Raleigh71

Tell me if I have this right:

You can get axles in different lengths, my supposition is:

What varies is the DRIVE SIDE length and the non-drive side length is the same?

HillRider

No. Both drive side and non-drive side length can vary. Symmetrical spindles grow both side equally as they get longer. Non-symmetrical spindle usually make the drive side longer as the overall length increases.

techsensei

This page lists the most common axle sizes: https://www.starcyclespares.co.uk/bik...gths-229-p.asp

cny-bikeman

The spindle needs to meet three criteria -
1. A good chainline with the cassette or freewheel
2. Clearance between the smallest chainwheel and the chainstay.
3. approximately even distance of the two crank arms from the center of the frame.

It does so in combination with the design of the crank, and more recent cranks require a shorter right side to put the crank in the same relative position. So there's no one rule for what happens with increasing spindle length nor for what spindle length fits a certain bike.

Looigi

Where the rings are WRT the DS end of the spindle varies too. The spider can have more or less "dish" or bulge. For example, BB30 is pretty narrow, so a BB30 specific crankset often has a relative flat spider across its hub. A BB90 or GXP is much wider so the spider bulges outward at the hub to accommodate the greater bearing spacing.

Where the rings are WRT to the centerline of the bike is the same in both cases, as this determines the chain line.

Bill Kapaun

But can you find one in the length you need?
The "wide" assortment of available spindles is getting pretty narrow.

Raleigh71

Thanks for the info.

I've got a bike with a trashed Shimao Exage 300 crank, and the chain line measures 43.5 or so, a far sight from the 50 mm chainlines I see listed for the common Alivio replacements.

The recommended BB casette is UN-26 that comes in multiple different lengths.

My solution was to very carefully measure the geometry on the old crank including the distance to the chainstay from the small chainring, and also measure the lengths of the various segments of the old spindle, and see how that all changes when I mount the new crank on the OLD bottom bracket.

Based on that I'd get a crank spindle that would bring the chainline in a bit, closer to the 43.5 mm it is now and not have the small chainring hit the chainstay.

Also I don't have much more lateral throw on the front derailleur.

Any problem with the above?

Bill Kapaun

Chances are that bike had 126mm drop out spacing.
Going to 135mmwould add 4.5mm to the chain line.

Edit-
It looks like the Exage 300 was from the 1990-1992 era, so drop out spacing "could" be pretty variable.

Raleigh71

Actually I rebuilt the rear hub a couple years ago, and there's no more clearance to move the cluster away from the center line so I'm pretty sure I'm going to have to get the chain line right at the crank end.

Thanks.

Bill Kapaun

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