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@GreatSince78
Hi All, I recently built up and sold a Pearson Touché bike, everything seemed to go smoothly with the build but the seller has experienced some issues which I'm struggling to sort out.
Initially everything was fine with the bike, after a first 12 mile ride all was well, but a week later the buyer was riding when he heard what he describes as a loud cracking sound. I think he inspected everything at the time and all seemed ok so he continued to ride, but then when he got he home noticed the non drive side crank bolt had unscrewed itself and the crank was slightly lose.
That's when he first reported the problem, we couldn't explain how the crank bolt could have unwinded itself, so at a loss I thought maybe someone had tried to steal his cranks, unlikely as that seeemed. Anyway so we agreed he'd retighten the crank bolt and see how it went. However the following day during another ride he heard the same terrible cracking sound the left crank bolt had unscrewed itself slightly and the crank was a tiny bit lose. He retightened the bolt mid-journey but then later dropped the chain a couple of times, even though drive side crank stayed fully tightened.
Understandably frustrated we discussed the issues, I was at a total loss to what could be causing the problems, but thought it could be a dodgy thread on the non-drive side crank bolt or even the thread inside the bottom bracket spindle. I thought if this thread was somehow ruined it could explain the bolt slipping. This seemed unlikely as the bottom bracket was brand new but to be on the safe side I said I buy a new BB, fit it, and see if that sorted the problem.
We fitted the new BB on Monday, everything went smoothly and I took the opportunity to check everything else and all looked fine, but to my horror the buyer got in touch again today to say he heard the same cracking sound twice during a 5 mile ride! I'm completely baffled as to what the problem is, so does anyone have any suggestions please? I'm at my wits end!
The chainset itself is in good condition, there is a tiny amount of rounding on the non drive side spindle hole, which I assume happened when the crank came lose, but it's very marginal. The crank itself isn't cracked etc, the chainring is in good condition and chainring bolts properly tightened. Both the original and second BB are normal JIS square taper, and when fitted the cranks seem properly seated. The chainline is good, maybe not perfect but pretty close, and the frame itself is fine, no cracks or any other damage.
As the BB has been changed my only hunch that the problem is chainset related, so I'm going to switch the current Stronglight which came on a Pompino to a Stronglight 2000 track chainset. The chain is a new KMC S1 1/8 one, the fixed cog is an unbranded but almost new 18t one, so Indount they are the problem. Anyway any thoughts people, this problem is really doing my head in, and I feel bad for the buyer who has been very patient.
Thanks in advance....