blizzard wrote: I think my torque wrench calibration is out. Adjusting the angle of my carbon bars. Tightening the stem bolts, got all 4 to 3.5nm. Set the wrench to 4.2nm, tightening a little bit a heat a crack, suspiciously like CF cracking. Stopped tightening, bars look ok, no damage and tight. I put my full 74kg on the drops and lifted my feet off the ground and no cracks or deflection. Going to ride as is.
I have now bought a t-handle 4-6nm wrench until I get time to test and calibrate the click style wrench (it's a Giant 2-15nm if anyone is interested).
It's quite important that you tighten the handlebar clamp faceplate bolts correctly so as not to damage carbon bars.
Do them up in a diagonal pattern similar to tightening and torquing down engine head bolts.
Looking at the plate and 4 screws from the front of the bike number top left bolt as 1, top right as 2, bottom right as 3 and bottom left as 4.
Do each bolt up finger tight, then starting at bolt 1 give it a quarter turn. The next bolt is number 3 - quarter turn followed by bolt 2 - quarter turn and finally bolt 4 - quarter turn.
The order is 1-3-2-4.
Keep tightening each bolt in that order, incrementally, with the same amount of turn but from now on with only a very small but exactly the same amount of turn, say 1/8 or even 1/16 or less twist on the allen key. Finish off with a torque wrench.
The gap between the faceplate and the fixed part of the stem should be even, with the same width gap on top and below.
I wrecked a friend's cheap (and soft) handlebars doing things incorrectly leaving dents in the bars from the clamp and heard that same cracking noise although none of the bolts were over-torqued.
In a rush I didn't do the bolts up in small even increments nor in the proper sequential pattern.