Fixing Useless Mavic Ellipse axles – UPDATE – 20 axles manufactured and ready for dispatch.
I got so fed up after snapping the rear axle on the Ellipse, and then destroying the bearing preloader taking it off, that I decided to design my own axle. Mavic specify 40Nm
on their website for the M9x1 wheelnuts. This is a totally ridiculous torque, giving over two tons of axial preload (21kN). No wonder it snapped where Mavic
brilliantly sunk inside an internal hex inside where the nut thread sits…another side effect is seen on the other side of the original axle (which is soft as cheese) the tapered
spacer sits right on the M12x0.75mm thread where the bearing preload adjuster threads on. The useless steel then mushrooms when you tighten the axle nuts, you will not notice
this has happened until you try to remove the preload ring ! It will then come off about 4 turns and stick fast, this is because the thread on the axle is flared out….cant believe
I was stupid enough to follow their instructions without stopping and thinking rationally about it.
My axle is longer so that even with really thick dropouts you still get complete thread engagement, with some threads to spare. It doesnt have an internal hex, but this doesnt
matter as its easily remedied by locking two M9 nuts together on one end to stop rotation for setting preload or dissasembly etc.
So I will be using 18Nm from now on, which will give me 9.4kN preload. – this puts about 350MPa onto the area between the steel spacer and the end of the M12x0.75mm thread.
Although on my axles the end threads are removed so that even if it did get overtightened the threads wont flare out and jam on the preload disc.
Next step is a new front axle, might go for Titanium as the steel one above is hopelessly over engineered considering the minimum size constraints of fitting into the existing
hubs and dropouts. I went for AISI PH13-8Mo, so even after necking down the middle to 7.2mm diameter it will still require over 5 tons to break it. Unlike the original which is both of useless design
and made of what I think to be equivalent to recycled tins of baked beans. Maybe I will get it into a tensile tester just for fun to see how cheap Mavic went on the material spec.
Good idea, making the axle able to be locked while tigtening….bad idea…put the hex inside where the nut goes on.
Seriously Mavic….this is really useless design – especially if you follow your instructions to use 40Nm !