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How do I maximize top speed

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    I run a terribly inefficient big fat-bike with BBSHD. With a 39t front 11t back I've exceeded 35mph (per GPS) on flat hard smooth ground and I've never maxed it out - 30+ is frightful....


      I just had my first powered flight of what I think I will call 2Fat... my 2nd gen AWD bike. BBSHD on the back and fat Bafang geared hub motor on the front.

      Shutting off the front motor, flat ground no wind all throttle and me @ 240 lbs I got 28 mph on a 42x12 gear... which is just over 111 inches on 26x4.9 Big Fatty tires.

      Bike is really smooth and light for what it is. Titanium frame and only one hi output 25R battery. No panniers or load of garbahge in them in that test ride like it will have normally. Rear cluster is a 9-speed 12-34. I am going to swap in an 11-32 and see what that tooth gives me. Its a Shimano HG-400 cluster so steel and welded together, but the 11-tooth has to have the last two cogs loose. Long term may be better to run the 12-34 where the 14T is smallest of the solid welded block, or if lucky keep the 11 and run higher rpms on the middler cogs to keep the motor happier. Will do a writeup here when I get it nailed down better.

      With the front motor engaged on full throttle, hit 32, which matches my AWD 2x750 Bafang fat hub motor bike when fully loaded. However those Bafang fat motors use a lot less power. 35a peak but onlyh 17a is continuous at cruise. I saw the BBSHD nail the watts to a constant 1500 and stay there. Surprised as I thought a mid was supposed to be more efficient than a geared hub.

      edit: I am still using 5-level PAS and Luna stock hot rod programming. I am sure there's some optimization to be had in BBSHD programming.
      Last edited by MoneyPit; 01-26-2018, 08:28 AM.


        My unlocked bbs02 fat bike maxed out at about 38 mph stock programming (from biktrix) with the original 46 or 48 tooth saw blade up front, and an 11-28 7 speed cassette in back, battery 11.6 AH 48v. When i upgraded to a 10 speed 11-36t, with a 36t bling ring up front i now only get ~32mph. All speeds are on the flats. Im also 6'2" and about 145 lbs, so i am a little easier for the bike, but both of those speeds were verified by the helpful little police radars on the road (felt so happy to be "speeding" on an ebike in a 30 MPH school zone!) and i was holding down the throttle as well as pedaling so fast that the bike felt too wobbly to be safe. From what i hear the bbshd is much more powerful than the bbs02 so I would certainly imagine it being able to do well over 30. Perhaps you should get a programming cable and see if it actually took the hot rod programming. Ive forgotten to click "write" before switching menus and then lost the settings i modified. At stock level of 1000 watts i would imagine to get just about 25 mph if i was throttle only. At 1200w my unlocked bbs02 will sit just about 28mph full throttle with NO pedaling.