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Oh the joy
I have a bike packing trip I leave for tomorrow. Following the shake down ride I discovered a knackered bottom bracket.
So last weekend I swapped the bottom bracket. Seemed a bit creeky on a easy group ride yesterday. I thought it was the pedals which I greased this morning. Final loaded ride today and it’s still creeking
I have the cranks off and tried tightening everything. Still creaking
Any comments on either of these thoughts
I’ve fitted a shimano un 300 for the first time. I knew it wouldn’t be durable but I thought it would work. It seems that as I tighten the non drive side cup something pinches and the spindle gets harder to turn. So that cup is tight but not mega tight. I’m using an 18 inch spanner. It’s a good firm push but not I could push a bit harder
Its a spa cycles chainset. Is the first time I’ve used a shimano bottom bracket. Is it possible that the square taper varies slightly between brands?
I’ll take an 8mm Allan key. I can cope with creaking I just don’t want it going wrong
I’m assuming you don’t own a torque wrench? It would be good to get your hands on one and check both the BB shells and the crank bolts are at the correct torque. Otherwise we’re all just guessing.
New crank bolts is also a reasonable idea.
And it still could be the pedals, got another pair to try?
I wouldn’t necessarily be expecting imminent failure.
Finally, I fitted (& torqued) a un300 a couple of weeks back, no creaks.
Use some plumbers PTFE tape around the threads rather than grease....
It's not pedals I can recreate the fault by putting the front wheel against a wall and pressing down on a pedal or crank
I've had the cup out again to check for over packing of grease. I then put it back in and gave it a good pull on the spanner. It's not as bad now but I can still see the spindle flex. However I'm less worried about failure
I might stop at St John Street cycles and buy a BB on the way down tomorow
Remove, clean all threads and refit. Had a UN300 on my commuter for a year, its been fine. The locking collar should tighten till around flush with the frame.
The spindle should spin freely.
I thin I've got it. I the non drive side cup wasn't that tight on the bearing. So I added a few turns of plumbers tape. So far no creak. Who know when I've actually been for a ride
I'm confused. This is a sealed cartidge bb, there is nothing loading the bearings that you can adjust is there?
No nothing to adjust
But the non drive side cup cartridge interface seemed slack to me
You have got the correct size haven't you? 68 Vs 73mm shell
How old is the BB?
I had a well used xt chainset, I swapped the bb and the pedals and it still creaked. On close inspection there was a small crack in corner of the square taper part of the crank.
It's not that likely but worth close look if chainset is older.
I think St John Street Cycles ceased to have a physical shop quite a few years back.
Or did they reopen? Good news if they did.
I’m confused. This is a sealed cartridge bb, there is nothing loading the bearings that you can adjust is there?
It's usually the bb interference with the frame threads, not the bearings. Plumbers PTFE tape fix (instead of grease) has been a LBS shop fix for a number of years.
Ok so lucky I’m not relying on visiting St John Street Cycles
I didn’t plumbers tape the threads as they seemed so tight already. But thanks for the help I think I might have got it
Ok so lucky I’m not relying on visiting St John Street Cycles
For clarity, as the previous happy owner of a Thorn bike, I contacted SJS as to whether they had a shop again, and they replied:
'Yes we have a shop Mon to Friday 8.00 to 4.20. However all stock is in the warehouse so it is not possible to browse products.'
So, same kind of set-up as Merlin in Chorley, effectively.