HOW TO FIX COMMON NEW BIKE NOISES

Q: I recently got a new “modern” bike with disc brakes and all the fancy electronic shifting. My issue is that I feel like it’s finicky and the bike always seems to be making noise. Maybe a rotor pinging the brake pad, or some other noise that comes and goes. My local mechanic has told me that a lot of what I’m hearing is beyond repair. Is he right and am I expecting too much to have a smooth ride?

A: Congratulations on the purchase of a new bike. That being said, it sounds like the experience was far from ideal. I’m not sure which bike you’re coming from, but many modern bikes have some level of hard-to-fix noise. I think there are two different reasons for this.

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 result in brake mounts that aren’t perfectly parallel to the axle or holes that aren’t perfectly round. The worst is when things are slightly misaligned, like the left and right bottom bracket holes. If these aren’t perfectly aligned, or one is a little long, there’s almost no long-term fix a mechanic can make to correct it.

This is changing as manufacturers resort to threaded bottom brackets, or at least a single cup, to minimize the chance of misalignment. This might add a bit of weight, but companies are realizing that it’s worth it for the end user.

The next problem is that tolerances are getting tighter and precision is key. Looking back, we used to have five to eight sprockets in the same space, now we have 12 and 13. The spacing between each cog on the cassette gets so tight that when things flex a little too much or the derailleur alignment is only slightly off, the entire system is affected. Performance and speed of our systems take precedence over longevity. That doesn’t mean a modern system can’t last; It just means that if something is bent or misused, it’s immediately obvious. There’s not that much room for variance anymore.

Disc brakes are the same. With modern hydraulic systems there is no way to change the distance between the brake pad and the rotor. If something is not perfect in the system, you will hear it. Sometimes everything is 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 usually happens after very hard braking and heat build-up.

Recently I was helping a friend work on his bike and he had SRAM rotors with a Shimano braking system. The rear seemed to work fine, but the front rubbed all the time. There wasn’t a level of customization we could do to get it working. I measured the thickness of the SRAM rotor versus the thickness of a new Shimano rotor and it was 0.18mm thicker. We tightened the Shimano rotor and all problems went away. It’s hard to imagine how small that difference is, but once the new rotor was on the bike and between the pads, it left us room on each side.

I don’t think you are asking too much for a quiet bike. At the same time, so many factors come into play that your specific combination could be as good as it can be. It’s not always about more money and better parts, sometimes it’s just the luck of the raffle. I had a bike that couldn’t seem to be fixed, then I just swapped out a few parts and it never happened again. A good store should be able to target the specific area leading up to the noise and offer at least some options. In my experience, lack of maintenance, a dry chain or completely worn out parts are the number one problem.

Number two is over-maintenance on your bike. Yes, I see it too often people cleaning their bikes so thoroughly and constantly using so much detergent that it removes the grease from key areas that are typically low maintenance.

At the end of the day I would take your bike to a few other mechanics and get a few more opinions. However, don’t be surprised if the cause lies in the mismatch between the frame and the component. Press-fit bottom brackets without an inner cup are notoriously bad, with misaligned brake mounts being another culprit for noise. Much luck.