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Looking for Insight and Wisdom - Cannondale Tandem 29er

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    Looking for Insight and Wisdom - Cannondale Tandem 29er

    Greetings Experts! I'm a newbie here looking for advice on converting my Cannondale Tandem 29er:

    I've searched extensively and haven't been able to find anyone who has attempted an ebike conversion on this bike. Based upon what I have read, it seems a BBSHD would be the way to go, but I'm open to any and all suggestions. The bike has an eccentric front BB30, 68 mm width. I believe the rear BB is also BB30. My first inclination is to mount to the front BB, but I have seen them set up both ways. I've included views of both bottom brackets from the top down to capture the chainrings. FWIW, front dropout is 100 mm, rear is 145 mm. Frame is aluminum, bike weighs 39 pounds.
    Last edited by BigJim; 03-01-2018, 03:32 PM. Reason: Added Bottom Bracket Detail

    #2
    The cranksets use Shimano hollow tech which will be a problem if you are trying reuse your crank arms and sprockets.

    Comment


    • BigJim
      BigJim commented
      Editing a comment
      Thanks Calfee20! You are right. I never realized this bike had such unique crank parts. I realized the spindles were essentially hollow, but I never gave it a thought until now. That said, I agree this adds another element of complexity to going mid-drive. Thanks for the insight and wisdom, that's why I came here.

    #3
    We have seen only a few successful mid drive conversions of tandem bikes. I can't say it'll work especially with that shell, is that american-style eccentric? If so we have an adapter for it, if not then it may be more difficult to source.

    It would be a lot easier to pop a front hubmotor on there and call it a day. Not saying it's impossible but could be more difficult than a standard BBSHD build if you want to go that route. See below for a couple examples of mid drive tandem builds folks have submitted to Luna build gallery. Both of them used bbs02, one used front and the other used rear.


    BBS02 build. The HD won't fit in the tandem - too wide and interferes with stoker's timing chainring.
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    BBS02
    An easy & painless process of building an electric bike.

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    Comment


    • BigJim
      BigJim commented
      Editing a comment
      Will my 145 mm rear dropout spacing be an issue?

    • calfee20
      calfee20 commented
      Editing a comment
      No. Get a hub with 135mm spacing and add some washers. I moved an Edge 1500 up to 170mm with washers and torque arms.
      http://www.ebikes.ca/shop/electric-b...pacewash3.html

      The Edge would be a good motor for that. A cycle analyst would allow you to setup either PAS or torque sensing. https://www.electricbike.com/edge-1500w/

    • ianboag
      ianboag commented
      Editing a comment
      FWIW I just converted a Bike Friday to a front hubmotor - sort of because I am old and I could. For $250 I got a kit from China (aliexpress)that included everything (new whee with 250W motor and all thr controller stuff. No battery. Fitting was pretty simple as the wires/plugs were color coded.

    #4
    One word of warning, you will go through a lot of chains using a mid-drive setup. I set ours up on the captains BB and it worked okay. It makes shifting more finicky (for a tandem). I needed new chains at 1000 miles and iours is a recumbent that uses 5 regular chains! I ended up changing to a rear hub motor and I like it a lot better.

    Comment


    • calfee20
      calfee20 commented
      Editing a comment
      THAT is good information!!!

    • BigJim
      BigJim commented
      Editing a comment
      BK Xray, thanks for the insight. I am quickly learning that going the mid motor route for this particular bike might be much more complicated and expensive (as well as less efficient) than going the hub motor route.

    #5
    I'm having a hard time visualizing how I'd get my disc brake to align with the 135mm width hub through the use of spacers. I don't have a great deal of space available on the freewheel side, although I'm sure I could drop down to a 7 or 8 cog freewheel instead of the current 10 speed version. (Pic below)

    Calfee20 mentioned using an Edge motor, I'm having a hard time finding one right now (at least in the US). I did run across the Double Gear/Double Torque Motor which sports a 145 mm spacing. Any thoughts on this? Also, what about the famed MAC Motor/ASI High Performance Hub Kit? I would need a Rear 12T model, which I don't see listed.

