Monday, August 20, 2012

Mavic's first cassette hub - the 570

Mavic's first "successful" cassette hub was the often talked about (on here at least) 571. The 571's design was similar to the other hubs of the era - a driver with a spline pattern, cogs held in place by either a threaded outermost cost (571) or a lockring (571/2).

The 571 wasn't Mavic's first cassette hub, however. That distinction goes to the MRL 570 hub. Also known as the Z-Hub, the 570 was an interesting, albeit quirky French take on the cassette.

Where a modern cassette would have its splines, the 570 has threads - what might be called by some an Acme thread, they're similar to the threading often seen on the lead screw of a lathe. Mavic made a number of claims about design that were of specious validity. The design of the 570 (and the 571, 575 and 577, for that matter) allowed the cassette driver to be removed from the hub using only hex wrenches. This, Mavic claimed, would allow you to have drivers loaded with cogs, ready to go for quick changes of your gear ratios. Aside from the fact that spare drivers were non-existent, one attractive quality of a cassette is the ease with which you can swap cogs - having a pre-populated body doesn't sound all that attractive. The 570 also had its issues. The driver was prone to splitting - perhaps it was machined rather than forged, and the loads it sees either from cogs snugging themselves down too far or through torque could cause it to crack perpendicular to the threads.

It was also possible for the cogs to overtighten, making their removal a chore - and given that they all threaded on, it was easy to land in a situation where you needed to wrestle all 7 cogs off by hand. Fortunately there was a tool to hold the cassette mechanism in place, lest that 7th cog stay on there forever...

A cheap hub this was not. With a retail of close to $400 with a front hub and alloy cassette, it's no surprise there aren't many to be found.

The 570 was available for a year or 2 before it was replaced by the much more refined 571.


Anonymous said...

Always appreciate your posts. Keep them coming.L.

pinkfairy said...

I just checked to see if the cassette's threading is the same as Maillard Helicomatic. It is not.

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