Hello All,
I recently built and toured on the Viking Tandem Trike. While I love it, the hills in Maine really killed my legs and so I am looking to add an electric motor to the trike. The motor would be used primarily for hill-climbing assistance. Given the demands on the wheels (and the requirement for 14mm axles), it seems that a mid drive motor makes the most sense. After research, the Bafang BBSHD seems to be the motor of choice for performance and reliability. My question, however, is how to tie it in to the Viking's complicated drive system?
My first instinct would be to place the motor in front for the pilot. This would allow the motor to have access to the gears on the rear cassette (helpful for hill climbing torque). However my concern is that this would wreak havoc on the stoker's pedaling cadence, causing them to spin out of control. This could be compensated for with a larger left side chain-ring, but I already have a 46t chain-ring on the left and hesitate to go any larger as I want the trike to function well even without the motor running. While perhaps spin-out would not be an issue if the motor is used to assist with hill climbing only, I wonder if anyone has any thoughts on these dynamics? Is the solution as simple as simply restraining the impetus to 'throttle up?'
Were the motor to be placed within the stoker's BB, the problem then is that there is not room for a left-side chain-ring. One could maybe move the chain-ring way out but then the chain-line on the left would be totally out of wack (I already broke two freewheels due to a misaligned left chain-line and want to avoid breaking a third). Maybe this could be solved by extending the crossover dropouts but unfortunately my access to a welder has ended.
This Viking will be my daily vehicle on a very hilly island and I plan to haul heavy cargo, so the motor is a necessary addition. An ideal situation would consist of a 15-18mph cruising speed with a comfortable cadence for both stoker and pilot while also being able to climb up steep hills over longer distances (no single-track level grades). The trike is close to doing this as is but we pushed it up several hills on the last trip and are looking to avoid this moving forward. Any thoughts or experience is appreciated.
Best,
Nathaniel
I recently built and toured on the Viking Tandem Trike. While I love it, the hills in Maine really killed my legs and so I am looking to add an electric motor to the trike. The motor would be used primarily for hill-climbing assistance. Given the demands on the wheels (and the requirement for 14mm axles), it seems that a mid drive motor makes the most sense. After research, the Bafang BBSHD seems to be the motor of choice for performance and reliability. My question, however, is how to tie it in to the Viking's complicated drive system?
My first instinct would be to place the motor in front for the pilot. This would allow the motor to have access to the gears on the rear cassette (helpful for hill climbing torque). However my concern is that this would wreak havoc on the stoker's pedaling cadence, causing them to spin out of control. This could be compensated for with a larger left side chain-ring, but I already have a 46t chain-ring on the left and hesitate to go any larger as I want the trike to function well even without the motor running. While perhaps spin-out would not be an issue if the motor is used to assist with hill climbing only, I wonder if anyone has any thoughts on these dynamics? Is the solution as simple as simply restraining the impetus to 'throttle up?'
Were the motor to be placed within the stoker's BB, the problem then is that there is not room for a left-side chain-ring. One could maybe move the chain-ring way out but then the chain-line on the left would be totally out of wack (I already broke two freewheels due to a misaligned left chain-line and want to avoid breaking a third). Maybe this could be solved by extending the crossover dropouts but unfortunately my access to a welder has ended.
This Viking will be my daily vehicle on a very hilly island and I plan to haul heavy cargo, so the motor is a necessary addition. An ideal situation would consist of a 15-18mph cruising speed with a comfortable cadence for both stoker and pilot while also being able to climb up steep hills over longer distances (no single-track level grades). The trike is close to doing this as is but we pushed it up several hills on the last trip and are looking to avoid this moving forward. Any thoughts or experience is appreciated.
Best,
Nathaniel