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BBSHD in modified frame

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    BBSHD in modified frame

    Has anyone modified their aluminum frame on bikes where the BBSHD motor hangs down in order to rotate the power unit up higher for more ground clearance?

    #2
    No, not with aluminium. I've just started chopping up an old street frame to accept the BBSHD and route all the wiring thru the frame for a clean install.
    Aluminium would be harder to do yourself if you don't have the experience and proper tools. After welding and bracketing, I'll repaint the entire bike and throw on some new decals for the final touch.

    Cheers, Kris
    Last edited by .Eek; 02-21-2021, 05:48 AM.

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    • merlin4194
      merlin4194 commented
      Editing a comment
      Ya, that's what I was thinking, as far as the motor clearance anyway. I'm not set up for welding aluminum anymore but I could do the fabricating then take it to a welding shop. Could you get a close up of the motor clearance area? Maybe from the left side? Did you measure how much you were able to move the motor up afterwards?

    #3
    The 3rd photo looks to me like that frame is already history as far as any application where ground clearance is an issue. From the horizontal dropouts and headbanger components I would have gone with a hub motor for that one.

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      #4
      As the frame is cut up like this - and I do not recommend this to anyone - I share your concerns regarding the structural integrity Retrorockit ;-) As soon as I receive the Phaserunner and 30T sprocket, I'll continue to build it back up, and hopefully stronger than it was.

      I really like the bike how it handles without the motor, and the wheel set is virtually bombproof. It would be a shame to throw in a hub motor in my opinion, and I really don't want to add any rotating mass. In the back that would effect the handling a little bit less than up front, but a hub motor would be an eye sore as well. That is important for me with this build, hence I've moved the motor up a bit, so it's inline with the bottom bracket. Ground clearance is not really a reason for me to get it up higher, it's more the esthetics. Thats why all the cables will also be tucked into the frame, and I'll run it without any extra sensors or display. Just a thumb throttle.

      At the chain stays I have enough room to weld in a nice beefy U, that clears the 24/2.5 rear tire. The same goes for the underside of the downtube, but that will be a bit more rounded.
      The top of the downtube will be fitted with a plate, thick enough to tap in some threads, that accepts the battery nicely on a flat surface. One of the last steps will be to connect the top front of the motor to the downtube, so it will become a structural part of the frame. The questionable bracket that clamps (!?!) the motor to the frame, will be welded as well.

      In theory I think I can get a satisfying result, but we all know how project can turn out ;-)

      Cheers, Kris
      Last edited by .Eek; 02-21-2021, 02:21 PM.

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        #5
        If you have the tools and skill to put back the metal you've removed then go for it! But when someone has to ask how to do something like that, I kind of assume they're asking because they don't know.
        I can tell you that adding a BBSHD and battery will shift the weight balance well forward. Most of a riders weight is carried behind the cranks. Some of the geared hub motors can hide behind a decent sized brake rotor. Rotating mass is a real consideration, but when it's near the axle, and producing power it's not the same sort of loss as heavy rims and huge tires. Do you plan on adding any gears to it? A BBSHD can move a bike like that up to 35mph. Are you planning on doing any pedalling, or just use it as a scooter?
        .

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          #6
          Hi Retrorockit! More building it as a scooter, with a single speed setup. As nimble as possible, hence not going for a hub motor. I agree in the rear the rotary mass will have less effect, especially when it's in the center of the wheel, and a hub motor would definitialy would improve the wheeling capabilities ;-) It will all have it's pro's and cons, and we'll find out how it handles soon enough I hope.

          I've stared a new thread, so not highjacking Merlin's thread anymore ;-)

          Cheers, Kris

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            #7
            Originally posted by .Eek View Post
            No, not with aluminium. I've just started chopping up an old street frame to accept the BBSHD and route all the wiring thru the frame for a clean install.
            Aluminium would be harder to do yourself if you don't have the experience and proper tools. After welding and bracketing, I'll repaint the entire bike and throw on some new decals for the final touch.

            Cheers, Kris
            Aluminium is not that hard to work with. Welding is kind of like my hobby, but as from my experience it`s pretty easy, if you have a tig like Hobart or AHP like this one, for example.
            I used them when I was repairing a frame on my bike
            Last edited by RobRi; 11-16-2021, 01:35 AM.

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              #8
              With a single speed I would go hub motor. No extra driveline loads to contend with. Solid motors are silent, Geared motors lighter. Regeneration is an option. Torque sensing also.
              Grin Products in Canada is a good resource for those. Their E bike simulator models hub motors, and mid drives with all relevant variables included. That includes ferro fluid filled motors.
              https://ebikes.ca/product-info/grin-products.html
              Simulator.
              https://ebikes.ca/tools/simulator.html
              For multispeed I'm BBSHD all the way. But singlespeed favors hub motors. The derailer on hubmotors is just to match the riders cadence to bike speed.

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                #9
                I've seen a couple of conversions where the owner/rider literally hammered in the front of the downtube to get more clearance for the BBSHD...insane. One of them was on a very nice older Santa Cruz VP Free or V10...can't remember which one now. That will not work for long. As to rewelding a lot of the higher end aluminum frames that are damaged, this "can" screw up the heat treating on many of them. That may not sound like a big deal, but most of the better frames out there have been designed to drop as much weight as possible and then engineered by design and heat treating to maintain strength. It won't always be a problem, but it can be. Now when you go highly modifying the original frame design to accommodate a motor, it probably becomes more of an issue. And add to that the fact that a BBSHD puts more stress on the frame and components...at least if used aggressively...your welding skills and even some engineering and design experience had probably better be at a decent level. Still, not a lot of things are totally impossible when enough knowledge and skill are involved.

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