HELP (head set bearing for my TREK 5900)

Discuss light weight issues concerning road bikes & parts.
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Location: France Northern

by Romano


I am looking for a headset bearing for my "old" TREK 5900 year 2001.

Upper bearing is a Cane creek S6 so no problem but the lower bearing is specific for the Trek with the conic carbon fork (same as Klein).

Measure are:
d: 33,2 mm
D: 44,2 mm
b: 7mm

So I can't find it in France somebody know where to find that ??? :cry:

Thanks a lot, a lot for your help.


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by Weenie

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by Lemondpoprad

call Trek in Europe and ask if they have one.

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Joined: Tue Dec 28, 2004 9:09 pm
Location: Germany


As far as I know the lower headset cup is molded directly into the frame and cannot be removed. This is made on the models 5900 Superlight from 2001 to 2003. The 2004 version has normal headset in it!

You should try to change the lower bearing only! Take the measures of it and go to the next metal hardware shop that has bearings in stock.

But genrerally I second Lemondpoprad's opinion: ask Trek Europe (in Netherlands) for any help!

BTW: I would kill to get a good-in-shape 5900 Superlight in 58 cm from 2003! :evil: IMO it's one of the nicest frames ever made by Trek.

Well, I think I have to live with my Trek Madone bikes: one is the Madone 5.9 from 2004, the other is a 2005 Madone SL 5.9 Andromeda! 8)
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by Griswald4x4

Yeah...Good luck with that. We tried to get one for one of the racers on our Team, US Masters Champ, and couldnt find that fork to save our lives. Id call Trek, and likely you will have to call Wisconsin themselves (Trek HQ). You may be able to find something, we had to get our guy a new frame because there were none of the forks or frames left, Good luck though.

big steve
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by big steve

OCLV wrote:one of the nicest frames ever made by Trek.


The 5900 Superlight was the original road bike I always wanted to have, but infortunatly I was only 16 at the time and couldnt affrdo to buy one, and neither could my parents so I had to settle for a 100 instead!

Also +1 for calling Trek Europe, most likely people to be able to help you.

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by breker

I have the same bike for sale and i have the same problem whit that bearing that ar no stock bearings from SKF .

If somone is intersted in the bike...... it is a 56 ful RECORD in top condition

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by Coppi51

If you can part with your bike for a few can send it back to Trek for a new fork and standard headtube (1 1/8") insert.

The headset on my 2003 5900 recently went bad also. Replaced the top bearings and finessed the bottom a bit so it could work for some late season races...

But this winter I will be sending it back to Trek where it will receive a 1 1/8" steerer and new headset under warranty...or so I am told thru the LBS.

Anyway, not sure if Trek Europe offers that...but worth a shot! Good luck!

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Location: WI

by Cat1

When I had my 5900 with that fixed lower headset bearing it was nothing but problems. My bike shop sent the frame back to Trek and they put in a standard headset race and then I was able to use regular headsets. Trek didnt charge me anything to do this.

I would check with your shop, I know Trek will remove those fixed cups and bond in a standard HS race.

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Location: France Northern

by Romano

Thanks for all your infos. :D

Do you have email of trek europe ?

Unfortunately the LBS where I bought the frame doesn't sell TREK :cry:
difficult to ask other LBS to help me, some of them have already refused.

Hope I will find a solution.


Live to ride, ride to live...

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Location: France Northern

by Romano

Perhaps KLEIN can help me ????

I think it is the same fork as KLEIN so the same lower bearing !!!!


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Joined: Tue Dec 28, 2004 9:09 pm
Location: Germany


Possible BUT Klein isn't represented in europe anymore! They don't sell their bikes here - only in the usa. Maybe the sold not much enough so it wasn't a good deal for Trek which owns Klein!

But: if Trek could remove the lower cup and install a normal 1 1/8" headset race it would be possible to install a normal headset -ideally a King! :wink:

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by madcow

The lower bearing is press fit to the fork, and it is removable and replaceable. The durability of them was not good which was one of the reasons Trek stopped with that design.

As someone mentioned, you can have Trek put a traditional headtube and fork of the bike though.

There are no after market bearings for that headset, you will need to get it direct from Trek, and they aren't cheap. Last time I looked they were around $50 US for the single bearing.

If you don't have any luck sourcing one in Europe, drop me a PM, and I'll arrange to get you one, they are quite common here.

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50 bucks isn't too expensive although a good working standard headset (King) is the better solution.
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by MoreRideTime

madcow wrote:There are no after market bearings for that headset, you will need to get it direct from Trek, and they aren't cheap. Last time I looked they were around $50 US for the single bearing.

Holy cow that's expensive. I just had the lower bearing replaced in my '02 5900 this May and my LBS charged me about 30 bucks. They had to order the bearing from Trek but they did get it. And yes these bearings are not the best. This is my third one in the bike.

I will have to inquire about having the lower cup replaced. For those that have had this done, did you purchase a new fork or did Trek swap it for you?

by Weenie

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by thebikeguyHouston

FYI - As of January 2017, you can still get the headset bearings for a 5900 through Trek. They are an unusual size (the bottom particularly) and have a specific taper and installation direction. So, you may want to just go ahead and have your local TREK dealer do the repair for you.

This bearing was also used in some of the Klein bikes... perhaps even before TREK used it... so the part is called "Headset Part Klein MC2 Airhead Bearing MD OD=1.75in" internally by TREK. Their SKU # is 971605 for this part. UPC is 601842018330.

TREK will not sell this bearing to you directly. You will have to order it through an authorized dealer. I paid $25 for the bottom bearing--which is the one that is odd-sized (due to a taper in the aluminum steerer tube). I watched the tech install the bearing and his method was to install it in the cup mounted to the headtube first... the install the fork as far as it would easily go. Then use stem assembly / bolt to pull the fork the rest of the way up into the head tube. Nice and easy.

I definitely think it is a bullshit move by any bicycle frame / fork / headset designer to use an odd-sized, impossible to find bearing like this one. What if I'm touring across Africa when my bearing goes out? I should be able to go to any local / typical bike shop or bearing supply house and get a bearing that will work for whatever bike I am riding... even if just temporarily. (But, of course, I probably wouldn't be touring across Africa on a early 2000's Trek 5900 frame.)

But I did spend hours trying to find this bearing online and locally. I went to the big bearing distributor here in Houston--that sells pretty much every bearing manufactured in the world--and they didn't have anyting that would work for this headset. Finally it dawned on me to just contact TREK directly to see what they had to say. And that turned out to be the only solution. But what happens if I own a 5900 and I live in a city or area that has not TREK dealer? TREK should definitely sell this bearing--and other odd parts like this for their bikes--online--directly to the their customers.

Also, $25 for a bearing that costs less than $5 to manufacture--probably closer to $2--is outrageous. Just shows TREK really doesn't give a shit about anyone other than the original buyer of their bikes. If I'm the 2nd owner of a TREK bike... I'm still a TREK customer... aren't I?
Trek 5900 headset bearing.png
Screenshot of image TREK pasted into our online / support Chat.

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