    Also, do you think my rear triangle/dropouts are beefy enough to handle any of these without torque arms? They seem to be pretty substantial. (see pics)

    Thanks again for all the help!

    Comment


    • BK Xray
      BK Xray commented
      Editing a comment
      I am kind of looking into the Double Gear/Double Torque Motor as well. We also have 145mm spacing in the rear. I like the idea of being able to use a cassette instead of a freewheel because cassettes are cheaper and have more sizes available. I would still use at least one torque arm, just to be sure. I like the ones put out by Grin because they fit tight on the axle and are very strong.

    #6
    Originally posted by BigJim View Post
    I'm having a hard time visualizing how I'd get my disc brake to align with the 135mm width hub through the use of spacers. I don't have a great deal of space available on the freewheel side, although I'm sure I could drop down to a 7 or 8 cog freewheel instead of the current 10 speed version. (Pic below)

    Calfee20 mentioned using an Edge motor, I'm having a hard time finding one right now (at least in the US). I did run across the Double Gear/Double Torque Motor which sports a 145 mm spacing. Any thoughts on this? Also, what about the famed MAC Motor/ASI High Performance Hub Kit? I would need a Rear 12T model, which I don't see listed.

    Also, do you think my rear triangle/dropouts are beefy enough to handle any of these without torque arms? They seem to be pretty substantial. (see pics)

    Thanks again for all the help!
    I always match my motor dropouts to my frame dropouts. If the frame has 135mm dropouts, I would use a motor with 135mm dropouts. Some people say that it is okay to spread the dropouts on a steel frame, but this sure doesn't keep the dropouts on the frame parallel to each other. Frame builders take a lot of care to get these parallel; I would keep them where they are. You can always get a hold of a different frame with wider dropouts if you need more room for a wider motor (to minimize heat) and/or wider cassette.

    I would also always use torque arms for anything above 750W for a steel frame. What material is your frame? I have cracked open the dropouts on a 4130 chromoly steel frame by not using torque arms; that was an expensive mistake.

    If you want to put a hub motor in the 135mm dropout frame, I would recommend the most narrow motor that will give you the power you need. The problem with a narrow motor is that the hub motor will be more susceptible to overheating than a wider motor.

    If you put a hub motor in a frame with 135mm dropouts, you won't have very much room for a wide cassette, depending on how narrow or wide of a motor you choose.

    For reference, I use a 50mm wide hub motor in 170mm dropouts with a single speed freewheel (only 2mm to spare) and a 50mm wide hub motor in 190mm drpouts with a 5-speed cassette (1mm to spare).

    I have also used a 40mm wide hub motor in 170mm dropouts and a 7-speed cassette with over 1/2" to spare, but the 40mm motor would overheat on almost every ride.
    Last edited by commuter ebikes; 03-08-2018, 09:13 PM.

    Comment


      #7
      Originally posted by BigJim View Post
      I'm having a hard time visualizing how I'd get my disc brake to align with the 135mm width hub through the use of spacers. I don't have a great deal of space available on the freewheel side, although I'm sure I could drop down to a 7 or 8 cog freewheel instead of the current 10 speed version. (Pic below)

      Calfee20 mentioned using an Edge motor, I'm having a hard time finding one right now (at least in the US). I did run across the Double Gear/Double Torque Motor which sports a 145 mm spacing. Any thoughts on this? Also, what about the famed MAC Motor/ASI High Performance Hub Kit? I would need a Rear 12T model, which I don't see listed.

      Also, do you think my rear triangle/dropouts are beefy enough to handle any of these without torque arms? They seem to be pretty substantial. (see pics)

      Thanks again for all the help!
      The "Edge" motor was a name given to a motor that only a couple of people were carrying. The important specs are it is a 205 motor with a 35mm wide stator that was made from Aluminum. The laminations are also constructed from .35mm steel. If you want to read about them spinningmagnets did an article on them. http://www.electricbike.com/edge-1500w/

      I have one and I am very pleased with it. When they first came out everyone was trying to figure out who was making them. Greenwerks and I are 99% sure that they are made by Mxus and you can get them with the same specs as the one in article from West Coast Electric Cycles. http://westcoastelectrics.com/product/35mm-ddhub/ He has two different windings and I would suggest talking to them about which would be the best for your application.

