What size allen key fits the crank?

[night cycler]

I was on the canal recently, and coming towards me was a bloke pushing his bike. On enquiring what the problem was, he explained that the crank had come loose. I only carry Allen keys that fit things on my bike, and they are small sizes.

It kind of dissapointed me that I was unable to help due to the absence of a specific size key. I have plenty of keys at home, and for how little they weigh it won't matter to carry 2 or 3 larger sizes. So, can anyone tell me what size(s) I need to carry for cycle cranks. For so little effort on my part It can potentially save someone a long walk. I cycle that route two or three times per week.

 

[dan_bo]

Usually 8mm.

 

[MontyVeda]

8mm i think?

 

[ebikeerwidnes]

I had to get a set with an adapter to make the 6mm into 8 mm - the 8mm don;t appear on standard sets of keys
but if you look on the cycle tool websites you can find them with the adapter

 

[I like Skol]

Just checked and it is 8mm, but TBH it is a lump of steel to be carrying around just on the off chance you can help someone out of trouble. Also, if they have got to the point of a square taper crank arm dropping off the taper is likely wrecked and the same thing will happen again within a short time. They will probably get home I guess.

 

[fossyant]

It also depends - if square taper you need a socket, then another size allen key for GXP BB's - and it needs to be a big allen key with leverage.

So, not worth carrying that for someone else.

 

[night cycler]

Thanks for the advice.

 

[Sharky]

I've mentioned before, that you can double up Allen keys. Eg you can use a 5mm with a 3mm or two 4mm ones to make up the 8mm needed.

Not ideal, but should do enough to get you home.

 

[presta]

8mm for square taper, 10mm for Octalink.

 

[I like Skol]

8mm for square taper, 10mm for Octalink.

Like I said, pointless carrying stuff just to fix other people's bikes on the off chance, you'd end up carrying a full Park Tool workshop to cover all the possible variations! I do carry some small items not specifically for my bike but it is tiny stuff, like chain quick links for 9/10/11spd, after that they are on their own. These failures don't often happen without warning and the random catastrophic failure that wasn't foreseeable is usually unfixable.

 

[Cycleops]

You need to carry one these @night cycler. Invaluable. Plus it'll make you look like a hero to any stranded cyclist.

 

[MontyVeda]

8mm for square taper, 10mm for Octalink.

and 8mm on my isis cranks

 

[FishFright]

You need to carry one these @night cycler. Invaluable. Plus it'll make you look like a hero to any stranded cyclist.

I got one of those last year and luckily I've not had to use while out yet but it seems a quality bit of kit.

 

[shimceltic]

Similar theme but I'm replacing crank with power meter crank and it says tighten to 54nm. My tool doesn't go that high. Can I just tighten till tight and then give an extra nip?

 

[MontyVeda]

Similar theme but I'm replacing crank with power meter crank and it says tighten to 54nm. My tool doesn't go that high. Can I just tighten till tight and then give an extra nip?

probably. One doesn't really need a torque wrench if they've got some common sense