I run my BBS02 with a 52 volt pack , I think I asked the seller to limit the amps to 24 it was a year ago , I think I saw 25 amps once briefly on a steep hill , road not dirt . I will be experimenting with different front chainrings . You can buy a few chainring adaptors with 104 BCD from many different places for the BBS02 and 130 BCD for larger chainrings on the BBSHD . the cheap ones from Aliexpress don't give a very good chain line , so with those you lose the lowest 2 or 3 cogs on the back . You can buy chainrings from different places that have some dish to them for both motors . I have a BBSHD on a different bike and run it on 12 lipo's ( 2 6s packs in series ) since they are the only packs that will fit on my full suspension frame with very little space in the middle of it . I prefer the BBSHD for all riding ( Flat and up steep mountains ) it is better and faster on 12s than the BBS02 on 14s . You can buy just the BBSHD motor and plug into it all the other sensors and display from your existing BBS02 , That is what I want to do in the future . From my experience with both motors you would be happier doing that . The BBS02 is a good little motor for people who live in flat areas though . I find that I don't feel like over volting either motor the BBS02 with a 48 chainring and the 52 volt battery is plenty . If you din't find trying different chainrings is good enough for you a couple of years ago I saw a thread and youtube videos from someone in Canada , one of the middle provences that overvolted a Befang mid-drive using a controller from Grin Technolgies , I looked into it more and found the price to be so much money that just buying a CYC Cyclone 3000 watt ( really 1500 watts continuous ) or the at the time CYC X1 pro , would be about the same price as putting a higher power controller on the BBSxx motor. And allot less work than over volting a Befang . At the present time I am quite happy with the BBSHD and stock controller , It powers up some very steep 5+mile long mountain roads .