So I've been looking at Stronglight cranksets on E-bay off and I'm wondering if there are big differences between a French square taper crank and something like a Sugino SuperMaxy?

I've had a few bikes pass through the garage with Stronglight sets on them but never had the chance to try one on a different brand spindle.

Can I run a Stronglight crankset on a Japanese spindle?

I'm sure someone here knows the answer.

French spindles have ISO tapers while Japanese spindles have JIS tapers. The tapers are somewhat compatible because they share the same taper angle, but differ in the starting and ending taper widths. A JIS crank will slide farther than an ISO crank onto an ISO spindle, and conversely an ISO crank will slide less than a JIS crank onto a JIS spindle. Lots of people interchange them, but it can cause problems. For example, seating an ISO crank onto a JIS spindle will result in less contact area along the tapers, but people have raced with this type of configuration and it doesn't lead to catastrophic failure. It may reduce the life of the taper, however.

Sheldon Brown provided a good explanation of this.

I have a set of ISO cranks installed on a JIS spindle, and it works just fine. I estimated that a 115mm JIS spindle would give me the same chainline as a 120mm ISO spindle, and that worked out to be the case.

There are two standards for square tapers: JIS [Japanese] and ISO. The main difference between them is that with JIS the square part is 12.73 millimeter at the beginning, and with ISO it is 12.6 *. So a Shimano crank simply won't shove down far enough on a European taper. And a Stronglight will shove down too far on a JIS square taper.

Still, sometimes that is just what you want.

* some sources say 12.63/12.5
** yes, there have been more sizes in use.

Two standards, and one or two non-standard designs, Ofmega/Avocet being one.

Isn't there a distinction in taper fit for modern Stronglight and early ones, like '50s/60s 49D's?

What you really have to watch out for with insertion is taht the taper end will not bottom on the bolt when it's torqued, and that the crank arm is not squished onto the taper base when torqued. The former situation results in the taper not stretching the crank arm properly - the arm will rattle on the taper, and eventually fail the crank after enough cycles of pedaling force. The latter situation will probably overstress the crank arm or the drive side crank. It would also be a failure.

Great info guys, thanks!

Now if I can just get the funds together for the Stronglight set I want. The two I really like are the 49D and the 63.

I have no idea what the story is on these, but someone is apparently
making and marketing cranks under the Stronglight brand name again.


https://xxcycle.com/ironlight-titane,,en.php



Does anyone else know more about what is going on
with these and whether it means I'll finally be able to
once again buy Stronglight crank caps without paying
ten bucks each for them?

Is this remotely related to the old Stronglight, or is it
just another company that bought a brand name like
Schwinn?