shane45

I didn't think this would be so difficult to find...

Easton has not returned my call (or email). Google is hopeless. Search of this forum talks a lot about proper torque, but not one of the posts I saw actually told me the spec.

Regardless, can someone please tell me what the correct in.-lbs. is for an Easton Monkeylite composite (ie. CARBON) bar as used with a 2-bolt stem faceplate?

sydney

Duno,but this tool handles it all. www.sheldonbrown.com/tork-grip.

shane45

I knew one of you bastids would suggest that - I just didn't think it would be so soon!

Retro Grouch 

Try to find a torque spec for your stem. Isn't that what you are really tightening?

shane45

Correct, but I doubt that the torque spec. indicated on my Easton EA50 stem (70 in.-lbs.) is the same for aluminum vs. carbon bars.

(Or is it?)

Retro Grouch 

Why wouldn't it be? You can't baby the clamp force just because it's a carbon bar. You have to have a certain minimum amount of clamp pressure to hold the bar secure regardless of it's material. Uh - your stem does have the correct clamp diameter doesn't it?

Incidentally, 70 in/lbs isn't very much. If you tighten your stem by "feel" you will almost surely exceed 70 in/lbs. One of the nice things about using a torque wrench is that it allows you to get the two fasteners equally tight. That gives you more even clamping pressure across the face of your stem. Gradually walking the torque up to 70 in/lbs in steps is even better.

shane45

Uh - is that important?



(Yeah, it's a 25.4mm stem with a 25.4mm bar.)

neil0502

Here's Sheldon Brown's response to a similar question, posted on Usenet:

Now . . . that said . . . here. This should give you a pretty good idea:

https://www.velonews.com/media/easton_bolt.pdf

dmw010

I have to disagree and urge caution. The recommended torque values for a carbon bar ARE different for my several-years-old Ritchey WCS stem. For a non-carbon bar, they recommended something like 55in-lb, but only 35 for carbon. And my bar has not slipped, even with the lower torque.

Raiyn

I'll back this up too. Carbon is a bit more finicky when it comes to torque specs. Unfortunately I don't have the proper number to give at the moment

neil0502

'twas in the link I posted . . . from Easton directly:

https://www.velonews.com/media/easton_bolt.pdf

(no respect. No respect, I tell ya... )

Raiyn

So it is....

rmfnla

Good article.

It mentions maximum torque for bolts but does not address the fact that fasteners are designed to stay secure when they are being "stretched" slightly, which is what recommended torque is designed to accomplish. Undertightening does not achieve this so the bolt backs out & the part comes loose. Overtighening exceeds the tensile limits causing the bolt to fail. Bolting into softer materials like aluminum complicates things further because it's that much easier to strip the threads.

I don't know the answer, just wanted to point out some tech-geek stuff.

neil0502

Preload. Sure, but . . . theoretically . . . a manufacturer who is putting out a torque spec is also creating the spec for the fastener that they designate, so the elasticity is supposed to be factored in when they tell you how much torque to apply.

Do they actually do that? Who knows....

https://www.parktool.com/repair_help/torque.shtml

rmfnla

Exactly, but they are not specifying what is being clamped by the fastener (carbon bar vs. aluminum) so carbon's relative fragility (is that a word?) is not being taken into account.

rmfnla

BTW, preload is another thing entirely.

neil0502

You're right. I stand corrected.

https://www.rockcrawler.com/techrepor...rque/index.asp

rmfnla

's cool.

neil0502

Actually, the more I look at it, I'm not sure my use of 'preload' was incorrect.

Can you point me to a source that shows explains your different usage??

Here are a few I referenced:

... https://composite.about.com/library/g...bldef-b725.htm

... https://news.thomasnet.com/IMT/archiv...sics_of_t.html

... https://euler9.tripod.com/fasteners/preload.html

I'd be grateful for the education....

shane45

Cool - thanks!

rmfnla

Well, terms can be used differently in various disciplines, but my experience with preload is with springs and bearings, where there is an expected force (load) in it's usage and some initial force (preload) used in the installation.

I think in this case we are trying to figure the relationship between bolt torque and clamping force.
I don't have much experience w/ carbon bars (too expensive) so I can only postulate (fancy word for guess).

Whew, fixing stuff is fun; writing about it is a bit more effort!

neil0502

You go ahead and postulate all you want. I'll be over here . . . pontificating with reckless abandon

Now where's my second cup of coffee. I'll show you preload....

shane45

Here's the emailed reply I got from Rick Wilks at Easton:

*******************
Hi Shane,
The torque values (as appearing on the stem) are for either carbon or aluminum.
Cheers
Rick
*******************

So it appears (at least when using an Easton stem as I indicated I was to them) that torque is the same whether you have a metal or composite bar in the stem. (70 in.-lbs. in the case of my EA50 stem).

neil0502

Another thing worth mentioning about carbon is that you don't grease it prior to clamping (primarily applies to the seatpost).

If you do, it will require more force to secure it than the post is intended to endure, risking catastrophic failure.

For me, that's not very OT at all

rmfnla