On a lark I bought a very nice condition + reasonably priced + awesomely purple 1990 Klein Quantum online thinking I would make a few updates to it and would have a kick-arse ride come springtime. Unbeknownst to me, these early Kleins have an oddball bottom bracket design, i.e. a 119mm spindle running in press fit bearings in a 76mm wide shell . I remember lusting after a Klein back in the day and do not recall ever hearing about this quirk in any of the groups I rode with or shops I frequented. (Frankly, I find it hard to believe that someone as smart as Gary Klein thought this was a good idea.) I have done a lot of online searching about my options and know that I am stuck with what it is but I am wondering if the strange dimensions of the BB were taken into account in establishing the chainline of these bikes. The bike has a full 8-speed era Shimano 105 group and looking at the crank it looks like a normal crank and not some one-off freak to match the Klein's BB.I want to swap the 105 out for something with a 110mm BCD to run chainrings much less than 52/39 (age and locale make this a must-have for me and I do not want to go with some pizza sized cassette) but most of the affordable options call for spindle lengths of 110 - 113mm (or some proprietary taper design; I am looking at you Sugino). I worry that installing something like these is going to result in shifting and/or chain rub issues. A compact double is my first choice but if is not an option, I will go with the option of running 50/34 chainrings only on a suitable triple crankset that usually use 118mm spindles. Thank you for taking the time to read this and I am confident someone in C&V land will offer some sage insights about Kleins and their chainlines.

Press fit external bb Phil Wood bearings for Klein

​​​​​​https://www.google.com/search?q=klei...&bih=617&dpr=1

An early Klein to me would be 1975.
1990 is 15 years on.
Quantum was the budget frame, decent but odd.
I agree, go Phil Wood.

My ‘92 Klein Performance also had this BB. Worked great with Ritchey Logic (made by Sugino) triple cranks for me for over 38,000 miles, and my son is still using it with a Dura-Ace double crankset in a 9-speed setup, still going strong. Chainline was fine with both.

I’d imagine others in this community will know of other cranksets that use that spindle length or something close. A WTB post in the C&V For Sale sub-forum will probably turn up something that will fit your needs.

AFAIK, Sugino doesn’t use a proprietary taper, unless that’s what you consider JIS to be. Their cranks are widely used on all sorts of bikes. I’m using a Sugino AT (very popular among C&V-ers) on an SKF BB, and used their popular Sugino XD on son’s wife’s bike with a Shimano BB.

I believe Sugino 75s are ISO tapered but of course that isn’t proprietary either.

If you are OK with the current (square taper) bottom bracket axle, could you take some digital calipers & let us know what the BB axle width is (mm width)?

"AFAIK, Sugino doesn’t use a proprietary taper, unless that’s what you consider JIS to be." No, I do not consider JIS to be proprietary, however Sugino's online store lists a number of cranksets that use a "SG Mighty 4-Axle Taper" spindle; are you saying that this is only a fancy marketing name for JIS?

"An early Klein to me would be 1975." Please excuse my faux pas

Phil Wood External Bearing Kit - the problem with this is that there really aren't any modern crank axles that would span a 76mm BB shell + external bearings and where I live I am never going to find anyone who could face off the shell to a more normal 68mm

"If you are OK with the current (square taper) bottom bracket axle, could you take some digital calipers & let us know what the BB axle width is (mm width)?" it's a 119mm spindle running in press fit bearings in a 76mm wide shell

Where are you located? Most of us put that in some form in the User CP data. And try a WTB (Wanted To Buy) or ISO (In Search Of) in C&V Sales suggested previously.

Is there a bike co-op in your area, or a used bike emporium? Either would be a great source for a crankset that would meet your needs.

Probably no need to replace the existing BB spindle unless it’s no longer spinning smoothly. As noted earlier, that 119mm length works on a variety of earlier cranksets. Seems like only newer cranks use the shorter BB.

The OP appears to be correct in saying that some current Sugino cranks use a proprietary taper.

Some current Sugino cranksets use what Sugino calls a "SG Mighty taper". In particular, their Mighty Tour and Mighty Mignon cranks use this taper. From Sugino's website page for their current "Mighty Tour 901D" and "Mighty Mignon 901D" cranksets:

Photos at that page appear to show it similar to a square taper, but with concave-dished sides.

This taper may or may not be used on other current Sugino cranks. I didn't look in detail.

Edited to add: OP, I'd be very hesitant to purchase one of those cranks without first confirming that a new BB for your specific frame was available with that proprietary taper - because I'd guess the spindle you have now isn't compatible. And I'd also guess you'll need a spindle length different from what you have now.

My fairly early Performance sports a 6203 crank (110 bcd) on a 119 BB spindle.






Top

could you clarify though if you intend to continue running the same square taper crank? Are you wanting wider range gearing compared with the way it is now?

No, I want to replace the current 130mm bcd shimano 105 with a compact crankset with 110mm bcd. Yes, I am wanting to get lower gearing because it is hilly here and I am old. I don’t want to go with a large cassette.

-----


76mm shell width not unique to this application

also employed by Raleigh for models 20, Folder, Shopper



-----

I would think that finding a double (or triple) 110 bcd square taper crank that will work with your current axle should be doable. You could buy new or used. You could also try a 110/74 bcd triple crank and if you were lucky, there would be sufficient clearance for a granny ring.