No announcement yet.

Comparability with belt drives?

  • Filter
  • Time
  • Show
Clear All
new posts

    Comparability with belt drives?

    I've been thinking about buying a Montague folder, then adding a Bafang motor. Probably the BB02, because going over 750W has legal consequences in my state.

    The Montague Allston looks intriguing. It uses a Gates carbon belt drive and Shimano Alfine 11 internal gear hub.

    Will the Bafang work with a carbon belt drive?

    It possible but you don't have the same selection of offsets for chain ring so you may have more issues than usual trying to get a good chain line or belt in this case.

    What have you run into that makes you think anyone knows or cares about E bike power ratings in this state?


      Originally posted by 73Eldo View Post
      What have you run into that makes you think anyone knows or cares about E bike power ratings in this state?
      MN Stat 169.011 Subdv 27

      Electric-assisted bicycle" means a bicycle with two or three wheels that: (1) has a saddle and fully operable pedals for human propulsion;

      (2) meets the requirements for bicycles under Code of Federal Regulations, title 16, part 1512, or successor requirements;

      (3) is equipped with an electric motor that has a power output of not more than 750 watts; and

      (4) meets the requirements of a class 1, class 2, or class 3 electric-assisted bicycle.
      Whether anyone cares or not, or anyone will ever look at it closely enough to notice that I have a 1000W motor, I can't tell. But current law is specific.


        The Montague Allston (and Montagues in general) look like one of the best and well executed production full size folders.

        Talking specifically to the idea of installing a BBS series motor onto the belt drive Montague Allston, there are some issues. First off, the BBSHD cannot be made to align with the very tight Alfine beltline, without resorting to chopping back the right side of the BB (which is not possible on this bike - more on this later). The BBSHD front to Alfine back belt line numbers just don't work. Keep in mind, the belt front to back alignment must be spot on - a chain on the other hand, especially the 3/32 derailleur variety will tolerate misalignment.

        So, what about the plenty powerful BBS02 motor and the belt? Side track - the BBS02 motor can punch hard, just not for very long compared to the BBSHD. Back to the belt - the only belt drive Alfine BBS02 build I can recall was this Spot Brand Acme, done over 6 years ago, but little detail on the "how" was provided. The only clue given was, "the new CDX drive makes this possible":
        Click image for larger version  Name:	spot re touch smaller.jpg Views:	0 Size:	158.4 KB ID:	150370

        The front belt pulley looks to be stock Gates part, mounted on a 130BCD to BBS02 spider. Hard to tell what else if anything was done. Note that the belt tensioning is accomplished by the sliding dropouts. Also note - if Gates CDX (versus the less expensive CDN) components were used, you're looking at approx. $300 for the two pulleys and the belt, meaning you'd better get the ratio right the first time. Gates holds the design patent and there are no other Gates compatible part sources.

        So, back to the Montague Allston - it's frame uses an eccentric bottom bracket, which would not normally be an issue except when you try to install a BBS motor into it:

        Click image for larger version  Name:	16501132645044094450014715701232.jpg Views:	0 Size:	181.4 KB ID:	150371

        See those holes? They're the belt tensioning eccentric rotation adjustment / locking access points, which would potentially be blocked off by the stock BBS-style anchor plate:

        Click image for larger version  Name:	51+PfOTSZNL._AC_SL1000_.jpg Views:	0 Size:	39.9 KB ID:	150372

        I'm thinking the anchor plate could be notched as needed, but the related fasteners would still cause some blockage. The bigger concern I would have is that the BBS motor anchor plate locks the motor to the rotating eccentric, and the motor applies quite a bit of twisting force. Would the eccentric's lock be strong enough to withstand it?

        Finally, the other nuisance with the Montague frames in general is mounting the battery - underslung seems the most common way, and there have been some tube clamp improvements and availability making this issue somewhat easier to work out.

        I looked at this bike years ago, with the BBS02, and nixed the thought. Mostly, oddly enough because I don't like the belt drive negatives of 1.) perfect alignment required and 2.) the cost. I fool with my bike's overall ratios quite a bit. If my bikes were belt drive, such fiddling would cost a fortune. I also don't care for the battery mounting situation.

        The above related to belt drive BBS motor to Alfine hub setups. With the Rohloff's 55mm belt line life is much easier and the are many such belt drive BBSHD to Rohloff builds.
        Last edited by ncmired; 04-16-2022, 09:39 AM.
        BBSHD / BBS02 IGH Builds: Nexus / Alfine 8: 1 2 3 4 5 6, Rohloff: 1


          This might be useful.


