Crank arm problems

[Ben M]

My crank arm (non crankset side) has come loose. I was cycling along (stood up in top gear) and then felt that my left cleat was loose or something. After half a mile of pedalling with one leg (uphill, I must be a god or something) I've had a look to discover that my crank arm is loose.

here are pictures of how much play we're talking about:
edit: it does't look like much, but it's about an inch at the pedal, which is an inch too much!

How do i resolve this? I know nothing about this part of the bike, is it just a case of tightening up the bolt head on the outside (last pic) until it is tight? I know that it's a pretty basic question, but I want to be sure before I go tinkering with tightening and untightening things and then it falling to pieces while I'm going down a hill!

Cheers

 

[Landslide]

Yes, you do need to tighten up the bolt. Should take an 8mm allen key.

Beware though - by riding on the crank whilst it was loose, you may have damaged the mating surfaces between the crank arm and the bottom bracket axle. Keep an eye on it, and if it keeps on coming loose, you'll probably need to replace the crank arm.

 

[Ben M]

Yes, you do need to tighten up the bolt. Should take an 8mm allen key.

Beware though - by riding on the crank whilst it was loose, you may have damaged the mating surfaces between the crank arm and the bottom bracket axle. Keep an eye on it, and if it keeps on coming loose, you'll probably need to replace the crank arm.

balls.

Well I'll get it replaced under warranty, it's only covered 270 miles.

 

[fossyant]

Correct - warranty..........

I don't like the look of the spline on pics 1 and 2........

 

[Ben M]

I've given it a quick tighten, and it's turning okay, so fingers crossed =