On my pub bike, I have a square taper bottom bracket with a cheap old spech chainset, and the non-drive side arm keeps coming loose, like 3 times in about 6 miles last night. Pain in the ar$e really. I remember a thread about this a while ago but couldn't find it. Can't see any cracks in the arm, but the little rubber insert thing has seen better days. Any ideas?
Bike Forum
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crank arm falling off
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Posted 1 year ago #
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It was a crack when this happened to me. Screw it on really tight and if there are any cracks they should become obvious.
Posted 1 year ago # -
Buy a new one. Pauls Cycles sold me a sq. taper non-drive crank arm for the grand sum of £7 a couple of years back.
Posted 1 year ago # -
Once it's fallen off the taper is fubarred and you must replace it.
Posted 1 year ago # -
I could be wrong about this, but if you don't keep square taper cranks tightened then the NDS tends to round off until it starts constantly falling off.
At least mine did. The solution was some new cranks, though perhaps you can bodge some kind of shim in there?
I usually tighten them now with a great big long piece of steel pipe. 45Nm I read somewhere.
Posted 1 year ago # -
as above. Once it was loose and prior to it falling off you were riding it with play in the crank.
This play meant that the square in the crank was rounded off and hence can never be tightened up again.
I too have bought a cheap one as a replacement. Just ask at your LBS.
Posted 1 year ago # -
yup - the taper is shagged. new crank arm.
in fact I've got an old, non rounded one you can have if you like
Posted 1 year ago # -
great, new crank it is then.
jimbobrighton, sounds good, what colour, length etc?
Posted 1 year ago # -
Whilst the taper may be shagged when this happened to me I put the bolt on with lock-tite and tightened it hard and it was fine for another couple of years until I changed the chainset.
Posted 1 year ago # -
silver/shimano/cheap/came off my commuter/170mm/not very pretty/has been used for other purposes since coming off bike i.e. hammer/but the taper is fine!
Posted 1 year ago # -
hummm, black spech one side, silver shimano the other, sounds like a new niche!
Posted 1 year ago # -
hummm, black spech one side, silver shimano the other, sounds like a new niche!
You'll be ahead of the curve. The envy of all the local kids.
Posted 1 year ago # -
You'll be ahead of the curve. The envy of all the local kids.
looks like I NEED it then, Jimbobrighton yhm.
Posted 1 year ago # -
Could be more niche than you imagine if you don't check the orientation of the square(some look like a square, some look like a diamond.)Cranks out by 45 degrees anybody?
Posted 1 year ago # -
Piece of coke can cut as a shim......
Posted 1 year ago #
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