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How do I maximize top speed

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    #31
    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....

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      #32
      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, 07:28 AM.

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        #33
        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.

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          #34
          Installed a wheel build with 13 gauge spokes and dual drive sram tandem rim. Getting full range from 36 sprocket to 13 to 34 cassette. Wants to spin rear 700c rear wheel to above 34 mph in high gear bbs02 motor only, flat no wind hot off charger etc.. Exceedingly quick from dead stop. 8 mph is fastest speed in low graanny gear Excellent quick shifting. Using the 48 sprocket still strong in low range, but higher speeds not possible without a good downhill. My speedo goes nuts above 34, can not count fast enough from 20 inch front wheel. Ready for aero tests. As a cargo bike, recumbent with cargo below the seats is superb in handling. Chain stretch so far has been no problem. Will cry when i need to replace it. Equivalent to three normal chains. No neck wrist back or arm pains. Super comfortable ride. Even worked well on trails. Spins out a way bit ez.
          better miles per kwh on street than mtb with faster speeds and more comfort. Faster in turns.
          Lazy boy.

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            #35
            Originally posted by Gr8fun View Post
            Installed a wheel build with 13 gauge spokes and dual drive sram tandem rim. Getting full range from 36 sprocket to 13 to 34 cassette. Wants to spin rear 700c rear wheel to above 34 mph in high gear bbs02 motor only, flat no wind hot off charger etc.. Exceedingly quick from dead stop. 8 mph is fastest speed in low graanny gear Excellent quick shifting. Using the 48 sprocket still strong in low range, but higher speeds not possible without a good downhill. My speedo goes nuts above 34, can not count fast enough from 20 inch front wheel. Ready for aero tests. As a cargo bike, recumbent with cargo below the seats is superb in handling. Chain stretch so far has been no problem. Will cry when i need to replace it. Equivalent to three normal chains. No neck wrist back or arm pains. Super comfortable ride. Even worked well on trails. Spins out a way bit ez.
            better miles per kwh on street than mtb with faster speeds and more comfort. Faster in turns.
            Lazy boy.
            I had the pleasure of Dan's company while he built this rear wheel. Dan is a class act all the way.

            Before he installed this IGH, him and I rode through a taqueria drive through on each other's bikes. Fun time!

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            • Gr8fun
              Gr8fun commented
              Editing a comment
              Actually commutor ebikes is my mentor on wheel building. And has the tools needed for a good build.

              It is a very exacting and tedious process, the results can be satisfying when you get what you want.
              Last edited by Gr8fun; 04-27-2018, 03:59 PM.

            #36
            Some thoughts on achieving top speed. Check all connections are good and corrosion free. No voltage robbing resistance. Good batteries fully charged. The type of batteries also may affect the top speed. I suspect that pf or q cells rather than ga cells in that having a higher amp rating will have lower voltage drop under high amperage. A larger battery will also have lower drop in voltage.
            using pas 9, shift up as you experience wattage drop , in each gear while pedaling will keep voltage drop down. This should keep voltage drop to a minimum, and allow a higher speed. Accelerate briskly but not excessively. Be in an appropriate gear that will give you a cadence that you can match. The faster the better. Bbs drives love rpm. You will be able to add some speed, by pedaling. Having a watt meter is good to watch in keeping it only slighly above watts neccesary to maintain current speed. Maybe 150. Take your time, develop speed over distance without depleting battery and increasing voltage drop. The battery also delivers more performance with warm temperature, not hot. 75 to 80 degrees may be ideal. Dont let your motor or battery get too hot. Damage will occur. Make sure air pressure is as high as possible.

            have the wind at your back and go downhill. Present smallest profile of yourself as posible to the wind obstruction coming at you..

            of course thinner tires, lighter weight, and fairings will also be helpful. What is the most you can get out of one horsepower?

            this is a bicycle and not designed to drive at these speeds. Unsafe and not advisable. Wear a helmet.
            Last edited by Gr8fun; 04-28-2018, 06:58 AM.

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              #37
              Following my own instructions i only gained maybe 1.5 mph between a full battery and 1/2.
              the incr re ased rpms with higher voltage did allow higher max speed in lower gears.

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                #38
                I've got a BBSHD on a heavy Ohm frame with Schwalbe Marathon+ tires (26" x 2"-ish). The bike with battery and accessories weighs just over 60 lbs. I usually carry about 15 lbs of cargo with me on my commute. I weigh 175 lbs (180 fully dressed). So that's a total weight of about 255 lbs. I currently use a 48V 16 ah battery (and often only have it charged to 85-90% when I start my ride).

                If I pedal hard at highest PAS level and engage the throttle on a long flat smooth stretch that is about 3 miles into my commute, I can generally hit 38-40 mph per the display. I haven't yet verified that against GPS, but based on other anecdotal observations, there's no reason to believe the display is inconsistent with actual speed.

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