Mountain bike pedal woes.

InertProtocol · 24 Jul 2013 at 12:38

Hi all,

Not my any means a biking expert but one of my pedals, the whole thing has come off.

The the pedal bit where you put your foot, but the 'arm' bit that screws onto the frame itself. What is it called?.

I don't know where the nut that holds it on has gone but i need to replace it.

Not knowing what size to go for, any suggestions?

Thanks

touch · 24 Jul 2013 at 12:44

The bit between the pedal and the frame is the crank.
There are a few different types, can you post a picture?

tom_e · 24 Jul 2013 at 12:44

Crank arm is what it's called can't help on the nuts and bolts though.

arknor · 24 Jul 2013 at 13:17

measure the width of the threads ? there's probably not that many sizes they come in so it's likely easy to determine even if your a few mm off

or just take the crank arm to your local LBS

InertProtocol · 24 Jul 2013 at 13:19

Ahh, thanks all! - Will take a picture tonight if i can't resolve.

It's the left crank, done a bit of digging and need to measure the length of the right one (complete novice as i said).

Appreciated folks :cool:

xMarkie · 24 Jul 2013 at 13:28

Diagram of a mountain bike chain wheel;

Supercow · 24 Jul 2013 at 16:01

Why does the crank need to come off?

Edit: never mind, seems I can't read

Nexus · 24 Jul 2013 at 18:44

Wait, the whole crank arm came off when you were riding?

Supercow · 24 Jul 2013 at 18:55

Nexus said:
Wait, the whole crank arm came off when you were riding?

Easy enough to do.

Nexus · 24 Jul 2013 at 18:57

Supercow said:
Easy enough to do.

Never seen that happen in all my years mountain biking and even working in a mountain bike resort!

I could see it perhaps if you bashed it really hard against a rock, but fundamentally it would have to be loose in the first place, otherwise it would just get bent out of shape.

Supercow · 24 Jul 2013 at 19:00

Being loose in the first places exactly what I'm referring to.
Not ever checking your bolts ( which is highly likely in this case) will eventually end up with it falling off

Jonny ///M · 24 Jul 2013 at 23:27

If it's came that loose it's fallen off then it's likely that the square of the crank has been rounded off.

New chainset can be had from suntour about £25-30 if that's the case.

If not then upgrade to a deore external cup chainset for around £60 I think which includes the BB.

If it's a cheap bike then try just getting a new bolt from a LBS and getting it as tight as it needs to be and go from there.

Edit: Not sure why I assumed drive side crank as it's 99% of the time the left hand crank. You could pick one of those up for less than a tenner if the square is rounded off.

Clint_001 · 27 Jul 2013 at 15:12

Happened to me a few weeks ago. The local bike shop gave me a replacement bolt free which was nice of them, however the crank arm was rounded and just come loose again as it won't sit on the taper properly.

+1 for upgrade, I changed to hallowtech II type crankset which is far far nicer.