New Bike Brake Rub

[tomcat32]

I know this has been on here before but I’m still striking out. I am new to discs and the set up is driving me crazy. I got a new bike and it came equipped with Elixer 7’s (not my choice but it’s what came on from factory). The rear was rubbing out of the box. I loosened the caliper bolts and I can’t find an adjustment where it doesn’t rub. I took the pads off and attempted to push the caliper’s in with a tire lever. I didn’t notice any movement. The only lever I have is a Pedro’s Milk Lever which is very wide and doesn’t allow much wiggle room in there. I then pressed with a narrow screw driver. Do you have to put a lot of force on it to push it in?

Since the bike/ brakes are new would a few miles on the bike wear down the pad enough to eliminate the rub without premature wear on the pads and rotor or is this asking for trouble? I’d like to try to remedy this before I ride and prefer not to get charged $50 for an easy fix at a shop if can help it. Any further suggestions.

[Gdb49]

First, make sure your rotor is centered. If it is and you have compressed your pistons back in and it rubs again, check to see if your pistons are coming out evenly. If not, clean the pistons and lube them with the fluid used in your system- very careful not to let it get on anything else. Clean with rubbing alcohol. If this does not work, send it into sram. They make crappy brakes, but they are an excellent company that backs up their products. Plan B, buy Shimano brakes and be happy.

[Zeds Dead]

Is your Rotor true? Make sure your rotor isn’t slightly askew. Spin the tire and watch the rotor and see if it has any slight movement. When I installed my last pair of disk brakes it had a slight rub on the rear tire. When I spun the tire I could see it had a slight warp to the outer part of the wheel. So I took a long handles crew driver and rag to avoid scratching and just oh so slightly put a little pressure on it to bend it back in shape. Leave the rotor mounted to the wheel. This adjust can be made with it mounted to the bike.

I have read that when discs are sold from the factory that they are not always true and need to be calibrated upon installation.

[schwim ✓ supporter]

Hi there Tom,

You don’t describe the rubbing, but if it’s a constant light grab that centering the caliper doesn’t resolve(by loosening the caliper bolts, squeezing the lever and holding while tightening the bolts back up), I would suggest a light sanding of the pads on a flat surface with some fine grit (180 or up) sandpaper to gain you some clearance.

[tomcat32]

The rotors appear true and the rubbing is consistent the entire wheel revolution. How hard do I push in on the pistons to push them in? I also didn’t have great light when I tried that so I am going to try that again during daylight to see better. I was afraid to serious pressure on them and I couldn’t tell if they really moved.
I’ll go from there and try other suggestions . I’ll keep you posted.

[schwim ✓ supporter]

Is this a new bike, or a new-to-you bike? If it’s a brand new bike, there’s something wrong. If it’s new-to-you, it’s common for brake dust, dirt and other contaminant to build up on the piston. This doesn’t cause a problem until the pads are replaced and the piston needs to retract fully to fit the new fat pads. As was stated above already, you can take some q-tips with brake fluid and clean around the body of the piston so that it will slip fully into the caliper.

Once you’ve done that, take a tire spoon or something else like a flathead screwdriver and press the piston back into the caliper. Don’t force it, use a little pressure in the form of leverage from one side of the caliper then switch sides so you’re levering from the other side. Repeat. This will keep the piston from getting cockeyed in the caliper.

[tomcat32]

This is a New bike factory shipped.

[schwim ✓ supporter]

Well, you’re not dealing with contaminant on the piston then. I’ve had the exact same problem with Elixirs in the past. If the rotor is centered in the caliper(meaning it’s not rubbing on only one pad) then you’re going to want to sand down a little of the pads. I have seen people let a little fluid out of the system, but I strongly disagree as it makes for a spongy feeling lever when the pads begin to wear.

On my bike that has this issue, I replace one pad at a time because the caliper won’t allow two new pads without rubbing. I let them wear down some, stick a new pad on the outside, let them wear to the point that the inside needs replacing, then rinse and repeat.

For all brakes I’ve purchased since enjoying about 10 pairs of Elixirs I’ve made sure to buy another brand. I’ve dealt with squeals, vibration, introduction of air into the system, rubbing like yours, etc. The XT brakes can be gotten for comparable price and I’ve not had any issues with them to date.

[tomcat32]

I watched a few more videos and went back and took out the pads and tried pushing the pistons in with a little more force and voile, no more rub. Now onto derailleur adjustment. Thanks everyone for the input.

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