Q: I recently got a new “modern” bike with disc brakes and all the fancy electronic shifting. My problem is that I feel like it is finicky, and the bike always seems to be making some noise. Maybe a rotor pinging the brake pad or some other noise that comes and goes. My local mechanic has told me that much of what I am hearing is not fixable. Is he correct, and am I expecting too much to have a quiet ride?
A: Congratulations on getting a new bike. With that said, it sounds like the experience has been less than ideal. I’m not sure what bike you are coming from, but many modern bikes do have some level of hard-to-remedy noises. This, in my opinion, is 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 a frame. This can lead to brake mounts that are not perfectly parallel to the axle or round openings that are not perfectly round. The worst is when things are slightly out of alignment, like the left and right bottom bracket openings. If those are not perfectly aligned or one is slightly oblong, then there is almost no long-term fix a mechanic can make to correct it.
This is changing as manufacturers are going back to threaded bottom brackets, or at least a single shell to minimize the chances of misalignment. This might add a bit of weight, but companies are realizing it is worth it for the end user.
The next issue is that tolerances are getting smaller, and precision is key. If we look back, we once had five to eight cogs in the same amount of space we now have 12 and 13. The space between each gear on the cassette is getting so close that if things flex a bit too much or the alignment of the derailleur is off just slightly, the entire system is affected. The performance and speed of our systems are prioritized above durability. That doesn’t mean a modern system can’t last; it just means that if something gets bent or misused, it will be evident immediately. There is no longer as much room for variance.
Disc brakes are the same thing. On modern hydraulic systems, there is no way to alter the distance between the pad and the rotor. If there is anything in the system that is not perfect, then you will hear it. Sometimes everything will be perfectly aligned but the piston is slow to return, or the pad doesn’t always return and you will get a bit of noise. This happens most after very heavy braking and there is heat buildup.
Recently, I was helping a friend work on their bike, and they had SRAM rotors with a Shimano braking system. The rear seemed to work fine, but the front rubbed all the time. There was no level of adjustment we could do to get it to work. I measured the thickness of the SRAM rotor compared to the thickness of a new Shimano rotor, and it was 0.18mm thicker. We put the Shimano rotor on, and all the issues went away. It’s hard even to imagine how small that difference is, but when the new rotor was on the bike and between the pads, it left us with room to spare on each side.
I don’t think you are asking too much for a quiet bike. At the same time, there are so many factors at play that your specific combination might be as good as it gets. It’s not always more money and better parts, sometimes it’s just the luck of the draw. I had a bike that seemed to be unfixable, then I simply swapped a few parts out, and it never happened again. A good shop should be able to target the specific area that is leading to the noise and offer at least a few options. From my experience, lack of maintenance, dry chain or completely worn parts are the number-one issue.
Number two is over-maintaining your bike. Yes, I see it too often that people clean their bike so much and use so much cleaning product all the time that it removes the grease from key areas that are normally low maintenance.
At the end of the day, 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 root cause is in the variance between frame and component. Press-fit bottom brackets with no internal shell are notoriously bad with improperly faced brake mounts being another noise making culprit. Good luck.
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