Q: I recently purchased a new “modern” bicycle with disc brakes and fancy electronic shifting. My problem is that I feel it is finicky and the bike always seems to be making noise. Maybe the rotor is pinging the brake pad or some other noise that comes and goes. My local mechanic told me that a lot of what I hear is beyond repair. Is he right, and am I expecting too much to drive safely?

A: Congratulations on your new bike. That being said, it seems the experience was less than ideal. I’m not sure what bike you’re coming from, but many modern bikes do have a certain level of noise that is hard to eliminate. This is, in my opinion, for two different reasons.

The first is mass production. Most modern bikes are mass produced and there is always an “acceptable” tolerance when molding or welding the frame. This can result in brake mounts that are not perfectly parallel to the axle or round holes that are not perfectly round. The worst thing is when things are slightly out of line, like the left and right bottom brackets. If they are not perfectly aligned or one is slightly elongated, then there is almost no long-term fix that a mechanic can do to fix it.

That’s changing as manufacturers go back to threaded bottom brackets or at least a single shell to minimize the chance of misalignment. This can add a bit of weight, but companies understand that it’s worth it to the end user.

The next challenge is that tolerances are getting tighter and accuracy is key. If we look back, we used to have five to eight cogs in the same space that we now have 12 and 13. The space between each cog on the cassette gets so close that if things bend too much or the alignment switch is off slightly, all the system is affected. Performance and speed of our systems are prioritized over durability. This does not mean that the current system cannot continue; it just means that if something is bent or misused, it will be obvious right away. There is not much room for disagreement anymore.

Disc brakes are the same. In modern hydraulic systems, there is no way to change the distance between the pad and the rotor. If there’s something wrong with the system, you’ll hear it. Sometimes things will line up perfectly, but the piston is slow to return, or the pad doesn’t always return, and you’ll get a little noise. This most often occurs after very heavy braking and heat build-up.

I was recently helping a friend work on their bike and they had SRAM rotors with a Shimano brake system. The rear seemed to work fine, but the front kept rubbing. There was no level of adjustment we could do to make it work. I measured the thickness of the SRAM rotor compared to the thickness of the new Shimano rotor and it was 0.18mm thicker. We put in a Shimano rotor and all the problems went away. It’s hard to imagine how small the difference is, but when the new rotor was on the bike and between the pads, we had some clearance on each side.

I don’t think you’re asking too much for a quiet bike. At the same time, there are so many factors that your particular combination may be the best. It’s not always more money and better parts, sometimes it’s just the luck of the draw. I had a bike that seemed beyond repair, then I just changed a few parts and it never happened again. A good shop should be able to target a specific area of ​​noise and offer at least a few options. In my experience, lack of maintenance, a dry chain, or completely worn parts is the number one problem.

Number two is over-maintenance of the bike. Yes, all too often I see people cleaning their bike so often and using so much cleaner all the time that they remove grease from key areas that normally don’t need maintenance.

Finally, I would take your bike to a few other mechanics and get a few more opinions. At the same time, don’t be surprised if the main reason is a discrepancy between the framework and the component. Pressed-on bottom brackets without an inner shell are notoriously bad, and improperly lined brake mounts are another cause of noise. Good luck.