Author Topic: Alloy expander bolt in Cinelli stem  (Read 414 times)

Alloy expander bolt in Cinelli stem
« on: September 18, 2019, 10:48:27 pm »
1A stem of unknown vintage but 26.4mm clamp, so pre-mid 90s. Has the alloy expander bolt and wedge.  Is it safe?  It doesn't look damaged, the hex head is undistorted and the threads are excellent.  I don't think it's been overtightened.  Does anyone know the correct torque? I'd guess less than 5Nm.

Should I improve the odds by polishing it or (a tip I've read elsewhere) "setting" the wedge with a steel expander, if I can find one to fit, then replacing with the alloy bolt?
Never tell me the odds.

Re: Alloy expander bolt in Cinelli stem
« Reply #1 on: September 19, 2019, 12:50:15 am »
IIRC these bolts are aftermarket ones, I forget who made them, but they may have been anodised?  In which case no, you shouldn't polish it.

Is it safe? Probably; after all the stem will have a conical wedge and this usually jams itself pretty well.  Probably you could tighten the bolt and then back it off to a lower torque without the wedge working loose. However the bolt will see fatigue loads if the stem is a loose fit in the steerer. Belt and braces suggests winding a few turns of PTFE tape onto the stem before lowering it into position. If you apply it in the right way, the turns form a kind of wedge which helps stabilise the stem and helps deter moisture ingress too.

cheers

Re: Alloy expander bolt in Cinelli stem
« Reply #2 on: September 19, 2019, 08:42:59 pm »
I think only the 1R had the alloy expander bolt.

Someone might have taken one from a 1R and put it in the 1A.

Re: Alloy expander bolt in Cinelli stem
« Reply #3 on: September 21, 2019, 07:44:11 pm »
1A stem of unknown vintage but 26.4mm clamp, so pre-mid 90s. Has the alloy expander bolt and wedge.  Is it safe?  It doesn't look damaged, the hex head is undistorted and the threads are excellent.  I don't think it's been overtightened.  Does anyone know the correct torque? I'd guess less than 5Nm.

Should I improve the odds by polishing it or (a tip I've read elsewhere) "setting" the wedge with a steel expander, if I can find one to fit, then replacing with the alloy bolt?

Is it a wedge or a cone at the base of the stem?

Re: Alloy expander bolt in Cinelli stem
« Reply #4 on: September 21, 2019, 08:50:31 pm »
Most people over-tighten quill stems.  Tightened, you should still be able to move them with moderate force.

Re: Alloy expander bolt in Cinelli stem
« Reply #5 on: September 21, 2019, 09:04:30 pm »
1A stem of unknown vintage but 26.4mm clamp, so pre-mid 90s. Has the alloy expander bolt and wedge.  Is it safe?  It doesn't look damaged, the hex head is undistorted and the threads are excellent.  I don't think it's been overtightened.  Does anyone know the correct torque? I'd guess less than 5Nm.

Should I improve the odds by polishing it or (a tip I've read elsewhere) "setting" the wedge with a steel expander, if I can find one to fit, then replacing with the alloy bolt?

Is it a wedge or a cone at the base of the stem?
Cone, as usual with Cinelli (except their steel stems)
Never tell me the odds.