Just need some clarity.
1. can they take punishment? Like out of the seat mashing uphill in a hurry. Are they durable?
2. What's with shifting? Can I shift the gear hub on the fly? (while pedaling)
3. Are there any other limitations like gear range or anything else?
4. What is the failure mode. Do they fail to a predetermined gear or just rotate freely?
5. Maintenance, anything I should know?