Right before my Bafang BPM2 bite the dust, I ordered a MXUS 1307 direct drive hub motor from Austrian ebike shop elfKW for a change. The MXUS 1307 is a 9Continent 2807 clone, I think.
Since the MXUS came laced in a 20″ rim and I had no spokes ready at hand to relace it in a new nice and sturdy Bellacoola 559 x 35 mm downhill rim, it went straight into the Sprint for a test. It didn’t took long to realise, the Sprint 26 with all around 20″ wheels handles way better around corners than my former 24″ front/26″ rear wheel setup. Shure, the 24″ front wheels are more comfortable and roll noticeably better, but corner handling is still a bit compromised. (more on that later)
Back to the hub motor. It is rated at 330 rpm at 37 volt. Thats about 30km/h in a 20″ wheel. Slightly to slow for my needs.
Paired with a 74 volt battery and 30A controller on the other hand, this 5.5kg hub produces quite impressive acceleration and 56km/h top speed in my Sprint. Fun!
Even more fun on gravel or wet tarmac when drifting around corners. Unfortunately, with the current 55 tooth chain ring, I’m running out of gears above 40km/h. After consulting Mike Sherman’s Online Gear Calculator and Grin Tech’s Hub Motor Simulator I’ve ordered a 65 tooth chain ring.
Since my 20″ front wheel set with 70mm Sturmey Archer drum brakes is pretty much shot after serving for more than three years and running just shy of 20,000km in the Sprint, I have to get new 20″ front wheels. Remembering how much I liked the even more nimble handling of the Sprint with 24″ rear wheel I decided building a 20″ front/24″ rear wheel setup with extra wide rims.
I thought about disc brakes for a while but in the end choose nearly maintanance free 90mm Sturmey Archer drums again to be laced in shiny brushed 406 x 40 mm rims from Classic Cycle and a similar 507 x 40 mm rim for the MXUS. The brushed rims look impressive all by themself already and the drum brake hubs will fit very nicely to them, I think. The spokes should arrive in the next two days and on the weekend I’m wheelbuilding. (still haven’t finished the truing stand, though)