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Out on my Bombtrack Hook EXTC yesterday on a lovely gravel loop in East Dorset.
Bike is 6 weeks old, carbon, has a t47 bb. I waited for the 2020 model as the previous yrs models had a pressfit bb.
Yesterday’s ride was an experience of beautiful scenery, lovely gravel doubletrack and creaking bb.
Taking the chain off and rotating the bb it’s graunchy, clicky etc.
I’ve done 150km on it, over the last 6 weeks and exclusively in the dry so far.
Will pop it over to the bike shop later.
That's a bearing issue by the sounds of it. Some bearings can fail prematurely. It's not a fault if the bike (unless the shell has not been faced or the threads are misaligned) or the T47 "standard". It's either an unlucky bearing, poor installation or poor design of that particular bottom bracket that just happens to use T47
I'm not criticising the t47 std, I waited for this model yr so I could get the t47 instead of the 2019 model that was a pf30. I thought this one would be less hassle than the pf 30!Fingers crossed its just a dodgy bearing rather than a manufacturing tolerance issue.
I'm just worried that the alignment of the bb shell is out meaning the t47 can't be installed successfully. That'll mean a new frame I guess.
There seemed to be quite a lot of oil/ grease leaking out of the bb threads onto the shell and picking up dust in this dry weather. I can't recall seeing that on other bikes but it may be due to not getting this long a dry spell or the design of the bb shell (my other bikes are all steel and Shimano bb).
Decent bike shop can check and face the bottom bracket. Hopefully that should solve it.
Do you need to face a bb in a carbon frame?
You need to know if the faces are causing the misalignment.
On my carbon frames with threaded bottom brackets, the aluminium shell is just ever so slightly proud of the carbon.
From about 15:45 in
Making bottom bracket shells of carbon fibre frames to the required tolerances is quite difficult. It takes time , effort and money to get right.
Just google carbon fibre cfrp cure distortion, residual stresses, heat of cure, dimensional tolerances.
Got it back. Shop said bearings all good. Creak from dry joints on crankarmd Robb spindle and the self extracting holt was loose (not built up properly I guess?)
It’s a Bombtrack lyer crank and it seems a bit of a complex faff.
We’ll see how it goes.
I just got a Bombtrack Hook Ext-c and am having crank issues, 220km and the bb is noisy. It had tons of freeplay, I had to put 2 extra spacers in to 95% fix it (still creaks when standing) but I don't think having 6 spacers and a wave washer is acceptable on a brand new bike. Did any crank issue reoccur in last few months?
Just because T47 is "better" than pressfit doesn't mean manufacturers still won't cut corners on hidden components like BBs and wheel bearings etc to get the bike to a price point. Also check if the frame needs facing at the BB.
Apparently Bombtrack have said to the dealer just keep jamming spacers in till the play is gone, I don't think that's a solution (either does the dealer) and has me worried about Bombtrack's care for quality which at this point is nonexistent. I also have consistently loosening headset issues and some very poor cable routing in the frame.
Don't understand how this
Shop said bearings all good. Creak from dry joints on crankarmd Robb spindle and the self extracting holt was loose
Can be after this
Taking the chain off and rotating the bb it’s graunchy, clicky etc.
Can't see how the actions taken by the bike shop would remove any graunchy or rough feeling when spinning by hand with chain off.
I'd find a better bike shop, they sound like a bunch of monkeys.
Could be anyone of the following.
-Dirt ingress, bearings are contaminated and worn
-Worn through misaligment (frame is made in two halfs, they could be miles out, this may not be the case if the bb shell is of one piece construction)
-Poor quality, poor grease fill (or type)
Yet another way of mounting the cranks to the frame which yet again doesn't address the poor engineering/manufacturing at the centre, nothing wrong with 24mm axles and PF41/BSA threaded....
I also have consistently loosening headset issues and some very poor cable routing in the frame.
Did you grease the steerer tube? If so, clean it, dry joint will have less chance of slipping.
I'd suggest finding a good bike shop and having the bike inspected, checking the BB and headset for alignment is going to be tricky, so someone with a good eye is key. Whereabouts are you? Hopefully someone nearish will be able to recommend someone.
Just as an update the t47 bb is still going strong after the initial issue and despite wet rides and winters etc.
How was it fixed a year ago?
Glad it's worked out for you.