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Grandmother’s Tadpole Trike Gets a BBSHD Motor. Scarab 320 / Greenspeed GT1

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    Grandmother’s Tadpole Trike Gets a BBSHD Motor. Scarab 320 / Greenspeed GT1

    Grandmother’s Tadpole Trike Gets a BBSHD Motor. Note that Grandma, is a retired automotive research engineer in her 70s. She is not most grandmothers.

    My trike is a Scarab model 320 that I bought about 12 years ago. It was made in Refugio Texas, and is a cromoly steel, licensed copy of the Australian Greenspeed GT1. The Scarab is no longer in production. Mine is equipped with a 52/42 crankset that will be removed, an 11/32 8-speed Sram cassette, and a .67 / 1:1 / 1.33 Sram internal geared rear hub. At my age, I’m finding it harder and harder to keep up with young bicyclists on social group rides. My goal with this project was to create a pedal assist motorized trike that would help me keep up with the stronger riders. Click image for larger version

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    I received my BBSHD kit late Monday afternoon. It took about 4 hours to unpack and figure it all out, and get all the parts mounted on my trike. There was not one word of instruction supplied with the kit; is that a guy thing?? It’s a good idea to watch several build videos before you start your work.

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    Before starting work, I put all the parts that would be going onto the trike, including the battery, into a canvas bag and weighed them. Later, I weighed all the parts I took off. 16.7 pounds went on, minus 4.0 pounds taken off, equals a net increase of 12.7 pounds to the weight of my trike. All the parts mounted just like they would on a bicycle. There are plenty of YouTube videos to help you there. The only trouble I had with the materials was that I had to chase the threads for the two 6 x 1.00 mm bolt holes for the motor bracket before the bolts would screw into the motor. Overall, I am very pleased with the quality of the kit’s parts and the inclusion of all the little shims, bolts, connectors and other little parts that could be needed for an installation and for charging the battery. Luna and Bafang did a great job.

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    I have a 68 mm bottom bracket. When I first mounted the motor I used some of the provided spacers on the right side and then found the crank arms were not evenly spaced. Mounting the motor the second time without any spacers resulted in the cranks being evenly spaced from the boom. The cranks are a bit further apart from each other than the original crankset, but that’s not a problem. I bought the Luna Eclipse 42 tooth chainring. It is a nice piece of machining, MUCH nicer than the steel chainring that Bafang supplies. (The Luna crank wrench tool was helpful installing the motor. I suggest that you purchase it!) All wires were run and tie wrapped as far as they would go along the frame. I temporarily connected the battery to test the color display and saw that the motor runs when turning the cranks. That’s as far as I could go the first evening. And yes, I did do the work on my living room floor. Age has its privileges.

    AS EXPECTED for any trike installation, 6 of the supplied cables are too short.
    I needed extensions for the following:
    Red & black 10 gauge extension for the battery pack, at least 55”
    Yellow plug extension for the left brake sensor, at least 13”
    Yellow plugextension for the right brake sensor, at least 15”
    Yellow plug extension for the thumb throttle, at least 26”
    Yellow plug extension for the derailleur shift sensor, at least 33”
    Threaded connector extension for the speed sensor, at least 48”

    Tuesday morning I went to the nearby big electronics supply store to buy 10 gauge wire for my battery cable extension (the battery will be carried in the rear panniers). I also bought four size 10/12 crimp connectors, 14 feet of 4-conductor wire (they did not have 3-conductor), some shrink tubing, and a new wire stripping tool.

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    (TIPS) 10 gauge wire and crimp connectors for the battery cable can be found at most automotive stores. Spend the money for BOTH red and black 10 gauge wire. You’ll be connecting 48 or 52 volts and you DO NOT want to reverse polarity by mistake. If you are going to splice and solder to extend the smaller cables you will need a wire stripper for really small 24 gauge and 26 gauge wire. Luna has extension cables for the yellow-plug cables. They are only available in 40” length at $19.95 each. Luna also has extensions for the threaded-nut speed sensor cable. They are available only in 12” lengths at $19.95 each.