      Since your dropouts are 10mm wider than the hub you can slide the hub back and forth to get the clearance you will need for your brakes and gears "freewheel". Then the rim will have to be spoked with the proper dish to center it.

      There are a lot of PAS and torque sensors that will fit your rear BB. Grin Ebike has a huge selection of them now. http://www.ebikes.ca/shop/electric-b...e-sensors.html They also have a new motor made by Mxus that they just announced about a week ago. It has all of the same specs except it takes cassettes instead of freewheels and is 5mm narrower at the stator. So slightly less power and a little lighter. http://www.ebikes.ca/shop/electric-b...mx3005rc.html#




      They are also available in two different windings. My personal experience has been very good with both stores.

      Comment


      #8
      There is another new motor. I have no experience with it but it looks interesting. It is small and light weight and you could make a very stealthy system with it. http://www.ebikes.ca/shop/electric-b...mg310-fst.html It is supposed to be silent unlike most geared hub motors.

      Comment


        #9
        I installed a BBSHD on our Calfee Carbon Fiber tandem. The tech from Calfee walked me through the process. I installed the motor in the stoker position and went with RH drive for the front to rear chain. A pair of fixie cranks from eBay solved the drive crank issue.

        You may have to get a new front eccentric so that you can use conventional cranks.

        Pictures and details upon request.

        Wayne
        wthais@mchsi.com

        Comment


        • paxtana
          paxtana commented
          Editing a comment
          I for one would love some pics / details.

        • calfee20
          calfee20 commented
          Editing a comment
          I second that. The forum needs more tandem and cargo bike builds.

        • BigJim
          BigJim commented
          Editing a comment
          DubT
          That is a truly beautiful bike! I'd love to see more pictures and details. Do you miss the front derailleur? Yours is certainly one of the most elegant conversions I have seen.

        #10
        How is the best way to post pictures?

        Comment


        • paxtana
          paxtana commented
          Editing a comment
          Personally my favorite is to drag and drop them. This inserts them full-size wherever you dragged it but you can resize by double-clicking and selecting the size you want.

          Alternately you can use the upload attachments icon.

          Only catch with the icon is that a lot of folks do not realize just because the images are attached, that does not mean they are inserted. The attachments will be shown below the text editor with sizes you can insert. If none of this is selected it just add thumbnails and puts the actual images into a little photo slideshow thing at the bottom of the post that you have to click to see the pics. (for example see the first post on this thread)

          It can take a little getting used to. There's actually a few other ways to upload pics as well just in case that was not complicated enough.

        #11
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          #12
          I initially built the bike using a chain for the tandem drive, I have since installed a Gates belt.

          I built in July of 2017 and we have ridden it 3247 trouble free fun miles. We normally only ride in level 1 of the 9 available.
          Attached Files

          Comment


            #13
            DubT Really nice looking bike..got a few questions.

            How exactly are you connecting second chain ring to the spare axle?

            How are the arms and external ring moving independently from the Eclipse?

            Did you encounter any difficulties in alignment when swapping this over to belt drive?

            Comment


              #14
              The second chain ring is attached to the square drive fixie crankset and attaches directly to the Bafang spindle.

              The eclipse is bolted to the Bafang motor and the fixie crank attaches to the Bafang shaft. It replaces a single crankarm.

              I had to get a special long square drive front spindle from Phil Wood. A LBS ordered it for me. The Q factor is wide but it is not an issue.
              Last edited by DubT; 03-13-2018, 10:44 AM.

              Comment


                #15
                Well, I'm just about to pull the trigger. I'm looking very seriously at the Double Torque/Double Gear hub at Luna. Saw a pretty comprehensive discussion at https://electricbike.com/forum/forum/kits/direct-drive-hubs/28482-double-gear-double-torque-motor . I'm also considering the giant Panasonic "Flat Fish" 52v 20ah 1100 watt hour battery pack. This seems to offer a lot of power at a relatively low cost per ah. Does anyone have experience with these?

                Thanks in advance!

                Comment

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