105 crank bolt

[Dave W]

http://www.cyclesportsuk.co.uk/product_ ... s_id=12702

What is the purpose of this? My mate has a new bike supplied without one. He's got to wait two weeks for another
I can't see a problem riding without it for now - what are your views?

[johntea]

It's used to tension the crank into the bottom bracket

[531colin]

That harmless looking cap thing actually sets the bearing pre-load. Park tools website...http://www.parktool.com/blog/repair-help/external-bearing-crank-systems-hollowtech-ii-megaexo-giga-x-pipe-x-type-campagnolo-ultra-torque...carries a pretty poor description, I would set any bearing pre-load by critically establishing the minimum tension to remove float.
Setting the bearing pre-load wrong will cause premature bearing failure, which external BB bearings are known for....how confident are you that this bike is correctly assembled, or that you can adjust the bearing correctly? (actually, you can't adjust the bearing at all, without that cap.)
I think there is a good case to reject this bike as not being of "merchantable quality" ....you want your money back, so you can buy a bike from somebody who knows what they are doing.

[cycleruk]

As other posters say - needed to set pre-load on crank bearings but not needed after the 2 small crank bolts are tightened.
Shimano supply a tool to tighten this "bolt" :-
http://www.amazon.co.uk/dp/B007VBV604/r ... wo=&hvqmt=

And is for finger tight only!