nesdon
10 mW
My full time job is taking care of my toddler granddaughter. When she was little, I used a Bobike front seat, 
which she absolutely loved, but she aged out of it and I had to convert to a rear seat. But I quickly realized it was very hard to get on an off without throwing my leg over the back, especially with her weight in the seat.
After I had a double knee replacement, I had wanted to convert that wonderful Trek Soho with its Nexus 8 IGH and Gates Belt drive, to a Bafang mid-drive ebike, but the belt line, especially on the older non-CDC design, is much more critical than a chain line, so I hesitated, expecting that I was going to have to fabricate offsets to keep the belt on. BTW, belts are the future, so superior to chains.
Once I realized how hard it was to use with her on the back, I recalled an old ladies Townie 3s ladies I had bought my now deceased sister, and had it shipped to me. It's ideal for the kids seat issue, and seemed like a good candidate for a conversion. I opted for a 48V 750W Tongsheng TSDZ2his, but was unsure where to mount the battery on this frame, especially since with mail order I was not able to check the fit. I opted for a 14.5 Ah Hailong Shark style with Samsung cells.
The Townie had a coaster brake with a 3 speed Nexus, but discovered that coaster brake motors were limited to 36V or 500 W, so decided to use the time i had to wait for the shipping from China to rebuild the wheel with used Nexus 8 hub I got on ebay for $50. The seller had dozens, which, for a hub that's over $200 new, were suspiciously cheap but which think may have been pulled from a fleet of a failed city bike program. It works flawlessly, and the guts are in excellent shape. The behavior of the motor has made me feel that a 3 speed would probably have been enough, as I don't need to shift as much with the torque assist.
Turned out the battery would not fit between the double downtube as I had hoped, so I installed some rivnuts and attached a piece of aluminum U-Channel to mount it above the top downtube. It worked but raised the step-over higher than I would have liked, so I eventually severely modified the shark case to get it to go in the space between the tubes.
I removed the base section and used a heat gun to put a dimples in both the nose and the rear of the case. It makes it hard to remove, but I have an outlet where I store my bikes, so easy to recharge in place. It also required that I remove the LED charge level indicator, but the 850c display shows more than enough battery info. The narrow front dimple engages a little gusset between the head tube and the top downtube (tho Electra no longer uses these).
The rear dimple nestles into the bottom of the frame. I hold it up with a quick release strap, carved some ethafoam blocks to help locate the bottom, and added a small section of doubled 1/16" x 3/4" aluminum angle held to the lower tube with a hose clamp to hold it forward and engaged in the gusset dimple. I thought I would add a heavier angle stop with rivnut to replace this, but it works perfectly and is subtle enough that I'll leave it.
I also installed the Open Source Firmware on the 850 C display as well as a thumb throttle, but not brake or shift cutoffs. The one issue with the firmware I haven't figured out is that theres a bit of a long delay as the power ramps up aftre I start pedaling. This is an issue when down shifting in the middle of a hill climb, where you're suddenly stuck with no assist for a few revs. Any tips on what to change to reduce this power lag. An old man on a ladies bike with a toddler on the back is not going to be doing any hotrodding, so I don't think I have to worry about over-stressing the drive gears.
We are both loving it!
which she absolutely loved, but she aged out of it and I had to convert to a rear seat. But I quickly realized it was very hard to get on an off without throwing my leg over the back, especially with her weight in the seat.After I had a double knee replacement, I had wanted to convert that wonderful Trek Soho with its Nexus 8 IGH and Gates Belt drive, to a Bafang mid-drive ebike, but the belt line, especially on the older non-CDC design, is much more critical than a chain line, so I hesitated, expecting that I was going to have to fabricate offsets to keep the belt on. BTW, belts are the future, so superior to chains.
Once I realized how hard it was to use with her on the back, I recalled an old ladies Townie 3s ladies I had bought my now deceased sister, and had it shipped to me. It's ideal for the kids seat issue, and seemed like a good candidate for a conversion. I opted for a 48V 750W Tongsheng TSDZ2his, but was unsure where to mount the battery on this frame, especially since with mail order I was not able to check the fit. I opted for a 14.5 Ah Hailong Shark style with Samsung cells.
The Townie had a coaster brake with a 3 speed Nexus, but discovered that coaster brake motors were limited to 36V or 500 W, so decided to use the time i had to wait for the shipping from China to rebuild the wheel with used Nexus 8 hub I got on ebay for $50. The seller had dozens, which, for a hub that's over $200 new, were suspiciously cheap but which think may have been pulled from a fleet of a failed city bike program. It works flawlessly, and the guts are in excellent shape. The behavior of the motor has made me feel that a 3 speed would probably have been enough, as I don't need to shift as much with the torque assist.
Turned out the battery would not fit between the double downtube as I had hoped, so I installed some rivnuts and attached a piece of aluminum U-Channel to mount it above the top downtube. It worked but raised the step-over higher than I would have liked, so I eventually severely modified the shark case to get it to go in the space between the tubes.
I removed the base section and used a heat gun to put a dimples in both the nose and the rear of the case. It makes it hard to remove, but I have an outlet where I store my bikes, so easy to recharge in place. It also required that I remove the LED charge level indicator, but the 850c display shows more than enough battery info. The narrow front dimple engages a little gusset between the head tube and the top downtube (tho Electra no longer uses these).
The rear dimple nestles into the bottom of the frame. I hold it up with a quick release strap, carved some ethafoam blocks to help locate the bottom, and added a small section of doubled 1/16" x 3/4" aluminum angle held to the lower tube with a hose clamp to hold it forward and engaged in the gusset dimple. I thought I would add a heavier angle stop with rivnut to replace this, but it works perfectly and is subtle enough that I'll leave it.
I also installed the Open Source Firmware on the 850 C display as well as a thumb throttle, but not brake or shift cutoffs. The one issue with the firmware I haven't figured out is that theres a bit of a long delay as the power ramps up aftre I start pedaling. This is an issue when down shifting in the middle of a hill climb, where you're suddenly stuck with no assist for a few revs. Any tips on what to change to reduce this power lag. An old man on a ladies bike with a toddler on the back is not going to be doing any hotrodding, so I don't think I have to worry about over-stressing the drive gears.
We are both loving it!
