Hello, I know that this has been covered quite a bit in the past but I need a refresher. I just purchased an older Klein Quantum on eBay, size 57. It is one of the earlier ones with the press fit bearings and square taper bottom bracket axles.

I will measure the axle width and check the feel of the bearings when I get it. I suspect that the square taper axle will be for a double crank. I really most likely will want a fresh start with different options.

My first task will be to knock out the press-fit bottom bracket bearings. I know that Klein dealers used a proprietary tool for this but I thought that there might be new versions of this tool available now that so many current bikes are using the pressfit bottom brackets. I'm going to check the Wheels Manufacturing site for a sealed bearing removal kit. I already have the Wheels Manufacturing deluxe bottom bracket press with different size drifts that hopefully would work to press in new bearings.

Yes, there are old threads on this subject but thanks to the expire dates on photobucket, or other photo hosting sites, the detailed photos of the procedure are long gone.

I would like to run a Shimano 24 mm Hollowtech compact crankset with this bottom bracket. I would love to hear about it if anyone has done this conversion successfully.

Thanks for any help !

https://www.mtb-kataloge.de/Bikekatal..._manuals96.pdf

Thank you!! This is a great reference!!

If you want to go to Hollowtech II and outboard bearings, Phil Wood make a pressed in outboard bearing set up for Kleins.

Phil Wood & Co.

Phil Wood also sells Klein compatible spindles in a variety of lengths and both ISO and JIS tapers. (Even Ti spindles.) There is nothing wrong with a quality square taper crank.


While they don't explicitly state this will work, chances are it will because the Klein shell inner diameter is 35mm, just like the French shells it is designed to work in. It is self expanding and offers a variety of JIS spindle lengths.

https://velo-orange.com/collections/...ottom-brackets


The Klein system is simple, offers control of spindle centering and is very tough. It is also pretty cheap to replace just the bearings. It is not difficult to perform removal and installation with ad hoc wood blocks, crank bolts and a mallet. The old bearings can also serve to press in the new ones.

If you want to go to Hollowtech II and outboard bearings, Phil Wood make a pressed in outboard bearing set up for Kleins.

Phil Wood & Co.

Phil Wood also sells Klein compatible spindles in a variety of lengths and both ISO and JIS tapers. (Even Ti spindles.) There is nothing wrong with a quality square taper crank.

this looks like a great solution, but it appears as if they are sold out. I'm going to check and see if Hope makes a press fit in the same size.

A shop mech near me somehow got the BB out and threaded the shell. No idea how, but she looked at my Klein and said "I can do it." I was looking to go Hollowtech II, as well. Actually, BB30 would be just as fun.

Any idea how BB30 translates to the Klein dimension?

It doesn't. The Klein shell is 35mm in diameter, and BB30 is 42mm.

Robbie's shop either threaded the shell for Italian thread (36mm x 24tpi) and added 1mm spacers under each cup, or they bored the Klein bb shell out a few mm wider and pressed in an English sleeve. The first would be easier, and Shimano still makes Italian Hollowtech BBs. Install with loctite since the inner diameter will be .1mm undersized.

Italian threads are also convenient because you can just turn them all the way through the shell.


Edit: Early Klein road bikes used 68mm shells, later 94-96 BB shells were 72mm. If it is the later version it would have to be faced down 1mm per side rather than require spacers.

If that's what you want, call them. One of their distributors might have them in stock, or they might have more in production soon.

This is probably what I will do. My frame is not going to be delivered until January 4th. When I get it, you know I'll be inspecting it and checking dimensions with my metric dial calipers.

Ask them about the 68 vs 72mm shell. The instruction PDF link lists that dimension on page 22.

Well the frame was delivered the other day. Quite rigid, not particularly light by modern standards but very impressive!