    I decided to make my own extensions for the battery cable, speed sensor, and the two brake sensors. I ordered two of the 40” yellow-plug extensions; one for the 33” derailleur shifting sensor extension I needed, and another for the thumb throttle that I will shorten from 40” to the 26” I need. The chocolate bars help calm me when I’m chopping up nice new cables.

    When I connected the battery to the extended battery cable and turned on the display to test my work, the display came on, but the motor didn’t run any more.

    (TIP) If using your own brake levers, as I am because I want to retain the parking brake feature in my existing levers, the little disc-shaped magnets have to be epoxied in place for the motor to run. I had only attached one of the magnets. As soon as I figured this out, and epoxied the second magnet in place, the motor ran again and rear wheel speed was indicated on the color display.

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    About the new color display, the Luna YouTube video about it is all you’ll need to understand most of the functions. It really is intuitive. I’m glad I ordered it. Also, it came with the 3 button control pad which is also intuitive compared to the 5 button control pad that might come with the black & white displays. The display came set for 5 levels of pedal assist. I reset it to 9 levels, so I might get smaller steps of assist. I also found that I needed a T-shaped handlebar extension bar for mounting the display.
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    My battery, the 52 volt Mighty Mini 6ah 30Q, arrived with a 54 volt charge. I decided on this 6”x3.25”x2.75” battery after Seb at Luna Customer Support suggested it because of its miniscule size and my intention to use my trike mainly as a pedal assist vehicle. If it doesn’t deliver enough range, I can always carry a second battery; and two batteries will still weigh less than 7 pounds. I made the battery cable long enough to allow a couple of battery mounting positions, depending on whether I want to use the big touring panniers or a small rack-mounted bag.

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    On Wednesday I finally got the trike outside to test it. I knew I’d have to be careful about shifting without a shift sensor connected, and I would not have a thumb throttle, but I would have pedal assist. While pedaling around in my neighborhood with the assist set at level 1, I was AMAZED!!! This motor has much more power than I expected. Pedaling on flat streets with the derailleur on the 11 tooth high gear and the Sram internal hub on 1:1, I could cruise at 12 – 14 miles per hour while just slowly spinning the pedals to keep the motor running. Going up a small hill I needed to apply some pressure pedaling and went up at 12 miles per hour while still in assist level 1. That’s compared to my usual 6 mph up that hill. I rode 7 miles around the neighborhood getting used to the motor. Max speed this outing was about 15 mph. Steering and handling were not changed from the added weight of the 9 1/2 pound motor on the boom.

    Now I found another problem to overcome. I used to lift my trike into the back of my little Volvo station wagon. With 9.5 pounds of motor hanging on the front of the boom and 3.3 pounds of battery in the panniers, I can’t easily lift it anymore. A trip to Home Depot, 3 pine boards, some cutting, screws, glue, and Velcro produced a loading ramp that can travel on the roof rack with the trike inside, and can slip inside the car while I’m out on a ride. Problem solved.

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    Wednesday evening I connected the Advanced 300 Watt Luna Charger to the battery. I set the battery and charger in the middle of the garage floor as a safety precaution (always a good practice). I chose the 1 amp slow charge and the 90% charge limit for my first try. The little battery voltage meter that came free with my battery is a nice product. I taped it to the side of the battery pack. When the charger’s green light came on to indicate the battery was charged the meter read 58 volts. After disconnecting the charger it settled to 57.4 volts.

    Thursday evening was my first real outing with the motor. I ride with a small group that leaves at 8:15 for an 8 – 10 mile ride through the city of San Antonio, with a stop at one of the several outdoor bars for sandwiches and drinks and socializing at our half way point. I usually start out with the front of the group and finish all by myself at the end of the ride, not able to keep up with the much younger bicyclists. Tonight was VERY different!!! I started out with the assist level at ZERO. After a few miles I switched to assist level 1, and found it easy to keep up with the leaders all evening. I shifted only with the 3-speed hub gear and left the cassette on the 11 tooth gear. The power (current) meter indicated anywhere from 3 to 6 amps when the motor was assisting and zero lots of the time I didn’t need assist. After passing through the courtyard in front of the Alamo near the end of our ride, there is a sprint on a deserted street that would normally leave me riding all by myself as the group vanishes in the distance. I pushed the assist level to 7 and the hub gear to the 1.33 overdrive; I blew past most of the group at what the Bafang display later said was a top speed of 31.3 mph. I finished with the leader, a 20 year old athletic young woman who races. WOW!!!! At the end of this 8 ½ mile ride, the battery level meter at the top of the display was still reading 100%. That must be because the display is programmed for a 48 volt battery and I’m using a 52 volt battery. I need to learn if the display can be reprogrammed. After resting for a couple of hours, the voltmeter attached to the battery shows 54.4 volts. 57.4 volts at the start, 54.4 volts after 8 ½ miles of mostly flat riding from a 3.3 pound battery pack is A LOT more than I ever expected.

