OK, what have I gotten myself into?

I'm a newbie when it comes to C&V. I bought an old Gitane. I posted a question about the bottom bracket here before, you may remember, and got some helpful advice. I overhauled the bottom bracket, reinstalled the old cranks and was relatively happy until I noticed that it had a huge wobble.

I thought maybe the chainring was bent, but now I'm thinking I probably just didn't tighten the bolts enough. In any event, I bought a shiny new crankset without thinking at all about which square taper standard I had or needed.

So today I pulled the old crank, put the new one on and, lo and behold, it doesn't even come close to fitting.

Naturally, the next thing I did was to go read Sheldon Brown's article about square taper standards. Surprisingly, it didn't really leave me with a sense of understanding. The new crank doesn't come as close to fitting as Sheldon's article suggests it should.

Here are some pictures.

The spindle:



With the old crank sitting on it:



The top view of the new crank placed on:



That's not going to give me a good chainline.

The front view of the new crank:



You can't really see it well in that last picture, but the crank doesn't go on far enough to put the nut on the end of the spindle, so there's not even a question as to whether this could be forced on with enough tightening (though that seems like a bad idea anyway).

The scant documentation I've been able to find on the new crankset (Origin8 Pro Pulsion) says it needs JIS, but if so then what the heck do I have now? I thought JIS was the bigger one.

So, what do I do about this? Can I get a new spindle that will fit nicely in this bottom bracket? If so, what kind and where can I buy one? Or do I need to just put the old crank back on and wait for Velo Orange's French-threaded bottom brackets to come in?

Some should have a longer answer for you soon but as a quick respone, your bottom bracket is not a regular one that will work with the new crank.

I can't totally tell from the picture, and I'm not an expert, but you may have a ISO square-taper spindle vs. your JIS crank. But, your original crank is stamped with SR, so I would presume it would be JIS (SR is Japanese). https://www.sheldonbrown.com/bbsize.html#square

That looks like a case of a 3 degree spindle being mated with a 2 degree crankset. The identification on the spindle will tell us for sure.

I don't believe there's any identification at all on the spindle. Here it is out of the bottom bracket.



The crank is a SunTour of some sort. This is on a 1976 or 1977 Gitane Gypsy Sport.

That's what is called a Maxy style spindle. Typically, there is an numeric-alpha designation ( .e. 3F, 3H, 3K, 3S. etc) on the center section. They're quite common and inexpensive.

You're right. It says "52 3K" and then some mark I don't recognize (probably a Japanese character).

Is this Maxy style spindle not actually JIS? Did it come out before the JIS standard and that's why the spindle won't work with the modern JIS crankset OP purchased?

You just need a much shorter length spindle. You'll need to do some measuring and calculating
1. Measure the chainline you have now with the crank placed on the old spindle.
2. Remove the spindle and measure the overall length not including the threaded portion.
3. Measure the difference between the right and the left spindle lengths "outside" of the bearing flanges

After you have all that get back to us.

I don't think spindle length will make much difference here, because the new crank doesn't go on far enough for the threads to stick out enough to even start putting the nut on, and I'm using spacers in the back, so nearly any chainline will work for me.

Anyway, here's this, for what it's worth.

Well, there's your problem, as I suspected it is a 3 degree taper spindle. You'll have to visit your LBS and get a 2 degree taper spindle. BTW, the 52 refers to the distance between the races and indicates it's indtended for a 68mm shell width.

Unfortunately, getting a correct chainline with a new crankset and spindle can be a bit of trial and error. However, you should be able to get close on the first try. Put the old crankset on the spindle (not installed in the frame) and place a straight edge across the back of the inner chainring. Now measure from the straight edge to a datum point on the spindle, such as the inside edge of the bearing seat. Once you know this measurement, take your new crankset down to the LBS and try spindles until you find one closest to this measurement.

Not a problem. For now at least, I'm using a single cog on a freehub with spacers in the back, so any old chainline will do.

Anyway, as a direct result of your query about the spindle markings and the subsequent disassembly, I got a good look at the inside of the fixed side threads and discovered that this thing isn't French threaded as I had previously assumed.

As seen in the other thread I started parallel to this one, it's looking like it's English threaded, which obviously will make my life much easier.



Thanks to everyone who kindly offered their help and insights.

T-Mar - How can you tell it is a 3 degree taper? The "3K" designation is one of the sizes for JIS spindles shown on Sheldon's BB interchangibilty page, (https://www.sheldonbrown.com/bbsize.html#square)but he does not reference anything other than 2 degree spindles there?!?!

I have this same question. Although, sometimes you can tell by looking at how "rounded" the angles on the square-taper is. Or, its "stubbiness"