Torque specs for fork compression plug

[Keith A]

Hey guys & gals,

I'm just finishing up building a bike for my daughter's fiancee. Since he is new to road cycling, I was trying to get everything just right so he wouldn't have any issues with the build. I know there is a fine line between having something tight enough and too tight...especially for carbon fiber. So I've done some searching on the various torque settings, but was curious about the fork compression plug.

I found these instructions from Look which uses an identical compression plug to the one on the Cannodale CAAD 9 fork I have installed...

- Hold the cap in contact on the special ring, with the handlebar stem in the desired position. Screw the expander screw to the recommended torque of 7 to 10 Nm (diagram 3).
- Tighten the cap to a torque of 8 Nm (6 mm Allen key) (diagram 3).

Do these torque setting seem reasonable? I know when I was tightening the compression plug, I stopped before I hit 7 Nm because it felt like I was going beyond the point I would have if I was just going by how it felt.

Any thoughts or input would be welcomed.

[eddief]

you just gotta get the top cap tight enough so the fork turns smoothly in your hand when the front wheel is off the ground. And at the same time the cap needs to be tight enough so when the front wheel is on the ground and you apply the front brake, and rock back and forth, there is no noticable play in the headset. i wonder if anyone does this with a torque wrench. i am usually more concerned about torque of stem on steerer and stem on carbon bars.

i have also found that if you hava a spacer installed above the stem it will sometimes slide a bit and keep the top cap from centering correctly. That can get in the way of being able to correctly preload the bearings and prevent getting things screwed down tight enough.

[ultraman6970]

I do this by ear (per say).. just put some carbon paste in the plug... drop it in... tight just enough so it doesn't turn. put the fork and the top cap, if the plug slides up is clear you need to tight it bit more.

If the fork is used you never know how well the steering column is so pretty much the torque IMO is just a reference, carbon is not steel, a problem in the manufacturing process and the torque recommended could be fatal for the piece. Always put carbon paste to help minimize the torque needed.

The problem with the plugs is that it needs to be the right size, for example fsa ones come like in 2 diameters. Last year i was asking for a compression plug because the one I had did not tight good enough in the fork. So you have to to account that little detail aswell.

Good luck...

[Keith A]

Eddie that's the same way I adjust the top cap, but I was wondering more about the compression plug.

I did a little searching and found Enve's instructions which give more details than the ones from Look and it seems like 7 Nm is the max you should use on a carbon steerer tube. Here's the link if anyone is interested...

http://www.enve.com/manuals.aspx?id=qxcoPJNCEaY%3D

[eddief]

got it now.

Eddie that's the same way I adjust the top cap, but I was wondering more about the compression plug.

I did a little searching and found Enve's instructions which give more details than the ones from Look and it seems like 7 Nm is the max you should use on a carbon steerer tube. Here's the link if anyone is interested...

http://www.enve.com/manuals.aspx?id=qxcoPJNCEaY%3D

[cfox]

enve says 7nm, specialized says 7-9nm. it seems like a lot, but depending on your headset, it takes enough force to pre-load the bearings the plug can easily slip before the pre-load is tight enough.

[jamesau]

The compression plug only needs to be torqued down enough so you can establish preload on the headset bearings. Once you've tightened the stem, you can theoretically remove the plug and ride away.
I usually put some carbon paste on the knurled expander section of the plug thinking it'll get more grip that way.
BTW, love the Enve fork but really dislike the design of their plug. The expander section is a simple knurled slit-sleeve that, when tightened, must apply nonuniform stress on the steerer tube. I thought I'd have to wrench it too much to get it to stay. Much prefer other designs like FSA where expander section expands more symmetrically. It's a bit more complicated and, gasp, probably slightly heavier.
Also, a torque spec is probably only valid for a given model steerer tube used with a particular expander design...
Enve plug pictured below...

[shovelhd]

There are a couple of different types of compression plugs. FSA makes one that has two separate assemblies. The plug assembly goes into the steerer tube. It has a reverse threaded screw with a hex fitting that is used to tighten the plug into the steerer. The torque spec is clearly marked on it. The top cap is a separate assembly that threads into the plug after it is installed. Two assemblies, two torque settings.

Then there is the type shown above, where the entire assembly is dropped into the steerer and the top cap tightened to both expand the plug and tighten the top cap. One assembly, one torque setting.

[cfox]

The compression plug only needs to be torqued down enough so you can establish preload on the headset bearings.

true, but in practice, I've found it takes around 7nm to be tight enough to not slip during pre load. Agree on carbon paste, it's a must. My main problem with the Enve plug is that it's too short and doesn't support the clamping area of the stem.

[Keith A]

Thanks for all the input.

BTW, I really like the Specialized expander plug, but it is no longer listed on their website nor can you find this for sale...

http://www.togoparts.com/items/images/item-lg-19709.jpg

[cfox]

There are a couple of different types of compression plugs. FSA makes one that has two separate assemblies. The plug assembly goes into the steerer tube. It has a reverse threaded screw with a hex fitting that is used to tighten the plug into the steerer. The torque spec is clearly marked on it. The top cap is a separate assembly that threads into the plug after it is installed. Two assemblies, two torque settings.

Then there is the type shown above, where the entire assembly is dropped into the steerer and the top cap tightened to both expand the plug and tighten the top cap. One assembly, one torque setting.

the Enve plug pictured is 2 parts, that picture just happens to have the top cap screwed into the plug. Even the "one piece" plugs like the old Reynolds plugs still needed 2 separate adjustments.

[dougf]

Look (and TIME) don't use the top cap to set bearing preload - they both have proprietary headset systems with silly threaded parts. 7-10 Nm is far too much torque for an expander plug. Every carbon steerer fork I've had I've aimed for around 5nm on the plug.

[Keith A]

Just a FYI...not all Looks are that way, I have a 585 that has a standard expander/compression plug and top cap. It looks just like this FSA one...

http://www.pricepoint.com/images/styleImages/D_318%20FSACM9.jpg

[dougf]

You are right, they don't use their Headfit system on all their frames - I was thinking it might explain why the torque specs were so high in the quote in the OP, but I'm just guessing here.

[Keith A]

You are right, they don't use their Headfit system on all their frames - I was thinking it might explain why the torque specs were so high in the quote in the OP, but I'm just guessing here.I actually pulled this info from a Look PDF that gave instructions for the regular IS headset...
http://www.lookcycle.com/media/catalog/product/f/i/file_3_3.pdf