Hollowtech crank preload bolt - essential?

[Racing roadkill]

Was the little clip in correctly on the L/H crank?

Yes, it didn’t help either time.

 

[Milkfloat]

Trust me when I say they can. I’ve had a couple of ‘detachments’ they are as scary as hell when they happen.

One came loose on a friends bike, whilst out of saddle on a fairly steep hill. Totally knackered the crank and his ‘ball bearings’.

 

[Moodyman]

Well, I've decided for my own piece of mind to order a genuine Shimano replacement crankarm. I was never happy with the far eastern copy anyway.