Dropout Failure Experiements, and a call for Fork Donations

[Zesty Bonanza]

When the Cannondale Headshok was tested, did you have to file the drop outs so the axle will fit? I have a headshok and it seems to fit only 9mm axles whereas the electric hub/wheel that I bought uses a 10mm axle. I am thinking of filing down the drop out so my wheel can fit in it and I will use both rev 2 and rev 3 torque arms.

[Hugues]

Good analysis thanks.

Am I right to say that with regenerative braking the problem could get a little worst as the torque applied would be in the other direction ?

thanks

Hugues

[justin_le]

When the Cannondale Headshok was tested, did you have to file the drop outs so the axle will fit?

Correct. If any of the dropouts were less than 10mm then they were filed accordingly until the axle would just fit. This is pretty common with hub motor installations on front forks. Standard front axles are 9mm or 3/8" diameter, and the normal fork opening is 9.8-10.0 mm for a generous fit, but some are done tighter.

Justin

[John in CR]

Good analysis thanks.

Am I right to say that with regenerative braking the problem could get a little worst as the torque applied would be in the other direction ?

thanks

Hugues

Yes, the extra issue with regen isn't the magnitude of the force, but the repeated forces trying to spin that axle first one direction on acceleration and the other during regen. Over time it loosens things up, so check the axle nuts even more frequently, and be alert for an audible "tick" when you hit the ebrake, which indicates that axle is starting to move in the dropout.