            Thanks for that.

            I'm looking for something to carry on a boat for transportation wherever I stop, and I was thinking the Allston might be less vulnerable to salt air.

            The more traditional drive trains on the other Montagues might need more PMCS, but parts availability would be better. And quite a few people have fit BBSHD and BBS02 to them.


              Originally posted by Jdege View Post
              I'm looking for something to carry on a boat for transportation wherever I stop, and I was thinking the Allston might be less vulnerable to salt air.
              I've been following your snippets on future cruising life, and wondered if you'd care to disclose your boat type - keel sail, trimaran, motorsailer, a Ranger-like tug, something else? If that, maybe roughly where (east coast ICW, great lakes circle, Caribbean, Northwest passages, etc.)

              I've got an uncle who's completed a world circumnavigation (sail), and a cousin who's completed most of the North America loops (via Ranger Tug).

              Will understand if you'd rather not disclose any details. As a former inland / ICW / near shore boater, I'm just envious!
              Last edited by ncmired; 04-16-2022, 11:19 AM.
              BBSHD / BBS02 IGH Builds: Nexus / Alfine 8: 1 2 3 4 5 6, Rohloff: 1


                What I have is a Vaitses/Herreshoff Meadowlark.

                It's a 37 foot ketch, with an eight-foot beam, 20-inch draft, masts on tabernacles, and leeboards.

                She should be a great boat for the Bahamas or the Florida Keys.

                She needs a lot of work to get ready, but Minnesota isn't cooperating. I need to do a bit of fiberglass work, before I do bottom paint, and for that I need low temps above 45F.

                High and low for today are 39F/25F. Maybe I'll be able to start work on Friday - unless the forecast changes.


                  Wow - 20 inch draft, and I'd guess the prop is protected by a bit of keel - maybe beach it wherever to clean the bottom up? And it's mostly fiberglass and maybe towable too - what does it weigh?

                  I don't see any side lifelines, and are you thinking of a Bimini / solar panels and the like? Thinking about a bicycle battery, I'd consider buying a (yes) LIPO battery, and storing it in a white box on that taffrail (and run the charger power up to it). You'll probably have other LIPO batteries on board as well for hand tools, radio power backup - just guessing.

                  Oh, and do you have any idea how long it'll take to drop the masts to get under a stationary bridge (or whatever)?

                  That's a really nice, adventurous boat - congrats!
                  Last edited by ncmired; 04-26-2022, 10:00 AM.
                  BBSHD / BBS02 IGH Builds: Nexus / Alfine 8: 1 2 3 4 5 6, Rohloff: 1


                    She's 12,000 pounds, with 4,000 pounds of lead in her keel.

                    As originally designed she had two props, each driven by a 5hp gas engine. What she has now is a single prop driven by a 27hp diesel.

                    With just one prop tucked up alongside her keel the way it is, at slow speeds or in reverse she steers like a pig.

                    I'm seriously considering pulling the diesel and putting in a pair of electric pod drives. But there's plenty on the list before I get to that (including stanchions and lifelines).
                    Attached Files


                      That drive ... oh boy ... Is Torqeedo in the pod business? Looks like nice equipment, till you get to the price list.

                      Oh wait, this is marine - what am I thinking.
                      BBSHD / BBS02 IGH Builds: Nexus / Alfine 8: 1 2 3 4 5 6, Rohloff: 1


                        Torqueedo makes pods. I've been looking at ePropulsion.
                        The biggest part of the cost is the batteries.


                          Grin Technology is doing a marine motor with their big hub motor to replace diesels on sail boats. May be not big enough even with 2 of them,but a tie in between E bikes and sailboats.



                            It's a sailboat. It didn't take much to push it slowly, and no matter how hard you push you'll not go fast.

                            I'm looking at pod drives to free up space inside the hull. There are three ePropulsion pod models - 1kW, 3kW, and 6kW.

                            A pair of 1kW should drive my boat to 4.5 knots, 3kW to 6 knots, 6kW to 7 knots.


                              I know almost nothing about boats. Just an interesting use of a hubmotor. But 2 pods should solve your control problem.


                              • Retrorockit
                                Retrorockit commented
                                Editing a comment
                                I spoke to a 74 year old sailboat rigger yesterday (he's still doing it). He figures 6 Knots is about right to make headway against a tide running 4Kt in a channel.He also mentioned that some of the electric/sail boats can recharge when under sail.He's old school, but he's been in,on, and around the new stuff.