Hi
I've installed a new 6700 Ultegra triple crank on my bike a few weeks ago, everything went fine then after finishing my first long ride with it I saw the crank arm fixing bolt missing so I put a new one and when I was on the trainer it came off again.
Nothing else on the crankset or BB seems loose or have any funny play, I am aware that crank arm fixing bolts are suppose to be hand tightened.
What am I doing wrong........
Thanks

Are you talking about the plastic preload bolt? once the preload has been set, and the 2 pinch bolts done up, this bolt should stay in place, mine has done a few thousand Km since last refitted, and is still there. if you mean the pinch bolts, these do have a torque rating (12-14Nm). the specs with torque rating are here https://techdocs.shimano.com/media/te...9830750016.pdf