Out riding this weekend and at the end of a long ride my cranks felt wonky.

CRANKS Suntour XCC-T208 Alloy, 28/38/48t

They’re running square taper.

They lasted about 4 miles after torquing the nds bolt to 50+nm. Then wonky again.
Then did them up to 70-80nm roughly, 5 miles it’s hanging off.

I’m tempted to just throw a spare GXP set on, I won’t be using it outside again. Will only survive on Zwift now.
But if I can sort the sunrace set I may as well.

Ideas?

can it be saved?

No

Wot he said

Never managed to save square taper that have come loose during riding. Always seemed to be non drive side for me, cheap to to replace if available.

For me square taper had 3 states.
1. Coming loose
Or
2. Creaking
Or
3. Siezed on

what have you buggered up. They never come loose. Three on my bikes have them and three family bikes too.

Not touched it since I bought the bike new. It’s done 2900km on Zwift and until the other day had been outside twice.

TBH, it’s not just square tapers, any type of crank that comes loose quickly gets a bit of deformation, then never stays tight again.

Yeah, it’s probably been loose and actually working it unevenly has finally killed it.

Take solace in the fact it lasted 2899.99km longer than the FSA Powerpro’s I fitted back in the day.

Aluminium pop can, cut a bit out without slicing your fingers off to make a shim, wrap it round the BB axle and smash the crank back on…worked for us skint teens back in the 90’s 😉

Recently used a can shim on my winter bike.

I had to keep tightening the cranks regularly, every half hour or so for the first couple of rides, then before each ride.  Now just checking ocassionally.

Square taper has its issues,  but holds up to the winter slop so much better than external BBs.

Sometimes the square is a bit bigger than spec so the crank slides too far down the taper. 2 possible remedies: either grind a bit off the end of the axle if it is protruding or grind a bit off the back of the crank if it is bottoming out.
Edit: Or a coke-can shim.

Or I’ll just throw it in the bin.

Thanks all. I came back yesterday and went to remove the square taper…. oh my…. both the driveside crank are was exceptionally tight…. but the BB itself, well that was just ridiculous, i needed a 24″ breaker bar on it in the end !! Eventually i got it out on both sides.

I then went to fit the GXPs, which the cranks went on great, but the chainring isn’t compatible… bummer… 2 of the sides will/would need a little trimming on the mount points.. I’d forgotten it was a thing, but it then came back to me.

So back into the spares box and found a Raceface shimano style crankset that the chainring fits… but not the BB, lol…. all my spare BBs are GXP, so had to scoot out and pick up a Shimano HT2 style BB yesterday and it’s now all back together and ready for Zwifting… I’ll need to think of a longer term plan if this bike ever goes outside again, but i’m not sure it ever will.

Thanks for the info though.

I loved square taper. BB’s lasted for years and never had an issue with cranks arms falling off. Maybe I just got lucky as I saw loads of cases where the non drive side had fallen off.