modifying threaded headsets for threadless use?

[d_douglas]

Has anybody out there modified a threaded headset for use with a threadless system? I know a bikeshop owner with a creative side who used a Deore LX threaded HS on his threadless Salsa CX bike and wondered if this could safely be done for my bike? It seems that the system is the same, and you just use a different clamping mechanism than the threaded lockring to hold the fork, stem and bars (?)

I ask because I have a very nice Mavic HS that I would like to keep, but at the moment it cannot be used with my threadless system - I was wondering if anyone has done this, could recommend this?

Obviously, the alternative is to find a decent 1" threadless HS or a used King HS and install it as it was originally designed, but my love for Mavic stuff is pretty strong...

Thanks for your replies,

Darren

[93legendti]

How about this:

http://cgi.ebay.com/Nitto-MT-Column-Threadless-Stem-Adapter_W0QQitemZ130116882364QQihZ003QQcategoryZ27 951QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

[Ti Designs]

The difference between the systems is that the threadless one uses some method of centering the top race on the steerer and applies the compression from the top and the lock-down from the stem. The threaded system does all that by locking against the threads of the fork. If it's the mavic headset I'm thinking of with the lockdown screw, there is a center section of the threaded part that restricts which acts as the lock-down.

The threades of a threaded steerer tube are cut into the steerer, not rolled. This means the base diameter of the headset is the same as the steerer diameter without threads, and the threads of the headset extend inward. Removal of the threads brings the diameter of what started out as a threaded headset to the diameter of a threadless headset.

Threadless systems have a number of ways of centering the race. One way is to use a chamfered surface with a split collet. Chris King uses high tolorances and a rubber O-ring, which seems to do the trick. As long as you have the headset on the lathe to remove the threads, why not cut the a channel for the O-ring? If it's the Mavic headset with the lockdown screw you need to be dead on with the cutting process. Otherwise using the lockdown screw will shift the top race of the headset and the whole thing will bind. Better yet, as the preload and lock-down will be done by the stem and top cap, why not remove the screw (with the rubber cover nobody will know) and machine a flat surface on top to mate with the spacers.

[d_douglas]

Ti Designs get it and it sounds like it can be done, but at a fairly great degree of hassle. If I do it right (or get a pro to do it) I assume from your detailed response that this should work, right? It is not the end of the world, but it would be cool to use this beautiful old boat anchor.

93 Legend ti: I am looking at using a threaded type headset on an entirely threadless system. As it stands, the bike uses an old, cheap and worn Ritchey Logic threadless system that needs replacing. It is all modern (except for the 1" factor), so I need to modernize my old fashioned headset for this to work.

The shop owner guy simply took the lockring off and crancked down the stem on the remainder of the heaset assembly. It looked OK to me, but he was experimenting and I am not in the position of ovalizing my HT or ruining a new headset just for the sake of trial and error.

Good points!

[KJMUNC]

I converted a Dura Ace 7410 threaded headset to threadless out of pure vanity to keep my early 90's period build correct despite a threadless fork on my Merckx MX Leader

I used a Dremel tool with a carbide bit to carve out the threads on the adjusting nut and top nut. Be sure to hold the piece you're carving with a soft vice or an insulated glove, as the friction will heat it up quickly. You'll have to just eyeball how much material to remove and keep fitting it to the steerer tube until it cleanly slides down without snagging. Then you can use both pieces as spacers and install your threaded stem business as usual.

[gdw]

Anyone remember the Wheeler MTB's from the early 90's. They made a hybrid fork which used both systems...sort of. The forks were designed to use 1 1/8in threaded headsets and 1in clamp-on, non quill, stems. They had a double diameter steering tube which was 1 1/8in wide from the race to the top of the threads which then rapidly tapered down to 1in width above the threads. The final 2 inches of the steerer were smooth to accept a 1in clamp-on stem. It's was a bizarre design which didn't catch on and may be one of the reasons why Wheeler didn't survive in the US.

[Too Tall]

Has anybody out there modified a threaded headset for use with a threadless system? I know a bikeshop owner with a creative side who used a Deore LX threaded HS on his threadless Salsa CX bike and wondered if this could safely be done for my bike? It seems that the system is the same, and you just use a different clamping mechanism than the threaded lockring to hold the fork, stem and bars (?)

I ask because I have a very nice Mavic HS that I would like to keep, but at the moment it cannot be used with my threadless system - I was wondering if anyone has done this, could recommend this?

Obviously, the alternative is to find a decent 1" threadless HS or a used King HS and install it as it was originally designed, but my love for Mavic stuff is pretty strong...

Thanks for your replies,

Darren


Darren I was bitting my lip 'cuase am not sure I remember all the details. As I recall about 8 or 9 yrs. ago Le Tour mechanics were modifying XT headsets for TDF bikes because the end result was really light.

[Big Dan]

Done it to a Shimano headset and worked fine.
A file and a couple of cold beers.......

:cool:

[d_douglas]

So, the catch is that I am using a weird headset and not a normal Shimano type one, but it sounds as though this is a possibility. I guess there is no going back once I file off those threads!

On that note, is it actually necessary to use the lockring? Can't you just put the stem up against the top race of the headset? Or just put a 3mm spacer on top and them 'apply the stem'?

Good news, though...