Left hand crankset

[silence32]

Hi guys,

I'm after a bit of advice please. I have a Scott solace 20 2014, which I've had for about 18 months. Yesterday after 40 ish miles I start getting a creaking, grinding noise from the left had crank arm. After pulling over I noticed the Allen bolts where loose and managed to tighten them back up and all was good for 10 miles. Then it started again, the crank arm was loose. I managed to coast it back home as best I could but the arm just came off. The teeth on the arm just grinded away.

Will I be able to get away with just replacing the left arm? If not, will I be able to replace other parts without buying a new crankset?
Im in 2 minds whether to try and fix it by myself or just take it to a LBS. :-s

Thanks in advance

Scott

 

[ianrauk]

If you can find a single left hand crank arm that's the same, then yes it's just a straight swap.

 

[mjr]

Some local bikes shops seem to accumulate left-hand cranks in the remainders bin, as well as sell them new... but I admit that all of my bikes are square-taper, so I've not really looked whether there are fancy teethed ones in there.

 

[Yellow Saddle]

That crank is ruined. Shimano sells left cranks singly.

A note on nomenclature:

1) Left crank, right crank.
2) crankset for both.
3) Crank, not crank arm.

Your crank will have a Shimano code on it somewhere. It will be a FC-6080 or similar number after FC. Go to your bike shop and ask them to order a left crank with that code. Then, learn how to torque it properly. It has two pinch bolts which have to be torqued in a very specific way. It is important that they are torqued incrementally and equally up to 14NM otherwise you will have a repeat of the above problem.

 

[rusty bearing]

I notice the o.p says that the crank bolts were loose so he tightened them up, no mention of the preload cap. Is it missing or just not mentioned?
I presume from the fact that 'after 10 miles the arm fell off' its gone missing.

 

[Smokin Joe]

I'm generally in favour of technological improvements on bikes, they have progressed beyond all recognition in my time and are all the better for it.

But I think square taper was a far better system than any of it's modern counterparts. Thankfully, it is still available.

 

[Yellow Saddle]

I'm generally in favour of technological improvements on bikes, they have progressed beyond all recognition in my time and are all the better for it.

But I think square taper was a far better system than any of it's modern counterparts. Thankfully, it is still available.

I'm a fan of square taper but it has its problems too.

1) The bolt requires tightening to the limits of the bolt's strength. This is easily abused by ham-fisted mechanics.
2) It is heavy. In polite conversation I'll deny that I've ever said this because I'm not a weight weenie by any means.
3) The crank rides further up the taper with use, allowing the bolt to come loose.
4) It requires special tools.
5) It doesn't make much money for manufacturers and retailers.
6) It is mature technology and therefore by default, not good enough for pro wannabes.