# Bolt torques on carbon?



## Shuteye (Nov 25, 2006)

As I've posted previously, I'm building up a Look 585, my 1st carbon bike. I now have all the bits, and am assembling. Regarding bolt torques at the front derailleur clamp, the stem, and the threaded brake sleeves, will carbon withstand torques close to the manufacturer recommended max torques (ie: my Deda stem has a max of 8nM at the steerer clamp)? I try to be careful not to torque to the max, but am wondering if I need to be VERY careful with carbon (past bikes were steel and ti).


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## C-40 (Feb 4, 2004)

*common sense...*

There is no need to tighten the steering tube clamp bolts to 8Nm to hold the stem in place. As little as 5nm would probably do fine.

That siad, I've never used a torque wrench on small M5 or M6 bolts. If you can't do this by feel, how do you ever manage to make an adjustment on the road?

FWIW, I once tried to damage an unsupported section of LOOK steering tube by tightening a stem with two M6 bolts with all the force I could muster, using a long hex wrench, but it didn't hurt a thing. I've also put a piece of steering tube in a vice to see what it took to fracture the tube. I got it to break, but it was severely egg shaped before any permanent damage occurred.


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## Shuteye (Nov 25, 2006)

Thanks, C40. That helps. Intuitively I knew this, but carbon has me a bit spooked as to well localized pressure points. I'm sure a few rides and adjustments and I'll be over it.


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## ElanS3 (Nov 1, 2005)

*Bottom bracket*

I´m also building a 585 and have notised that the bearing adaptors torque is 35 - 50 Nm. Reports of the threaded bushings in the bottom bracket coming loose, have circulated. To much torque or pedal force?


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## C-40 (Feb 4, 2004)

*neither one...*



ElanS3 said:


> I´m also building a 585 and have notised that the bearing adaptors torque is 35 - 50 Nm. Reports of the threaded bushings in the bottom bracket coming loose, have circulated. To much torque or pedal force?


If the aluminum insert in the BB comes loose, it's usually a case of poor bonding during the build. I haven't heard any recent reports of this problem with LOOK products.


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## Kilian (Dec 29, 2006)

*HSC4 Steerer tube Crushed*

Be careful with the carbon steerer tubes, On a return trip from France last year I found out that mine was crushed on my KG381.
Also, Eastonbike.com has some PDFs on torgue specs that is useful. I bought a Park Tools torque wrench and use it faithfully..


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## C-40 (Feb 4, 2004)

*crushed??*

What "crushed" your steerer; bagage handling? If you use a torque wrench it should never be damage during normal installation.

What do faithful users of torque wrenches do to make an adjustment out on the road?


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## filtersweep (Feb 4, 2004)

Does it really have a clamp on front derailleur? That seems a little strange.



Shuteye said:


> As I've posted previously, I'm building up a Look 585, my 1st carbon bike. I now have all the bits, and am assembling. Regarding bolt torques at the front derailleur clamp, the stem, and the threaded brake sleeves, will carbon withstand torques close to the manufacturer recommended max torques (ie: my Deda stem has a max of 8nM at the steerer clamp)? I try to be careful not to torque to the max, but am wondering if I need to be VERY careful with carbon (past bikes were steel and ti).


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## C-40 (Feb 4, 2004)

*yes...*

I think you'll find the majority, perhaps all, current models use a clamp on FD. Both my 585 and 461 do.

I personally prefer a clamp-on adapter combined with a braze-on FD. 

The other option that some brands now choose is a very long braze-on mount to cover doubles, triples that mount higher and compacts that mount lower.


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## Shuteye (Nov 25, 2006)

As C40 said, no braze on fitting on the seat tube. The frame is well marked like a handlebar with centering lines for adjustment purposes. 

Regarding adjustments in the field C40, I agree as I think would most torque wrench users, absolutely no need for a torque wrench. Realistically, field adjustments are cable stretch, limit screws, and saddle height. I get my bar and shifter adjustments done with around the block and back to the shop spins, but neither need torque measurements in my opinion. 

For carbon steerers and seat tubes this thread has made me feel more comfortable now that I know how durable carbon is - thanks y'all. That said, I plan to know the torque of both stem on steerer and FD clamp on seat tube. Makes me feel better as these components may not be touched for years once dialed in. At least on my bike they're not - maybe I'm just lazy  . But....crankarm, BB torques are faithfully done with a torque wrench whenever I swap components or build a frameset and I have already done this with my 585. These I gotta know, man!


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## filtersweep (Feb 4, 2004)

the old 81 series had the braze on mount--- at least mine does.



C-40 said:


> I think you'll find the majority, perhaps all, current models use a clamp on FD. Both my 585 and 461 do.
> 
> I personally prefer a clamp-on adapter combined with a braze-on FD.
> 
> The other option that some brands now choose is a very long braze-on mount to cover doubles, triples that mount higher and compacts that mount lower.


