Tandem electric assist

[huffinandpuffin]

Hello. My first post here. I am planning to convert a tandem, placing Bafang motor at captain’s position. I intend to connect motor to stoker’s cranks with one of the three chainrings on a triple crank, and still use the other two rings with front derailleur. Any thoughts? Will this even work? Will I need two gear sensors? Also hoping to keep my road bars and levers. Has anyone had experience with cut-off switches on road brake levers? I guess there's always the back-pedal option.

 

[Chalo]

You'll probably have issues with the front derailleur fouling the timing chain. To avoid that problem, you'll have to space the timing chainring way out from its usual position, while keeping it aligned with the front chainring. Given the weird wide chainline of most Bafang BB motor setups, that pretty much implies the timing chain takes the outer position and the shiftable rings are inboard. You can space the outer ring outward or both the inner rings inward, or a little of both.

 

[huffinandpuffin]

Thank you for your quick reply. I planned to set up the chainrings as you suggest (timing chain outside). Will have to play around with the spacing. Any thoughts on the brake levers?

 

[Chalo]

Any thoughts on the brake levers?

Probably reed switches and magnets on your current levers would be least disruptive. I'm not aware of any drop bar levers with switches.