew R Stewart 

Disk pad rub is just like rim brake pad rub but less easy to deal with. Make sure the rim/disk is straight. Just like with rims some people are better at bending disks into best alignment. Disk calipers can be cocked WRT the disk. But most have some sort of caliper alignment ability, moving the caliper within the mounting bolts' slots as example (and some like Avids also have a ball and socket mounting washer system to allow radial alignment). Using the caliper mounting bolts and the slots they reside in also serves to best center the pads over the disk. But just like linear or canti rim brakes either pad's movement can be affected by grit or grime independent of the other pad's movement. because the pads move so much less then those of a rim brake these little things are of greater value, WRT pad rub. Removing the wheel and reinstalling can change the disk/pad spatial relationship. This is one reason why through axles with their greater ability to settle into the same position repeatedly are favored. Andy

jimc101

New bike, this should be something that is resolved pre-delivery. From the sound of what you're saying, it's a slight warp int he rotor, not unusual, and you may find that a new one has similar issues, you can get rotor alignment tools from Park and others to bend them into alignment.

Bit confused about the 'spring' you mention, as there are no springs in Hydraulic or mechanical disc brakes systems, in Hydraulic, the pistons are controlled/pushed by hydraulic fluid (DOT 5.1 for Avid, mineral oil, Shimano, Magura and most others), for mechanical, the pistons are normally pushed in/manually adjusted by rotating using hex screws.

DrIsotope

A hydraulic or mechanical disc brake on a bicycle, when properly set up, has zero contact between the rotor and the brake pads unless the lever is pressed.

To the OP, you can just true the rotor. I give mine a needed tweak now and again with a crescent wrench. It's not difficult.

Helderberg

Thank you all for the responses. It is a very miniscule rub so I believe I will leave it alone unless it gets worse. As far as the "spring" I mentioned, it is a double fork looking piece that has two legs that ride on the plates that the pads surface is bonded too. It is used, from what I can tell by it's position in the caliper, to help the pads retreat after application. The temp of the brake fluid is also low as it is cold here so that might be a contributing factor to the issue.
Thanks again for the information, Frank.

fietsbob

Very basic ..loosen mounting bolts hold brake on while you retighten those bolts..

delbiker1 

This morning at end of OC, MD boardwalk.

I have a 2006 bike with disc brakes, my first. I still have the original rotors and pads from when is was new. I have other bikes, so, it does not get a huge amount of miles every year. I usually have to take the bike off the work stand to insure the wheels are remounted in proper alignment. My front wheel brake does have a bit of a squeal when it is on the stand, especially if the wheel is turned either way and when it spins at low speed. I stopped worrying about that as long as it rides true. I have been riding this bike a lot for the past couple of months as I mounted racks, bags, lights, etc. to make it a commuter/errands bike. I am going to replace at least the pads, probably the rotors also, but I want to get through the winter months first.

Leisesturm

Is that really a spring or is that simply the mounting clip that secures the pad in its holder? If you can tolerate the minuscule (gotta love spell check) rub you will probably find that it goes away as the pads wear, or as they bed into place.

Helderberg

I had done this and it did make it much better. I made this post to see if there was something more I could do but I do not feel the rub is anywhere enough to have me try out my non-existent rotor skills.

Thank you, Frank.

Helderberg

Thank you for this. I was thinking along these lines but being new to discs I thought I would ask.
Thanks you, Frank.

Helderberg

Nice looking rig and thanks for the response.
Frank.

dsbrantjr

If you want to try and get rid of that slight rub you might try rotating the wheel to the middle of the area where the rotor rubs before doing the loosen/brake/tighten routine. Or the rotor may need a tweak with an adjustable wrench as advised above.

Cyclist0108

Before you try bending the rotor, make sure the wheel is seated in the dropouts properly, and make sure the caliper is PERFECTLY aligned. I do this by taking the pads out, and looking to see gaps between the caliper and the rotor on both sides. If the caliper itself scrapes the rotor, it is badly out of alignment. Don't squeeze the brake levers while the pads are removed. Also, sometimes you have to reset the pads by prying them apart slightly, if no amount of manual alignment works.

Properly adjusted, they should be dead silent and not rubbing anywhere.

Helderberg

Thank you. I will try this and see what I find.
Frank.

Bigbus

You might also find a tiny allen head set screw on the caliper that when loosened allows you to use a larger allen wrench in the side that when screwed in or out moves the pad on the inner side (wheel side) in and out of the caliper housing for fine tuning. Mine was set too far out from the factory and the rotor rubbed it slightly until I adjusted it properly and then did the hold the brake lever thingy.

TimothyH

Ride it.

It will go away.


-Tim-

Helderberg

Final report. I put a few more miles on the bike and then readjusted the caliper with it hanging on the spot it was rubbing and then rode it some more. It is perfect now so all is good.
Thanks again for all the good information, Frank.

jadocs

Make sure your thru axles are torqued correctly. Then check to see if there is a perceptible wobble with the disc using a light in relation to your pads. Next do the loosening of your caliper trick where you loosen it, spin the wheel then apply the brakes while tightening the caliper back up. If it still rubs on one side you may need to clean the pistons because one may be actuating more than it should or the other is just sticking. Park tool has a good video on cleaning and "working" the pistons to get them to actuate properly again. After cleaning the pistons and "working" them to ensure proper actuation, press the pistons in on both sides all the way, remount the wheel, torque the axle properly, spin the wheel and apply the brake. If that doesn't fix it you either need to straighten or replace your rotor because it's bent, or there is something going on with your wheel.

Edit: disregard since you appeared to have it fixed.

Carverbiker