I’m wondering if you can help me identify a noise coming from my bike.
It seems to be most noticeable when the bike is on the turbo trainer indoors. What I’ve noticed is a knocking sound, which you can hear in the clip, that happens when I apply pressure to the handlebars. If I’m sitting upright, there’s no noise, but as soon as I lean forward and put weight on the bars, the noise begins.
Any ideas on what could be causing this?
This is the waveform for the sound file, showing in the first 10 seconds or so where I’m sat upright and spinning up the pedals. Then I lean forwards, drop a gear, and it begins.
This only seems to happen when I put weight on the right side of the bike. While I’m sitting in the saddle and leaning forward, if my weight is either distributed centrally or more to the right, especially on the right handlebar (whether in the middle or fully out on the drop), the noise occurs.
I’ve also noticed that this noise only happens on the downstroke of my right foot. It seems potentially related to the right pedal, as the noise occurs when the pedal is at the very bottom of the downstroke.
One thing to note is that I don’t think I’ve heard this noise outdoors, though I can’t guarantee that. Unfortunately, due to recent injuries, I won’t be able to head outdoors anytime soon to validate this.
Any thoughts or suggestions on what it might be and how to fix it would be very gratefully received.
These sorts of issues are often quite difficult to figure out (it’s worse on a tandem!). It could be that the noise is occurring when the effort is high, which would correspond to pulling on the bars. It could still be the BB bearings, or the pedal bearings, or even your rear quick release (or thru axle) not being tight enough on the trainer.
From the waveform, I’d say it’s a regular click, albeit with some clicks missing. How does “sample index” relate to sound? Looks to me like a click corresponding to a cadence of around 90-93 rpm. I’d check your pedals are smooth and tightly installed (maybe remove them, grease them and refit). Could be the bottom bracket bearings. Could be a loose chainring bolt.
Thanks for the suggestions. I’ll check what I can do myself, but a check by the mechanic probably wouldn’t do any harm either.
The wave form wasn’t generated by me – it was a happy accident of uploading the audio file into ChatGPT whilst trying to convert it from .m4a to .mp3, because my webserver wasn’t set up to allow uploading that format. I got round that in the end, but kept the wave form image for the post. Here’s what ChatGPT says on the sample index:
I didn’t notice the noise at all during yesterday’s ride. How odd. But it’s been happening off-and-on for a long time now.