    (TIP) the 52 volt battery is considered fully discharged when it reaches 41 volts. Setting the display to digitally show battery voltage instead of % is a better way for me to keep track of power consumption.

    Friday, I took my trike to the hills just north of San Antonio to test the climbing performance. I chose an area that used to be quite difficult for me on my road bike when I rode with a fast-paced club about ten years ago. My measurement of the grade on my test hill showed a 2” rise over a 24” run. That’s an 8% to 9% grade.

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    To start, I put the chain on the big 32 tooth 1st gear and the internal hub on the .67 underdrive. This is the lowest my trike will gear down. I put the pedal assist on level 7 like I had used the night before and found that there was no way I could keep up with the required pedal cadence going up the hill. I moved the derailleur up to 3rd gear and tried the hill again. To my surprise and delight, I powered up that hill at 14 – 15 mph using 20 – 22 amps off the battery. I went back down the hill, and back up, and back down, and back up, and back down, and back up, having the time of my life!! WOW!!! My playing on the hill drew the battery down from 54.4 to 53.3 volts. I had put another mile on the odometer.

    Saturday, I decided to see how much more range I could get from the little battery. There is a great greenway trail that runs along the Salado Creek near my home. I started my ride at McAllister Park with my battery reading 53.3 volts and headed south for 7 miles before turning back. As on my night ride, I rode with my gear cluster on the 11 tooth (high) gear and used only the 3 position hub gear for my shifting. Pedal assist was kept at level 1. This allowed me to get some mild exercise pedaling all the way, but pedaling was never difficult. On the way back, I stopped at a restaurant adjacent to the greenway to treat myself to quiche, salad, and mimosa. Back at the park, I had ridden 14.4 miles today. My battery now read 45.3 volts. Since charging the battery to 90%, I’d gone almost 24 miles on pedal assist level 1 with the Mighty Mini Cube 30Q, and still had some power left.

    The two yellow-plug 40” cable extensions I had ordered arrived just a few days aft er ordering them, and were easily installed.

    (TIPS) I saw one dealer’s video showing the electrical cable coming out of the gear sensor needs to face rear toward the cassette or freewheel. I found that is wrong. You can see that in my installation, the electric cable points toward the shifter. I got the proper instructions from the Gearsensor official website. If you feel lots of resistance when feeding the derailleur cable through the housing, you are going the wrong way. The cable needs to have a good clean cut when you install it into the housing. If you do not have a professional cable cutter to prepare your old cable, it would be wise to use a new derailleur cable.

    When testing the gear sensor, I found that it worked exactly as expected. It momentarily cuts motor power during the shift so I can make my shifts without stressing the derailleur or cassette gears. On my 4th ride with my new motor I found myself occasionally stressing the internal hub gears while shifting under power. I’m going to order a hub gear sensor and a y-connector which I hope will be cheap insurance against expensive breakage.

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    Here is what I bought to motorize my tadpole trike:
    Item Price
    Base BBSHD Kit 750 watt 669.00
    Bafang Full Color Display 45.00
    RH thumb throttle, I used it on the LH NC
    Gear Sensor for casette gears 45.00
    Magnetic Brake Sensors NC
    BB Luna Wrench 19.00
    Advanced 300 watt Luna Charger 79.95
    Luna Eclipse 42t chainring in black 99.95
    Mighty Mini Cube 52v 6ah 30Q 299.95
    (2) yellow plug 40" extension cables 39.90
    Misc. wiring & connectors, and wire strip tool 41.24
    More Misc. wiring and shrink tube 14.05
    Shipping 60.00
    2nd Shipping 7.00
    Total Cost 1,420.04
    In conclusion, I now have a motorized trike that is more powerful than I need, faster than I expected, and I am absolutely delighted with it. A plus is that I saved lots of money buying my kit and battery from Luna, and I have the satisfaction of knowing I did the work myself.

