[Dafni]

Thanks for the input, Serum.

The 9918 has 15° timing, but this can be changed. Also, you can set it to Autotiming (whatever that means).

I think 110°C is a bit high. The Neodymium alloy undergoes a phase-transition at around 120°C, which may lead to instant loss of the magnetism. But I think this is a rather smooth transition, where the magnetism just fades over time. But theoretically you could kill the magnetsim by heat within a few seconds. I don't know the actual temp, though.
However, on our motors, I would say the lower the better, and I trust the guys who say everything below 80° is pretty save.

I will try the 18t and see what temps I get. I will also add a oneway to the fron end. This should reduce some brake stress on the system. Let's see. I just want a setup where I can run pack after pack without worries.