Decided to make an electric tandem for my wife and I. We plan on using it to get us around town with little effort. My wife has bad knees and I’m not getting any younger so I decided electric was the way to go.
I have never owned or even ridden a regular tandem so I relied on forum member’s posts and the Paterek manual. Space is a premium at my place so I decided on 20” wheels to keep the overall length of the bike shorter.
First, I needed a tandem frame jig. I decided to manufacture a Cobra frame jig clone. Joe at Cobra is great at describing how he designed his jig and his videos helped a lot. I do not believe my home made tandem jig is anywhere near as good as a Cobra but good enough for my hobby needs.
I built the front and rear triangles in my Anvil jig and then used my home made tandem jig to connect the front and rear together.
The bike is complete and we have used it a bunch of times so far without any issues.
Wow, what a machine! I love big bikes with small wheels
Is there a specific reason why you didn’t mount the two cranksets in sync with one another? I also haven’t got a clue about tandems but I think they usually have the cranks in sync…
The front crankset has a freewheel in the spider. This allows the captain to stop pedalling while the stoker can continue to pedal. When I first built up the bike for a test ride, I found it annoying that if the stoker was pedalling going into a turn, I had to pedal when them. Ideally there should be a freewheel in the stoker’s crank as well so that the two cranks are completely independent allowing either rider to stop pedalling.
It’s a personal preference but I really like that when sitting up front, I can stop pedalling while the person behind pedals blind. The best part about riding an ebike is that pedalling is optional.
I’ll try to post some closeups of the freewheel cranks.
I used a flanged freewheel and adapted it to work with an inexpensive square taper Shimano crankset. Removed the stamped steel chainrings and machined/threaded the right crank arm to accept the flanged freewheel thread. I also made an adapter that allowed a 110bcd narrow/wide chainring to bolt up to the flanged freewheel.