I spoke with "Peter" in the machine shop at Phil Wood. They still had a few 35 mm press fit external bearing bottom brackets for Klein. I'm having my LBS (International Pro Bike Shop in Bellbrook, OH) order it for me. Peter was very encouraging about a worthy project. He advised me to have my mechanic call him with some of the specifics of the pressed in bottom bracket and he volunteered that they will make an extraction bushing for him for free. I'm really hoping that this happens!

I spent a cold weekend of being sick having a marathon of perusing archived Klein catalogs and it appears that this white Quantum is an '89 model. The white "Quantum" decal on the top tube has a unique font that looks 90's futuristic (think "Tron") with forward black slash marks in the background that are uniquely spaced. I looked on Ebay for replacement decals but have not found an exact match.

The rear triangle on this bike is a very stiff 126 mm. A perfect platform for some old school 6/7 speed tubulars. I have a high Flange Campy Nuovo Record set on Arc-n-Ciel rims or a cool set of Bullseye hubs with black flanges and gold centers laced to gold anodized Mavic "OR-10" tubular rims. I'll probably try both to see which I like better. The white with silver color scheme is really fresh but the white frame is so neutral that gold blingy parts might just jump to life as well. Tell me what you all think.

The pressed in square taper bottom bracket spindle on this frame is longer on the non-drive side than it is on the drive side. My interpretation of this is that perhaps someone tried to extract it and got the bb axle to shift to the non-drive side. Not sure.

https://www.flickr.com/gp/157207353@N04/V02YA1

Just a test as I continue to try to use Flicker to upload photos...

It was probably for a triple that used an asymmetric spindle.

Sounds like you have the 68mm BB shell.

Just measured the bottom bracket shell @ 76.0 mm

and the bb spindle @ 119.3mm.

The dudes at Phil Wood are awesome. I love that they still make a BB solution for nearly every bike on the planet.

Yeah, if this quantum gets to live on with a current Shimano 24 mm external bearing bottom bracket...I'm going to be seriously stoked! It will be worth the money.

Once it is installed I will get to ponder which modern Shimano crank will work best for this application. I have several nice ones - compact or conventional doubles, and several triples that I can deploy. Fun times!

Probably a triple (either Ultegra 6603 or 6703) is what I will go with due to the 126 mm 7speed spacing. This way I can use a narrow racing 7 cluster (with 12 - 23 for example) and this combined with a 52/39/30 in front I'll still have a good spread.

76********** You had better let the Phil Woods guys know that it is that wide. That's really odd.

Well I did discuss it with my mechanic, Roger. He scribbled down a few notes for when he calls. We even discussed the wider width bottom bracket shell and how that might influence the dimensions of the external bearings. He did not seem to feel that it would be a big issue if designed correctly. But yeah, I hear what you're saying. If the Phil external 35 mm "Klein" press-in Shimano bottom bracket is based on the English 68 mm bottom bracket shell standard - then I'm going to have a real headache misfit on my hands.

I can't find any reference to a 76mm shell. The only thing that occurs to me is that the total width of Klein BB is the same as the total width of a loose ball BB on the outside of the cups. (68+4+4)

Anyway, I'll be curious to hear with the Phil Wood people think.

Me too, thanks for your interest. I will definitely update this thread as the project evolves.

Here is a link to my metric dial caliper verifying that the bottom bracket shell is indeed - 76mm!

https://www.flickr.com/gp/157207353@N04/41UW89

Maybe it is just the angle of the photo, but the BB shell looks wider on the drive side. Could you measure from the center of the downtube?

the bike drive side is angled away. I just measured it and it is symmetrical. Interesting - it is 3" wide exactly and the distance to the midpoint is 1.5" from each face of the bb shell.

Thanks to everyone who responded here, I am in the process of figuring out my Klein MTB (possibly a Pinnacle from the early 90s) I am probably going to keep it pretty stock but like the idea of a external crank in case I want to change things up. I knew and had planned to order Phil bearings for it but didn't think about them doing a external BB however it makes sense since they do one for Swiss threads.