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I've a problem with my carbon road bars in the stem. each time I hit a pot hole, especially down hill the bars move in the stem clamp with a sharp crack sound. Ive bought a new torque wrench from topeak last week and some carbon grease to try to stop this annoying 'feature'
clearly the bars don't want to be over clamped so I followed the bars printed wrench settings using the wrench and added the grease. Last night I notices a small ridge has appeared close to the stem/bar area and kind of lost confidence in them.
Clearly I've not followed something right and i'm going to need a new set or Aluminum bars but has anyone else had a problem with getting the bars tight enough but not TOO tight?
what part were the wrench settings on - the stem i hope.
because theres no such thing as a clamping torque imafraid.
a clamping force depends on the tollerances , the surface area and the force applied via the bolt.
So handle bars cannot have a torque value on them - how does the manufacturer know what stem your using.
The stem can have one as the designer knows what his clamp area is , his tollerance and the bolt size - to give a safe grip pressure for a given torque.
IME if you torque up to the torque value given on ANY ritchey componant - it WILL slip regardless of fibre grip etc.
Onto another point - carbon bars are less tollerant of point loads from sharp edged stems - which sadly even from high end manufacturers still exist due to manufacturing processes.
I tend to take sharp edges off with a light file before fitting with fibre paste and trying at the suggested torque - if it doesnt work i up it by a couple ft lbs till it does stay solid. Remember engineering process and fear of lawsuits means theres always a safety factor.
*Never had a carbon related failure - and have 3 almost all carbon bikes in the house.
Hum, no numbers on the Carbon stem anywhere. Just a figure on the middle of the bars. Upping the bolt torque on the stem resulted in the bars still slipping so perhaps it's a lost leader. How carbon fails at such a critical part frightens me so I'll ride better with metal parts.
"How carbon fails at such a critical part frightens me so I'll ride better with metal parts."
badly designed anything will fail anywhere.
what brand are these componants. perhaps drop them a line and ask for advice.
Made by Ness and I got them from Planet x. I fear I may have answered my own question.