picked this Trek up off the side of the road and not sure what happened here? did the bottom bracket come unthreaded or was it too wide?
by Next-Shirt1455
picked this Trek up off the side of the road and not sure what happened here? did the bottom bracket come unthreaded or was it too wide?
by Next-Shirt1455
5 Comments
Bb unthreaded. Bearings likely seized to the spindle. Pedalling forward loosens a bb.
On BSA bottom brackets they thread in from the drive side, and this adjustable cup threads in from the non-drive side to tune bearing preload and compensate for any manufacturing tolerances.
You shouldn’t ride this bike like this – the BB likely will have a lot of play. You can use an Allen key and crack puller to remove the crank arm, and then a splined BB tool to tighten this back up. If you don’t have these tools, take it to your LBS and they will likely be able to fix it for you for pretty cheap.
So you stole it?
The nondrive cup is not threaded into the frame.
BB Cups usually have a lockring on the NDS side – either the person rebuilding the bike forgot the lockring, or it isn’t a cup-& spindle BB, but a BB Unit (Shimano BB-ES500 BB units have aluminum inserts but have a lip on the edge of the insert, so it is some cheaper BB unit like VP or similar).
Here, you can see the lipless NDS side (left) and the lipped DS (Right).
https://www.vpcomponents.com/data-99399
The BB unit’s NDS retaining insert has backed out, which is why it is sloppy but still works – the BB unit’s bearings are still (seemingly) okay.
Remove the left crank arm, get a shimano BB tool and remove the insert, verifying it s a BB unit and not a loose-ball & spindle arrangement.
if it is a BB unit, tighten it back in with a bit of grease inside and outside to seat & torque it properly, and it will not come loose again unless it has been damaged already (destroyed bearings, egged, wallered, worn, etc). If it were mine, I would take it apart, fully, pop the seals off the BBUnit’s sealed bearings, clean and regrease them, and then reassemble everything greased and torqued up to go test it properly.
The whole bike probably needs that, from the pedals to the hubs to the headset as well. It needs new grease everywhere, otherwise everything will grenade itself into garbage. something immaculately stored 10 years ago now has glue for grease that will mutilate every single moving part – and I bet that was not in immaculate condition when it was set aside and eventually thrown away.