planning a mid-drive Rockhopper ebike conversion, advice?


New Member
Hi folks, weathers pretty sucky outside (snowing like crazy), so good time to get serious about my winter bike project. Here's the skinny -

Specialized Rockhopper 29'er
want middrive
will use primarily for commuting to work 12 mi each way and just want to supplement my pedaling effort to maintain a good speed (15-20 mph), and some help on the hills.

seems the Bafang BBS kits are pretty popular, and the 350-750w sizes are pretty reasonably priced. any reason NOT to pursue that approach?

also, any recommendations for battery? would be nice if it had a simple design that makes it look the bike was originally designed with it to begin with.


New Member
I am interested in following along! I am planning a DIY myself for commuting around campus and the many hills it has so I do not have much advice. Best of luck, I'd love to hear some updates


Well-Known Member
Unless you are going out and single tracking I'd go for a much simpler hub drive. I have every BBS model made. I like them, but they are more maintenance. I'd suggest that for a great campus bike and simplicity go for a hub drive. MAC, GeorgeS runs them, and Magic Pie. The pie has an internal controller making one less item to hang on the bike. BOTH are very stable platforms and reliable. The BBS series, especially the lower wattage require using your gearing to keep them running at highest revolution to avoid lugging the motor. Many a BBS has been murdered by poor shifting management.
You don't mention what the hills are like, but my friend in SF runs a MAC 10T there. A complete MAC kit with a HIGH quality battery from EM3ev would run $1,059.50 Delivered. Thee is no comparison when it comes to battery build quality.
I have EM3ev, Lectric, Luna, Unit Pack Power, and AllCell batteries.

THE ONLY HITCH IS HOW HILLY IS THE RIDE? Hemdan on ES Facebook can attest to the abilities of the geared hub.