Correct torque for top cap

[ronf100]

I have a Serotta CDA with Serotta carbon fork and Chris King headset. What is the correct torque for the top cap? The Chris King instructions only gives a spec for using a star washer and I am using an expansion plug.

Thanks

[Louis]

1) Check the Park Tool web site - they have a list of recommended torques. Not sure if top caps are on there.

2) Keep in mind that all the cap screw does is snug things up and take the freeplay out of the headset. Once the stem-to-steerer tube clamp is tightened it does all the heavy lifting and the top cap can be removed with no ill effects. At that point all that bolt does is hold the cap on. Bottom line: don't over do it.

[eddief]

as i understand it, the only thing the top cap and bolt do is put a preload on the bearings in the headset. once you load the bearings and lock down the preload with your stem/top cap/bolt, then the top cap is just for looks. in my shade tree mechanicals, i load the bearings by tightening the top cap bolt, make sure there is no play by applying front brake and rocking the bike bike back and forth and checking for the wiggle in the bearings...and make sure the steering does not bind at all by getting the tire off the ground and turning the bars from side to side.

on the other hand, i think it is much more important for carbon steerer and carbon bars to torque those bolts to spec.

[pdmtong]

as noted, once the stem is tight the top cap really serves no further purpose as it's the stem now that is holding the fork on - rotate the cap so the logos face the way you want and just snug the bolt...

[rustychisel]

as i understand it, the only thing the top cap and bolt do is put a preload on the bearings in the headset. once you load the bearings and lock down the preload with your stem/top cap/bolt, then the top cap is just for looks. in my shade tree mechanicals, i load the bearings by tightening the top cap bolt, make sure there is no play by applying front brake and rocking the bike bike back and forth and checking for the wiggle in the bearings...and make sure the steering does not bind at all by getting the tire off the ground and turning the bars from side to side.

on the other hand, i think it is much more important for carbon steerer and carbon bars to torque those bolts to spec.


this, in detail

[alancw3]

not sure of the actually torque number but on my serotta with the f3 fork and the old style chris king plug headset it is much higher than on the star type of nut. i had to actually tighten mine three times (last time quite a bit) before i got most of the back and forth "play" out of the headset while braking. chris king website does not give number for this style only the star nut type. i didn't actually put my inch torque wrench on the second and third time but i would quess it was in excess of 25 inch pounds easily. first time i tried the chris king recommmendation for the star nut and that was way too loose. hope this helps. i know i was concerned about over tightening but i don't think that is the case.

[lonoeightysix]

max is 15 inch/lbs, recommended is whatever gets the job done, below that figure.

[ultraman6970]

As long the headset is not too tight that the fork doesnt move you are ok. In other words, just tight it enough so the fork doesnt have play, then tight the stem and you are ready to go. Even afterwards you can take the top cap out to save some grams :P since the stem is the one who holds the front end together.

[AgilisMerlin]

I always thought, once you have achieved the correct tightness to the headset and torqued the stem bolts to the appropriate setting/tightness, then whatever makes you comfortable tightening the cap against the stem.

go to town, but i just made sure it was snug enough not to back out. I would not reef on it as though it was the end of the world.

[dustyrider]

as i understand it, the only thing the top cap and bolt do is put a preload on the bearings in the headset. once you load the bearings and lock down the preload with your stem/top cap/bolt, then the top cap is just for looks. in my shade tree mechanicals, i load the bearings by tightening the top cap bolt, make sure there is no play by applying front brake and rocking the bike bike back and forth and checking for the wiggle in the bearings...and make sure the steering does not bind at all by getting the tire off the ground and turning the bars from side to side.


This is what I do, except I follow that with a spin around the block, being sure to put some heavy forces on the front end, then loosen the stem and, repeat the above.

[Dave]

Appyling the front brake and rocking the bike does not work with the majority of today's bikes that use angular contact bearings. It takes a significant tor que to preload the bearings properly -far more than required for a traditional headset.

Unless you apply so much torque that the front wheel does not readily self-center after a turn, then it's not too much. When too little torque is used, you may hear a thwack sound when the front tire hits a sharp mismatch in the road. That a sure sign that the bearings are not adequately loaded.

Whether a star nut or expanding plug is used has nothing to do with the torque applied to the to cap. Both perform the same function - anchoring the top cap bolt.

[Bob Loblaw]

Why would you want to preload the bearings? Why isn't eliminating the play enough?

Appyling the front brake and rocking the bike does not work with the majority of today's bikes that use angular contact bearings. It takes a significant tor que to preload the bearings properly -far more than required for a traditional headset.

[ronf100]

Thanks for the useful responses

[Dan Le foot]

I have a related question.
On my wife's Ti cross bike with an Enve fork and compression plug, the difference between too tight a head set (Wheel slow to return to center) and too loose is a very, very tiny adjustment. I haven't experienced this before.
I have the same set up on my bike and I can turn the cap an extra half a turn before binding. I did the install/build on both bikes.
Any thoughts?
Dan

[Kontact]

I think this question is a bit like asking what the torque load for a derailleur limit screw is.

