RandolphCarter

Hi all.

I have an early 90s Raleigh Eclipse hybrid bike that I'm converting to single speed.

The wheelset I want to use has a free/fixed flip flop hub and the rear dropout spacing is 135mm. From the inner face of the drive side rear dropout to the center line of the teeth on the freewheel is 29mm.

(135 / 2) - 29 = 38.5mm chainline, according to Sheldon Brown's guide.


I'd really like to use the late 70s Shimano 600 Arabesque cranks that have been kicking around in my parts bin for 20 years or so.

So how do I figure out which spindle length bottom bracket to get for those cranks?

EDIT: The frame has a 68mm English threaded bottom bracket shell, if that makes a difference. I'm assuming the cranks are JIS taper.

Rolla

I *think* the Arabesque front chainline was 42mm, but I don't know what spindle length was stock. Maybe see if anyone in the Classic and Vintage subforum happens to know.

If you have a spare bottom bracket sitting around, you can install it along with the cranks and measure whatever front chainline results; using that as a baseline, get a BB with a spindle length that gives you 38.5mm. It doesn't have to be exact, and you can adjust it further by mounting the chainring on either the inside or the outside of the spider. Regardless, you also need to see if you have enough chainstay clearance for the chainring you use.

Hope this helps.

RandolphCarter

It does, thanks.

JohnDThompson 

AFAIK, the 600 series cranks were never offered in a single-ring configuration, so you'll need to cobble up a solution. Do you have the original bottom that went with the 600 crank? If so, the easiest fix is to use the original BB and run a single ring on the inner mounting shelf of the crank; that usually gives an acceptable chainline. Dura-Ace track cranks of that era used a 107mm spindle, but that may make the inner mounting shelf too close to the chainstay, unless you file it off. In any case, you may need to play around with various spindles to find one that works best. Having a bike co-op or friendly LBS wih a bucket of used spindles is helpful.

RandolphCarter

No, the original 600 spindle is long gone. They were on a Ross touring bike, set up as a triple. I do still have the inner 39T chainring that I hoped to use.

I'm afraid if I pop in to the co-op to paw through spindles I'll return without the spindle i need but with several additional project bikes...

I'll try wooden dowels cut to various lengths to approximate what size spindle I'll need.

Thanks!

EDIT:

Or, an old axle and some nuts.