I was out riding with a pal, who is new to MTBing, when he stopped and shouted that his pedal had fallen off! On closer inspection the non driveside crank and had just dropped off!

The cranks in question are Truvativ Firex. Now I know they use a self extraction system on an inner and outer bolt. It appears that the inner bolt was no longer there. It must have fallen out or somesuch but I cannot figure out how this could happen. From what I can tell the inner bolt sits in the crank and the outer bolt tightens onto it. So when you tighten the inner bolt it pushes the crank arm onto the BB. How could the Bolt possible drop out??

So my pal needs to order a new bolt set. The inner bolt is an 8mm, does anyone know what size the outer is as it will need to be removed to re-fit the inner bolt!

I hope you can see what I am getting at….

Not sure i follow – if the outer bit is missing how did the crank fall off? The outer bit is just so you have something for the inner bolt to push against when taking the crank off.

The crank is held on by the inner bolt (8mm allen bolt). It needs a fair bit of torque – 40mn IIRC – so get a nice long allen key and go nuts. No need for the outer bit at all, till he wants to take ’em off

The outer bit is still in place, its the inner bolt thats missing!
just realised I said the outer bolt was missing in the original post! Now edited! Oops- – its still early in the morning…

Do you mean these?

no sorry is the GXP version so the external BB type of crank. I should just go away and start again shouldn’t I!

I’ve knackered two sets of Stylos in similar fashion, he’ll have sheared the bolt at the top of the thread and the head will have dropped out post. your mate may have damaged the threads on the axel too in which case they’ll be fubar also check the axel to see if the bolt is still in there (I’ve done that one too). Getting the retaining bolt out was a faff as well, I had to grind flat the head of an M10 bolt to make an ‘extraction tool’

get some shimanos on there would be my advice.

That sounds like whats happened here. Fortunately nothing appears to be left in the axel. He isnt into the idea of new cranks!