Klein MC2, MC3, MC3.1 Adroit + Mantra Cane Creek IS Headset Conversion

My newest headset conversion kits are ready to go! I have three models. One for older MC2/MC3 Kleins (top bearing loads from the bottom of the headtube), one for MC3.1 Adroits (top bearing loads from top), and one for MC3.1 Mantras (top bearing loads from top).

These kits convert the Mission Control bearings to standard Cane Creek 1 1/8″ IS bearings. Kits include an Aheadset with full compliment semi-cartridge bearings. Fork crown race sits recessed into the lower cup to keep the elements out, upper bearing cap sits dead flush on the top of the headtube to keep water and grit out of that bearing also.

Users can swap bearings to any IS bearing/crown race. They’re all standard parts. If you want to run the super-sealed Cane Creek 110 bearings, they drop right in. Lower crown races with the integrated seal work fine too.

This kit also has the lowest stack height physically possible, so you can run a fork with about 1″ more travel than stock without altering the geometry. Everything sits just about dead flush with the top and bottom of the headtube.

UPDATE: I now have 4 different lower race stack heights available: 0, +4, +8, and +12 mm. This allows you to set the geometry of the front end to your preferences and more importantly provides adequate clearance for the crown of wider forks to clear the downtube. Some Adroit owners were finding that going to a 32 mm fork like a Fox with the zero stack headset resulted in the adjuster caps hitting the downtube if the bars swung around. This is no longer an issue. See the images below and the updated MC2/3 gallery.

Headset Cups

Headset Cups

Instructions for ALL kits are shown below.

If you’d like a set for your bike, post a comment here or post in the forums and I’ll get back to you.

Forum Link

Thumbnail Gallery of MC3.1 cups installed in my Carbon Mantra frame

Thumbnail Gallery of MC2/MC3 cups installed in a customer’s Adroit frame

Installation Guide (Click Photos for Larger Image)

Headset Cups

Step 1: Remove fork and upper/lower bearings. A plastic hammer and a dowel work well for removing the fork and driving the bearings out.

Headset Cups

Step 2: Scrape the old loctite out of the headtube bearing register.

Headset Cups

Step 3: Swab out the rest of the remaining loctite with acetone or similar. A clean headtube is key to having the cups sit square.

Headset Cups

Step 4: It should look nice and clean like this.

Headset Cups

Step 5: Apply some Loctite RC 660 or RC 680 to the headtube. Be sure to get it down into L at the bottom of the bearing register.

Headset Cups

Step 6: Apply a thin coat of RC 660 or RC 680 to the upper bearing cup.

Headset Cups

Step 7: Insert cup into headtube with a slight twisting motion. If cup is a tight fit, use a wooden block to whack it in. Be sure that it goes in straight (not cocked to once side or the other). For MC2/3 upper cup inserts from the bottom. Make sure setscrews are backed off before inserting. Use a dowel to whack it into place. Once seated, tighten the three grub screws snug so that they lock the upper race in place. Tighten until they are flush with the bearing surface.

Headset Cups
Headset Cups

Step 8: When finished it will look like so (MC3.1 upper photo, MC2/3 lower photo)

Headset Cups

Step 9: Wipe off excess loctite.

Headset Cups

Step 10: Upper cup installation finished.

Headset Cups

Step 11: Now to the bottom cup.

Headset Cups

Step 12: Clean the bottom register with a screwdriver and acetone swab like you did on the upper register. It should look clean and pretty like this when done.

Headset Cups

Step 13: Apply RC 660 or RC 680 like you did with the upper register. Again be sure to get some down on the L at the bottom where the bearing cup will rest.

Headset Cups

Step 14: Apply RC 660 or RC 680 to the lower bearing cup.

Headset Cups

Step 15: Insert with a twisting motion. Use a block of wood to whack the cup in if it’s a tight fit.

Headset Cups
Headset Cups

Step 16: Wipe off excess loctite. Should look nice and shiny like this when done (MC3.1 upper photo, MC2/3 lower photo shown with bearing installed)

Headset Cups

Step 17: Install crown race. Best way to do this is with a pipe that fits over the fork steerer tube.

Headset Cups
Headset Cups

Step 18: Install bearing on fork. Install fork into frame. Should look like this. Lowww stack height (MC3.1 top, MC2/3 bottom)

Headset Cups
Headset Cups

Step 19: Install upper bearing and top cover/compression ring. Top bearing cover should just touch the top of the headtube providing a watertight seal. You can apply some grease on the cover lip, or just leave it dry. Aluminum bearing covers will have about a 0.5 mm gap.

Headset Cups

Step 20: Tighten down aheadset top cap so it’s just snug. Fork should turn freely and both upper and lower bearing cups should sit square in the frame (no misalignment).

Headset Cups
Headset Cups

Step 21: Ready to ride. Enjoy your transformed Klein with its new fork and smoooth heaset.

-David

Klein MC3.1 Airhead Conversion Kit For Sale

My first production batch of Klein Airheadset MC3.1 to Chris King 1 1/8″ is finished! There are 12 sets pictured, one is now on my Mantra, which leaves 11 up for grabs. I’ll be contacting people in the forums if they would like a set in the order that they posted. Post in the forums or leave a comment here for more information.

Forum Link

Thumbnail Gallery of cups installed in my Carbon Mantra frame

Airhead Chris King bearing conversion cups

Headset Cups

Fresh Batch of 12 headset cups

-David

The Mac Address Forums

Have a Klein Mantra, Q-Pro, or other Klein?

Looking on how to convert your Airheadset or service your Stratos Helix shock?

Have a Subaru EA82, Saturn LL0 Twin Cam, or Toyota 4AGE?

Have a standalone ECU and want to discuss tuning … particularly with individual throttles?

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Head over to the new forums and start talking about it!

The Mac Address Forums

-David