Originally Posted by lastplace
I've used mounting brackets like this in long rallies and the bolts sometimes get loose.
I went with smaller threads, to get more threads in the headstock tube and where possible I use CSK SHCS; countersunk socket head cap screws. Countersunk heads are self locking by nature and resist vibration and loosening to a far greater extent than flat head bolts. You will notice this is why they use countersunk nuts on touring cars (and maybe F1) cause they dont want the nut coming loose and the wheel falling off. It is obviously more of a PITA to drill AND countersink holes than just drilling a hole and putting a bolt in. However the reliability is greatly increased using countersunk heads. You just need to have the right tools used at the right speed to get a good countersink.
Secondly, to be sure, Loctite, the real strong kind cause once that block is on it aint coming off.