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## Shuteye (Nov 25, 2006)

BTW, Campy calls for 32-38 N.m torque on the crankbolts for the 2006 carbon crankset with a square taper BB. Using a torque wrench, that is one heck of a lot of force! Even 30 N.m is in excess of 250 in.lb and they are specific about NOT lubing the bolts - I'm sure so that excess compression is not put on the crankarm/square taper interface, potentially deforming the crank. I know early in my cycling days (1985) I failed to torque a crank bolt sufficiently and had the crank come loose on a ride. Rode 15 miles home one legged so as not to screw up the crankarm. I don't mean to open up a "to lube or not to lube" discussion - I'll stick with Campy's instructions - no lube on square taper and no lube on the bolts.

Regarding the BB supports (no longer called cups I'm sure due to cartridge design), Campy calls for 70 N.m. If there is bind, Campy says to back off to 30 N.m. I am honestly not comfortable torqueing past 30 N.m. I was carefully watching the Look BB insert the whole time I was tightening. I know a lot of abuse is dished out to this area over years of riding so all fasteners must be well tightened. Any comments? As in my original post, just to make me feel better or warn me of potential damage :thumbsup: .


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## Scotland Boy (Nov 11, 2004)

ElanS3 said:


> I´m also building a 585 and have notised that the bearing adaptors torque is 35 - 50 Nm. Reports of the threaded bushings in the bottom bracket coming loose, have circulated. To much torque or pedal force?


Sorry to hyjack but the aluminium bottom bracket threads of my 585 came loose when I was replacing my bottom bracket component. Kinda glad to hear that some others have had the same problems. The frame is being replaced by Look which is very good. Thanks guys.

As for special treatment for carbon when tightening f mechs and so on, I always thought the maximum torque value was for the bolt, not the carbon. Carbon is very strong and as C40 demonstrated it takes a lot for it to fail.

SB


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## chas (Aug 10, 2006)

Scotland Boy said:


> As for special treatment for carbon when tightening f mechs and so on, I always thought the maximum torque value was for the bolt, not the carbon. Carbon is very strong and as C40 demonstrated it takes a lot for it to fail.
> 
> SB


Carbon is very strong, however the point on the seat tube where the front derailleur clamps is relatively thin; especially compared to a steerer tube. I have seen several frames returned to us that have cracked seat tubes resulting from overtightening front derailleurs. Additionally, this is not an issue unique to carbon. I have also seen over-tightened front derailleurs dent seat tubes on steel and aluminum bikes.

Best thing is to use a torque wrench. Front derailleurs don't require all that much torque to keep them in place.

*[email protected]*


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## 800lbgorilla (Aug 1, 2005)

*Chas..*

Does Look recommend a maximum torque for the FD clamp (probably less than the max torque for the FD clamp bolt)?
Thanks


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## Kilian (Dec 29, 2006)

*What Crushed it?*

I must have overtightened it in France. I DID NOT have a torque wrench before that. Hence the advice to all to get one!

As for on the road adjustments, I rarely ever have to, but that's when you need to know about how much torque that it takes. Using the torque wrench regularly helps me to have a better idea instead of guessing.


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## HammerTime-TheOriginal (Mar 29, 2006)

800lbgorilla said:


> Does Look recommend a maximum torque for the FD clamp (probably less than the max torque for the FD clamp bolt)?
> Thanks


Chas or Tino,

Can you weigh in here? Thanks.


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## I_Need_Training_Wheels (Sep 16, 2005)

Hey Shuteye, Thanks for bringing this topic up. I've been wondering about torque specs as well. I have a 585 from '05 and have begun changing components myself and would also feel comfortable knowing the right amount of torque to apply, in particular for the seatpost.

Chaz or any Look owner, is there some sort of spec sheet out there that shows torque specs for each attachment point?


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## wArden (Dec 20, 2007)

There would not be any specific torque specs because you are tightening something onto carbon fibre. Instead there would be a maximum torque based on the type of bolt you are using. Therefore, the manufacture of the front derailleur should be specifying how much torque to use.

Generally people often way over-tighten bolts. You would be surprised how little torque parts require.

Best money spent would be to invest in a good torque wrench.


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## Shuteye (Nov 25, 2006)

Interesting to see this topic come up again as this thread lay dormant for more than one year. I was moved to respond as my 585 is now built and ridden. What is interesting to think back on, once the bike was built up carefully and torqued to spec, no field adjustments beyond initial seat height were needed (an adjustment for which I have never used a torque wrench). I just get on my bike an ride. The 585 ain't a bad ride either! 

That said, I will always have a soft spot in my heart for my first good bike, a 70's Colnago SL Super. The frameset still hangs on the wall in my shop and will always bring back great USCF cat 4 and 3 memories. Kind of like the feeling I have for Mary Johnson, the first girl I ever made out with (on a snowy night in Fort Wayne, Indiana in the back of a 52 Chevy, huge back seat).

But I digress, as wArden says, best money spent is on a good torque wrench.


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