I need a crankshaft or axle (I don't know what it's called, the shaft that the cranks are attached to.) for my 1977 Super Mirage. I found the cranks and chainwheels on Ebay. The seller didn't mention the shaft, so I emailed him/her and asked if one was available.
The seller has 100% positive feedback, but hasn't replied to two emails.
I guess I have to assume that I'm not going to get the courtesy of a reply, and that one is not available?

It's a holiday weekend, when did you email?

"Spindle"

Bottom bracket?

The 21st and the 25th.

Axle=spindle
Bottom bracket would include axle, cones, cups, bearings. I think.

I appreciate the lesson on the terminology. Spindle it is. I'm a car guy. It would be a "crankshaft" to me! "Bottom bracket" sounds like some real old school terminology there.
Too bad I can't get the seller to contact me. All I'm trying to do is give him/her money. 8-)

I said bottom bracket because I figured you need the cups and bearings too. I like Shimano UN51 sealed cartridge BB. You might want to get one of those if your crank is square taper.

In two years you didn't ...

a) learn some bicycle terminology
b) fix your bicycle?
https://www.bikeforums.net/showthread...t=#post8296892

And you're upset that someone didn't respond to your email in 1 week?

I fixed it for you.

It's ebay.

That is all.

Before you order anything you need to know what you are ordering. Things like what length of spindle, is the spindle symetrical or non, what threading do you need on the cups, what is the taper for the crank you 'd like to use?

Wow, thanks dedhed. I was wondering about dimensions like you mention. I guess I'm going to need a parts bike to get a match.

Start with the chainline that you want to achieve. Do a google search on "chainline" and you will learn how to measure, and how to determine your optimum.

Next, determine whether your Motobecane frame is of French or Asian manufacture. This will be evidenced by the thread type within your bottom bracket shell.

Take the bike to a qualified local bike shop or coop with trained volunteers, and see if you (they) can find a proper bottom bracket bearing/cone/lockring/spindle setup for your bottom bracket. Best to use loose parts rather than a cartridge bearing, so that you can change out spindle lengths as necessary...

Next comes the empirical part, the spindle length will determine the chainline for your crankset. Doing a search on your particular crankset [may] yield discussions by users who have achieved certain chainline using various spindle lengths. It may not.

If not, you'll need to use trial and error, mounting your drive side crank to a mounted spindle and measuring the resulting chainline. Adjust spindle length to suit your objective - swap out spindles to get the correct length.

If the whole setup is French...good luck finding compatible threaded parts.
If Japanese - you'll have no problems - the coop or LBS will have all you need in their take-off parts bin. Get new bearings, though, and use good quality grease.

PG

Yikes! Thank you for your in-depth post, Phil. I like this bike, but I'm not going through all of that. If I find a parts bike, I will be lucky. But that's all this is worth to me, time and effort -wise.