# Klein MC3 Stem Question



## bryanus (Jun 1, 2008)

I've been trying to STF, but nothing seems to come up for me. It's weird...

Anyway, I've been reading a few things about MC3 stems and such. Will the MC3 stem work on a MC2 fork?

I know there are different versions of the MC3, so I am a little confused on that point. The MC2 bar I have now is nice, but I wish it had a little more rise to it. And since it seems like I'll never find an MC2 bar with what I want, I was looking into this MC3 question a bit.

Were the first MC3's compatible with the MC2 forks? Anyone know where I can find one?


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## Guest (Dec 6, 2008)

there's only one MC3 MTB stem version and one (smaller clamp) MC3 road version. the MC3 MTB stem will fit on the MC2 fork, it's the same steerer tube. the airhead was MC3 first and MC3.1 later but that refers only to the way how the upper bearings is fitted into the head tube - not with the steerer tube and stem.

the MC3 has a different spacer/head tube cap design which is quite neat










Technically you don't need them, the MC2 plastic spacers will work as well or you can leave them completely off but the conical shaped top cap looks nicer. You should be able to get those parts through any Trek dealer. Part numbers are

Airhead Top Cap (MC3) 993828
Airhead MC3 Top plug 992584 (usually doesn't come with the stem)
Top bearing spacer 992581
10mm spacer 992578
5mm spacer 992577

Icycles had some of the MC3 stems for cheap

https://www.icyclesusa.com/catalog/klein-mc3-1-18-inch-threadless-mtb-stem.htm
don't be irritated by the 1 1/8", that's wrong.

https://www.bikeman.com/content/view/337/31/ might be sold out

They often pop up on ebay and don't go for much. Scant on here had some too. Just make sure that you get the larger one, not the road version.

More info can be found here

https://www.kleinjapan.com/tech_guide/2001_klein_tech_manual.pdf

Carsten


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## bryanus (Jun 1, 2008)

Frikken awesome information! I was just looking at hose at icycleusa, but the 1-1/8 made me think there were different sizes of these stems, hence the version numbers. This is great news to me. Thanks Carsten!


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## bryanus (Jun 1, 2008)

Carsten, ever seen one of these, or know who makes it? Is it made by Klein/Trek to allow the Mantras to run standard forks?

https://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=370121095290&ssPageName=STRK:MEWA:IT&ih=024

Here' the details, in case it's pulled:



> This auction is for an extremely rare & hard to find Klein MC2 & MC3 headset adapter kit. Basically using these machined pieces you can install a conventional 11/8 fork of you choice into any Klein with a MC2 or MC3 headset. For those fanatical klein lovers who are looking for a degree of comfort & the ability to fit some modern suspension forks, this is the answer you've been looking for! Generally its in superb, fully functional condition. Theres a tiny bit of burring from removal, this doesnt affect performance in any way & could be easily tidied up if required. Its so unobtrusive you probably wouldnt see it when installed anyway. This adapter works perfectly with the Klein Mantra Race carbon frame in my other current auctions. This is your chance to pick up an exceptionally rare & hard to find part, for a fraction of its previous high retail price.


I aksed the seller how it worked and he said:



> ...the existing bearings stay in place, you just drift out the existing forks, and remove the top bearing spacers etc.
> 
> Place the deepest section piece as pictured onto you 1.125 steerer fork and tap it right down onto the crown- like a conventional bearing race.
> 
> ...


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## Guest (Dec 8, 2008)

yes, that's the Klein/Trek 1 1/8" conversion kit for the MC3.1 head sets. While it can be fitted on the MC3 and MC2 head sets (same bearings as the MC3.1) it is not supposed to be used on the older head sets. On those the upper bearing is pressed in from the bottom of the head tube and thus it may be pushed down if you apply load to it via the ahead stem and the adapter. The top reducer (top left on the pic) will then bottom out on the head tube and/or bearing and steering will be less optimal. On the MC3.1 the upper bearing is pressed in from the top and thus there's no risk of that to happen. 

I've seen people using it on the MC2 frames though and it's a relatively cheap conversion. Leucadiabikes offers them for $70 but any Trek dealer should be able to order them. I think Trek still stocks them. But i wouldn't do it.

Carsten


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## bryanus (Jun 1, 2008)

Thanks again, Carsten. That makes more sense now. Compressing the bearings from the top on the bottom-pressed MC2 airheadset does seem problematic.

I've been learning quite a bit about Kleins in the past month!

BTW, i took out my Adroit on its virgin ride (to me) yesterday. It was great! The stem may be a good fit for me afterall, and the FSX lowers I installed along with the newly sealed Total Air cartridges works fantastic and the action is much better than I expected for such an old fork. I did have an annoying top-out on the forks, but when I got home I took it apart and found that the top-put compression rubbers had all but disintegrated over the years. So I cut an old Judy elastomer to the right size and used that as a temporary fix, but it immediately got rid of the top-put knock. I'm sure I'll find a better suited material to use as a more permanent fix soon. It's just a flexy piece of polyeurethane material the size of about 3 stacked quarters. Sort of like a skateboard wheel material, but softer.


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## PhotoGus (May 14, 2008)

Is Carsten still around? He only comes up as a guest on these forums, but I've seen him pop up left and right with great info on old Kleins and was hoping to get some info. Thanks.


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## eastcoaststeve (Sep 19, 2007)

PhotoGus said:


> Is Carsten still around? He only comes up as a guest on these forums, but I've seen him pop up left and right with great info on old Kleins and was hoping to get some info. Thanks.


Sadly, no....wish he'd come back though.

Steve


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