If you ever hear an urban legend about a kid who cut off his nose with garden shears, that is categorically true - I went to junior high with that kid. At the time I thought it was hilarious. Still sorta do...
And much like the garden shears kid, every once in a while something that people thought was an urban legend turns out to be true.
A month or so ago, I saw this on eBay:
It's a 571/2 hub...ED? I had previously seen hubs marked 571/2, and 571/2 HG - HG being, of course, hubs with Shimano's cassette splines, instead of the Mavic proprietary type. This particular hub has a serial indicating its from 1995.
Through a roundabout series of purchases and ultimately a trade with Harry, I ended up with the 571/2 ED. When I got it out of the box and took a look, though, I was dismayed to see the Mavic spline pattern on the cassette body.
It's worth noting that the Mavic proprietary cassette came in 2 flavors. With the 571 hub, the outermost cog was threaded, much like Shimano's Ultraglide (UG) cassette. With the 571/2, Mavic went to a lockring setup, like Hyperglide (HG). If you're ever looking for Mavic cassettes, be aware of the difference. The spline patterns are the same, however, so you can adapt a 571 cassette to work on a 571/2 if you can source a correct 8th cog and lockring
For a long time, I had believed that Mavic made an Exa Drive version of the 571/2. So once I saw the hub marked ED, I decided to consult my primary materials to see if it was true. Turns out, I couldn't find any evidence that it existed. Chuck Schmidt over at Velo-Retro sells a phenomenal collection of Mavic catalog reprints, and it wasn't in there. I checked magazines that had information about the 571/2. I read about ZMS. I read about Mektronic. They all mentioned that HG was available, but no mention of ED. Maybe the early Cosmic wheel set, that used the same cassette mechanism as the 571? No dice.
Moving right along. I thought I had captured my Moby Dick, but it turned out I had a normal Mavic splined 571/2 hub, with a weird ED marking on the model band. Facing facts, I came to the conclusion that I was wrong - no Exa Drive 571. Just what was this ED marking though? Electronic Drive, marking it as part of the Mektronic group? That didn't sit well with me, especially since Mektronic was designed to work with Shimano (and Mavic) cassette spacing.
So it stood. Until I spied something weird in an eBay listing from France.
The thing that piqued my curiosity was that, based on what I would see, the splines looked weird for Shimano. They had a trapezoidal quality to them, and based on wishful thinking, I counted 8 splines. Shimano HG has 9.
Sure enough, when I received it, my suspicions were proven correct. 8 splines, undercut a little. EXA DRIVE.
Seperated at birth?
The Mavic sponsored GAN team sometimes rode an odd combination of components in 1993 and 1994. Mavic brakes, cranks, front derailleurs and wheels, with Ergopower brifters and a Record rear derailleur. Were they using the 571 or 571/2 rear hub when they rode that setup? There are a few ways to pull that off - respacing a Mavic or Shimano cassette being the easiest other than just using a Record rear hub. Is it possible they were using an Exa-Drive body like the one I now have?
I can't say for sure this is de facto evidence that Mavic produced an Exa-Drive 571/2 for the public, and marked it as a 571/2 ED - though I certainly think they did. But if anyone tells you that either the pruning shears story OR the existence of a Campagnolo body for the 571/2 is total bullshit, send them my way.