1996 Klein Quantum Pro; changing from an MC2 stem project.

[The_Don]

This is my Klein Quantum Pro. I have had it a year and want to change to a modern short drop and reach handle bar.

Also, I find a little bit too stretched on it (it's a 57cm frame and I usually ride a 56cm) so I want to change the stem to a 90mm from the current 100mm.

I did a lot of searching and heard that Klein did make a shim to fit 1 1/8th stems, but finding one after so long is proving impossible. I also saw that Reset Racing started making a shim. But after 2 months of emails, I have had no response.

So I did some calculations and figured I need to go from 1 1/16" = 26.9875mm to 1 1/8" = 28.575mm.

A difference of 1.5875mm so the shim will need to be 0.79375mm or 0.8mm.

I found this Cane Creek seat post shim that goes from 27.2 to 28.6mm, which is a diameter change of 1.4mm or 0.7mm shim thickness. As it is so close to the correct dimensions, it should slip on snugly and mate the 1 1/8th inch stem nicely to the Klein steerer. Hopefully the 0.1mm will be fine when the stem is tightened. I am planning to trim it down to size as it is surely too long.

I also bought the new stem, a nice 3T Arx Pro that I have been seeing a lot of on the weight weenies forum. It is lightweight, looks nice and is pretty cheap, but comes in the size I want, 90mm with -17degree angle to have a parallel stem like I currently have.

Finally, I bought some new bars, I would love to have gone for the 3T Carbon Ergonova, but budgets are tight at the moment, so i opted for a Deda RHM02 at 1/10th the cost, which have nearly identical shape and nicely flattened ergo tops at just 50g added weight. Also seem much stiffer than my current 25.6mm bars which should be named, sir flex-a-lot.

And to top it all off, a cheap carbon top cap with 1 inch star nut.

I am planning to pick up replacement carbon spacers once I have completed the operation, as I am not a fan of the chunky plastic spacers the MC2 has. I can give or auction away the unwanted old MC2 parts as I hear there is demand for them.

I have nearly everything I need for this little project accept for one vital thing. The MC2 tool. Luckily, one is flying to Tokyo from New York at this very moment. I posted on the Klein owners group in Facebook and someone is being kind enough to lend it to me. Shipping came to $5.60!!!

I will document the process to help future owners escape the evil that is the MC2 stem. It's a great design, but since it is no longer produced, when having to change the stem, it's a great proprietary problem.

 

[i-am-iron-man]

As much as you don't like the MC2 stem ...

... don't sell it!!! As you point out, very hard to replace, and you'll be filled with remorse if you ever have a change of heart or decide to sell the bike. Klein buyers wouldl almost certainly see the loss of the bike's original stem as a bad thing.

 

[The_Don]

Step 1

So the tool arrived in the post! Thanks Mark from New York for lending it to me!

Step 1, Remove the MC2 stem.

This was pretty easy, put tool on and turn anti-clockwise. The silver top part spins, but is connected to the stem itself.

When the stem is taken off, the collet will still be on the steerer tube, it was greasy, so I used a tissue when pulling it off.

Now the Klein Spacers can be removed. Exposing the entire tube.

Step 2, Make the shim.

Again, a simple task, I put the shim over the steerer and used some tape to mark where i want to cut.

I then used a crappy hack saw and got a surprisingly straight cut. I then filed the bur off and removed any imperfections with the file also.

Pretty nice fit.

Step 3, Put the shim and new stem on.

Yawn... This is too easy, but the juicy fun part. As the Klein doesn't use a top cap to put pressure on the head set bearings, I can put the stem where I want on the stem and not use any spacers (but I will get some later).

Shim could do with 0.2mm more thickness I think, but it's on very solid, so I guess it is within tolerance.

Step 4, Prehensile Top cap install.

This is really just to stop water getting into the steerer and look nice. I was thinking of an expander plug, but star nuts are so cheap. I got 1 inch and 1 1/8th inch star nuts and checked which works better. The 1 inch one looks the best fit, so pop it in and hammer away!

I then measured the amount of empty un-spacered steerer and bought some carbon 1 1/8th spacers to fit, with a flared one at the bottom.

 

[Lysander]

Sorted!!

I changed the forks on my Q to EC90s (standard stronglight h/set, so no hassles there, just changed it for a bbb aheadset)......luckily found the ITM Millenium stem which came with a shim for 1" steerers.

Them inline gear indicators ye've got?

 

[The_Don]

Yeah, the right side is an in-line gear indicator. The left side is a barrel adjuster for fine tuning the front derailer.

Here are some nice photos I took to celebrate a job well done after today's post rapture ride this morning.

 

[The_Don]

Update.

I decided to see if I could do something about the 0.2mm shim difference as the spacers had a slight bit of wiggle room.

I cut an aluminum can to make an extra single layer shim. It is now a perfect fit.

It is very tight and I think the double layer shim will hold solid.

 

[milko]

Oh come on! Look at that pic with the city in the background, it could not get much more perfect it is like you live in the future (as envisioned in the 80s)!!

 

[The_Don]

Oh come on! Look at that pic with the city in the background, it could not get much more perfect it is like you live in the future (as envisioned in the 80s)!!

If you like that, you might like the view from my old apartment. And YES, when I ride around Tokyo at night, I do listen to the Tron soundtrack!

I'm going to have to go out and take more photos once the rainy season finishes!

 

[INDECS]

Wow, nice Klein and great pics!

That is Roppongi, right?

 

[The_Don]

Wow, nice Klein and great pics!

That is Roppongi, right?

No, sorry, it's Tamachi.

I don't like Roppongi. Shibuya is much better!