I've ridden a BBS02 for seven years off road (and three more by my son) and three with a second one with neither maintenance nor problems and I'd feel just as confident with a Bosch or Yamaha system. However, Fazua, Mahle or RM aren't in my future. JMO! I appreciate that Bafang didn't change the BBS02 for about 10 years (although I think it's been removed from their inventory) and almost all parts are available to repair it even though it was not necessary, and the fact that the battery is removable so the bike is easier to put on a rack.