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    Attached Files
    Last edited by SARose; 09-22-2016, 10:44 AM.

    You're a pretty awesome lady, SARose! Keep it up! Great write-up and awesome to see more recumbent trike riders. here.


      Wow thanks for this. I want to do a trike soon.


        Cool trike, I haven't seen a Scarab/Greenspeed in several years. Looks like it's been very well maintained. What a great write-up.
        72-year-old grandpa here and made my first around the block test ride last night before dark on my TerraTrike Tour with BBS02 750w and 52v battery. I'm waiting on a few bits and pieces to finish my installation.


          Wow, you sure aren't the typical grandma, super cool! Love that bike, and your write-up is just excellent. So glad you found the forum here, and jumped right in.

          Ramps, and carrying the bike inside the wagon, looks like a real good transport solution, too. Only with a trike....

          Welcome, and happy riding to you!
          Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.


            Welcome SARose. Outstanding writeup!


              Just about to build one for my wife, Trike should arrive tomorrow (New Greenspeed Magnum XL) Luna Kit has already arrived. Thanks for this it has really helped me know what to get. Cant wait.


                Very awesome! Thanks for taking the time to write all of that out.


                • Nick R.
                  Nick R. commented
                  Editing a comment
                  OH WOW, you have really motivated me to do the same with my Catrike Expedition, At 88 yrs old I have a few years on you but you did show me the way. Living in Florida my needs won't be as much as yours so I hope to do the same with a smaller motor. All the best. Nick R.

                WOW, I’m impressed ... that is a LOT of motor, especially with a 52v battery ... I put a BBS02 on my trike, with 48v, and thought that was fast


                  Hey SARose, if you see a notification for this, drop in and say hi, and tell us how it's going. You built a fast trike, and disappeared....I hope it all went well after that! :)
                  Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.


                    Very nice write-up!
                    We used to live in Texas and often traveled to San Antonio to ride - a pair of HPV Scorpion FS26's.

                    Retiring in Tucson the hills are a bit more intense making boost a necessity. Played with several systems to find the right one.

                    The Bafang BBS02 was pretty good but not ideal for us. Just a bit too strong for the SRAM DD3. Cadence PAS took a while to get comfortable with shifting. Very efficient though.


                    Also tried the TSDZ2 Mid Drive. Lowest cost and weight system, but quality suffered. Ours was pretty noisey and without power had a lot of drag.


                    Tried a few Direct Drive motors but not a good match for us. Trikes typically run in the 10-12 MPH range below the efficiency zone of DD motors. Long climbs tripped fold-back safety cutting power. Also drained batteries about twice as fast as the Mid Drives.

                    Then we tried the MAC 10T Cassette geared hubmotors. Used the CA3 as a computer and the Thun Torque Sensing bottom bracket for PAS and a throttle. A variable PAS dial allows PAS to be set at 0-10X rider input power, and as a bonus it measures rider input in watts. Simply a superb system, climbs anything. Very efficient. With motor off, no added drag.


                      Hey Rose,

                      For what distance do you think your rig could sustain 28 miles per hour with a 17 amp hour battery? I'm thinking of picking up a couple of chromoly gt3s on the used market and dropping in some bafang motors.



                        If you click on the persons name under their avatar you can see when they were last online to get an idea how good a chance you have of getting a reply to an old thread, Rose hasn't been on the site since 2018 so I would not get my hopes up too much on getting a reply. Looks like she did a pretty detailed write up which is nice to see so there is a ton of good info for someone with a similar rig.


                          Nice. Commenting so I can find this later.


                            I just purchased this trike from the former owner who wrote this article. It is in fabulous condition for a 18-19 year old trike and the e-assist is still fully functional and really fun! I have only had it a few days, but I know I have many fun miles ahead! Also, because of my researching this purchase, I am in touch with the builder of these trikes. He has answered my many questions, sent me a copy of the original owner's manual and is so excited that the trike is still in good condition and being enjoyed.