After correct preload has been set, I'd suggest torquing down the stem bolts and leaving the top cap at the correct setting. That way if you discover your stem isn't straight or something you don't have to start by re-adjusting the bearing. Normal preload should be tight enough to prevent the bolt loosening on its own.

[Dave]

Why would you want to preload the bearings? Why isn't eliminating the play enough?

I can tell you don't understand angular contact cartride bearings. If a substantial amount of preload is not not used, the lower bearing seat can be be beat to crap. This was a common problem with aluminum frames where the head tube was machined to accept the 45 degree angled bearing. Users who failed to apply enough preload could ruin a head tube, or at least beat it up enough to require remachining. Park Tool sells cutters for this job.

[Kontact]

I can tell you don't understand angular contact cartride bearings. If a substantial amount of preload is not not used, the lower bearing seat can be be beat to crap. This was a common problem with aluminum frames where the head tube was machined to accept the 45 degree angled bearing. Users who failed to apply enough preload could ruin a head tube, or at least beat it up enough to require remachining. Park Tool sells cutters for this job.

Does Cane Creek understand angular contact cartridge bearings?

Pre-loading the Headset Assembly:
With the headset fully assembled and with the stem bolts loose, tighten the headset preload bolt just until slight resistance is felt. Carefully
continue tightening until all play is taken out of the headset assembly, this should require very little force. Align the stem with the front wheel and tighten the stem clamp bolts. Check for play by firmly holding the front brake and rocking the bike backwards and forwards. With the headset properly adjusted there should be no play in the assembly and the fork should rotate easily without binding.

http://www.canecreek.com/manuals/Headset_Instructions/100%20Series/100%20Classic%20Threadless%20Instructions.pdf


It sometimes takes a little force to overcome the resistance of the all the components and seals sliding on the steerer, but the actual preload is nothing more than removing all play.

[Dave]

Does Cane Creek understand angular contact cartridge bearings?

Pre-loading the Headset Assembly:
With the headset fully assembled and with the stem bolts loose, tighten the headset preload bolt just until slight resistance is felt. Carefully
continue tightening until all play is taken out of the headset assembly, this should require very little force. Align the stem with the front wheel and tighten the stem clamp bolts. Check for play by firmly holding the front brake and rocking the bike backwards and forwards. With the headset properly adjusted there should be no play in the assembly and the fork should rotate easily without binding.

http://www.canecreek.com/manuals/Headset_Instructions/100%20Series/100%20Classic%20Threadless%20Instructions.pdf


It sometimes takes a little force to overcome the resistance of the all the components and seals sliding on the steerer, but the actual preload is nothing more than removing all play.

Those who tighten the top cap lightly on an IS or Campy integrated headset won't like the eventual damage to the head tube. That's why most frame brands started using replaceable bearing seats in the head tube -too many folks followed those outdated instructions and ruined the head tube.

I've owned a lot of frames with IS headsets. If you tighten the top cap lightly, you won't feel any play, but the noise that you hear when hitting sharp mismatches in the road is the sound of destruction.

Tighten the top cap as tight as possible without restricting the free movement of the steerer. With an IS headset, it's a substantial amount. The same force applied to a conventional Campy headset would render the steerer unable to move.

[Kontact]

Those who tighten the top cap lightly on an IS or Campy integrated headset won't like the eventual damage to the head tube. That's why most frame brands started using replaceable bearing seats in the head tube -too many folks followed those outdated instructions and ruined the head tube.

I've owned a lot of frames with IS headsets. If you tighten the top cap lightly, you won't feel any play, but the noise that you hear when hitting sharp mismatches in the road is the sound of destruction.

Tighten the top cap as tight as possible without restricting the free movement of the steerer. With an IS headset, it's a substantial amount. The same force applied to a conventional Campy headset would render the steerer unable to move.
I think we're just mixing terms, here. The amount of actual load on the bearings is identical. The amount of force it takes to squeeze everything together can vary, but the actual procedure for eliminating play is the same.

[Dave]

I think we're just mixing terms, here. The amount of actual load on the bearings is identical. The amount of force it takes to squeeze everything together can vary, but the actual procedure for eliminating play is the same.

I've got no clue how you would know what amount of preload is on the bearings. All I know is the old-style headsets require a very light top cap bolt torque, or you'll lock up the steerer. The new integrated headsets with 45 degree anglular contact seats in the head tube require a much greater torque.

Rocking the bike with the front brake locked to feel for play works with the old style headsets, but it's worthless with the new integrated models.

[Kontact]

I've got no clue how you would know what amount of preload is on the bearings. All I know is the old-style headsets require a very light top cap bolt torque, or you'll lock up the steerer. The new integrated headsets with 45 degree anglular contact seats in the head tube require a much greater torque.

Rocking the bike with the front brake locked to feel for play works with the old style headsets, but it's worthless with the new integrated models.

All the inset headset bikes I build and repair (which is an awful lot) are adjusted so the headset turns without binding or play - that's how I know how much preload the bearings have. I tighten until they start to bind, then back the adjustment off and lock it. I "rock for play" only to validate the adjustment I made in the stand, and almost never have to re-do it.

No, we don't have a rash of failed headsets from following this procedure, which is the same as Cane Creek's.