[Tuesday]
Yet another test of my noisy singlespeed bike... Once again, it seemed ok for a short while but then the damn noise returned.
I was beginning to suspect that one or both square taper cranks were damaged due to riding with the retaining bolts not tight enough. I got a bit paranoid about
OVERtightening crank bolts after cracking this crank a few years ago...
I reckon I went too far the other way after that though, and haven't been doing crank bolts up tight enough. I read the other day that they need to be "
tighter than you would think". I checked and the RH one was not tight at all and that was despite having tightened it '
somewhat' the day before...
So, my next step was to swap the RH crank for the one from my turbo trainer bike. While I was at it I cleaned and lubed the chainring bolts. I did them up nice and tight, having got rid of any dry metal to metal contact points...
Another test ride... Ooh, that was sounding a
LOT more promising!
I thought that I had cracked it but I started to notice a much more subtle creaking noise. It turned out that it was a secondary creak from the saddle area. I had previously discounted the saddle/seatpost as noise sources because the main creaking noise had continued when I was out of the saddle. Now, all creaking noise went away when I stood out of the saddle.
SO... main noise problem solved, some saddle noise to deal with.
I stopped mid-test-ride and tried to tighten the clamp bolts -
they creaked! The threads were a bit corroded so the bolts were reluctant to tighten. I waited until I got home, loosened the bolts, lubed the threads, left them for 15 minutes, then did them up again. This time I could tighten them properly without any creaking noises as I did so. I also lubed where the rails were clamped. I'll do another test ride... I am feeling optimistic now!
[Time passes...
SLOWLY!]
Another test ride done. SUCCESS!!
I took a look at the square taper hole in the discarded crank. I am sure that it is no longer square! I took a photo of it and have drawn a rectangular border round the hole to compare the edges of the hole to. (The camera wasn't directly above the hole so it appears to taper bottom to top, but ignore that. The important thing to note is the the corners look like they have widened due to movements of the crank.)
(I know that looks like a childbirth photo, but the red colour is actually grease, and the weird dark crinkled bit in the centre is the surface of the glass kitchen chopping board that it is sitting on!
)
Riding with the bolt not tightened properly obviously allowed the crank to squirm slightly and widen the hole. Those movements created the creaking noise. As the hole got looser, the crank got to a critical degree of wear, and that happened halfway through my recent Garforth imperial century ride. The noise was rapidly getting worse and I feared that something was about to break. I think that the crank
would have broken eventually if I had just ignored the noise and carried on riding the bike over the next few weeks.
In the course of all of this, I have replaced the bottom bracket, the chain, the sprocket, and the crank. The crank was the only thing that really needed doing but it won't hurt having a newer sprocket on - the old one was getting pretty worn anyway. The old bottom bracket and chain probably still have a lot of useful life in them, so I will add them to my stock of half-worn spares!
I'll put the worn crank on the turbo trainer bike. I don't use it much and always have loud music on when I do, so I won't hear any creaks! I never get out of the saddle on the TT, so if the crank suddenly fails I shouldn't get hurt.
[Wednesday]
Another quick test ride...
Primary creaking noise problem (worn RH crank): FIXED!
Secondary creaking noise problem (corroded saddle clamp bolts/loose clamp): FIXED!
Now that the bike is almost silent, I can hear that there is a very minor click/creak every now and then. It may well be that the LH crank is damaged in the same way that the RH one was. I don't have a matching crank, but I do have one which would do the job if necessary. I'll see how it goes. If the subtle noise gets worse, or continues to annoy me then I'll do the swap. For now, I've had enough of messing about with the bike when I would rather be riding it!
)
