I was recently adjusting my front derailleur height stupidly and when I was retensioning the clamp I wondered if there is a specific torque it needs to be at. I retensioned and heard no cracking in see no bending but I'm still worried. Thanks nick c
Cannondale system six front derailleur torque
nick134679
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I was recently adjusting my front derailleur height stupidly and when I was retensioning the clamp I wondered if there is a specific torque it needs to be at. I retensioned and heard no cracking in see no bending but I'm still worried. Thanks nick c
If you tightened it tight enough that it doesn't move, and not so tight that you broke anything, than it's OK and there's no need to worry. If it moves, it wasn't tight enough and you can reposition it and tighten it tighter next time.
You're tightening a mounting clamp on a bicycle, not an engine bolt on a rocket ship.
You're tightening a mounting clamp on a bicycle, not an engine bolt on a rocket ship.
I don't do carbon, but im pretty sure this is completely incorrect.
Check the manufacturer website for a manual or consult your LBS because carbon frames do have maximum torque figures. Just a few days ago there was a thread about someone cracking their seat tube by over torquing their FD clamp. A friend of mine owns a carbon repair business and he tells me about even shop mechanics accidentally cracking a carbon frame on occasion.
I think most people that home wrench on carbon frames invest in a torque wrench.
Edit: He was right, it is not a rocket ship.
The Op had already tightened his FD, and I wasn't suggesting that he tighten if more. In fact, quite the opposite, I suggest tightening FD's only enough to keep them in place. If the amount of torque to do that is too high, than we have an impossible situation whereby there's no way to securely mount the FD without damaging the frame.
Torque specs fro FD clamps are problematic because the proper torque varies with the FD clamp construction and fit. While there are folks who over-tighten without thinking, there are more who've damaged their frames by blindly following a torque spec without considering what they were doing. A misformed, or undersized clamp can easily crack a seat tube at well below the published torque spec, while a well fitted one won't at way above the torque spec.
Torque specs are fine as guidelines, but learning to mount hardware with an idea to what's actually needed, and an eye to what's happening will make you a far better mechanic than would ownership of a torque wrench. It isn't about the tools, it's about the knowhow.
I agree with everything you said in your second post. I also misunderstood the problem. Believe me, I have always been a home wrench (cause I am cheap) and almsot never have the 'correct' tool for the job (cause I am cheap
). Considering the damage done to some frames by over torque i thought your first post was far too general and didn't really provide good information. That being said, i think the issue was addressed, sorry for some of the misunderstanding.
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OP - whose FD are you using? Campy? Shimano? SRAM? Band adapter for a braze-on?
You do have a little bit more leeway in your clamping torque since the bike has an aluminum seat tube, but you're right to still exercise caution. Like FBinNY said, the minimum amount of torque that holds the FD in place is the correct amount. Still, here are the "brand manual" recommended values:
Again, those are from tech docs available on their respective websites and that would come in boxes with parts. If 4 N.m were enough to hold a derailleur in place, why go to 5? It is easier on the bolt, the derailleur clamp, and the seat tube...
You do have a little bit more leeway in your clamping torque since the bike has an aluminum seat tube, but you're right to still exercise caution. Like FBinNY said, the minimum amount of torque that holds the FD in place is the correct amount. Still, here are the "brand manual" recommended values:
- Campagnolo: 7 N.m
- Shimano: 5-7 N.m
- SRAM: 5-7 N.m
Again, those are from tech docs available on their respective websites and that would come in boxes with parts. If 4 N.m were enough to hold a derailleur in place, why go to 5? It is easier on the bolt, the derailleur clamp, and the seat tube...
NO NO NO !!! STOP!!! It also says on the tech docs;
"When installing the components to carbon frame/handle bar
surfaces, verify with the manufacturer of the carbon
frame/parts for their recommendation on tightening torque in
order to prevent over tightening that can cause damage to the
carbon material and/or under tightening that can cause lack of
fixing strength for the components."
This is something to be heeded, have a look on the forum at the poor guy that cracked a carbon frame following the above torque settings without reading the note.
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sp3000 - the OP is probably asking because Cannondale's "standard" owner's manual and system six supplement do not have a FD clamp torque specified. And again, it is an alloy seat tube so the chances of cracking it are much lower than for a carbon tube (but of course it is still possible to damage the aluminum).
I have a system six and my sram FD is torqued to 4 N.m and has been problem-free. Like I said in my previous post, "the minimum amount of torque that holds the FD in place is the correct amount." In fact not a single bolt on my bike is torqued to the "recommended max", all are at about 80% of it.
I have a system six and my sram FD is torqued to 4 N.m and has been problem-free. Like I said in my previous post, "the minimum amount of torque that holds the FD in place is the correct amount." In fact not a single bolt on my bike is torqued to the "recommended max", all are at about 80% of it.
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