mechhead
10 W
H all im new here but have been avidly reading endless sphere stuff for a long time
I would like to start a thread for a community developed opensource high quality mid drive kit that may incorporate regenerative breaking and is designed around the newly available agricultural drone pancake motors
I will start with a problem statement that outlines the short comings of many of the current mid drive units.
problems with currant mid drive setups; weight and quality of existing kits, motors need to be large and heavy to deal with low reduction ratios, or for the rc motors and astros, need high reduction ratios to make effective torque at crank speeds, or direct drive through seperate chain system lacking gears and compromising efficiency at low or high speeds and also lack implimentation of regenerative breaks
I like the idea of very light motors and drive trains that see the existing bike gears, it saves weight and increases efficency and for the real world makes towing cargo or children and dogs easy and still has long legs for solo missions
Enter the new class of motor that no one on here is talking about yet that IMHO holds the most promise of efficency/light weight and needing minimal reduction.
the drone pancake motors, i have ordered a smaller one to play with and test out, specs are 100kv 83/18mm stator 2.7kw 180second rating 48 poles efficient rpm band 500 to 7000 T-motor do some nice ones a u12 and u13 109mm dia by 40mm long and 118mm dia by 56mm long with the u13 rated at 3100watts 180 second . the power ratings are probably on the high side for a bike motor as the airflow cooling they experience turning a 25 to 30 inch props on a large drone is would mean very large cooling airflows. With more conservative power levels should be good for a bike drive. the best reduction would seem to be small chain (efficent, strong but noisey with lots of sprocket options) belt drive (quiet and efficent but less ratio options or precision planetary gearhead ie neugart parker apex etc (quiet, strong and efficent, fixed ratio, more compact than either belt or chain but possibly heavier) i like the planetary solution because it is so compact and potentially long lasting and with one of these axially short drone motors easy to fit between crank arms.
The pancke motors main advantage over other rc motors or astros is their low rpm efficency from the huge pole count and large diameter, if you go look on alienexpress there are heaps of different kinds to choose from.
Implimenting regen
This could be done using a friction roller on an arm that pivots about the motor axis and contacts the tyre spinning the motor backwards. the rotation being opposite when in breaking mode to driving mode allowing the reduction stages to be bypassed this would be easy to impliment with either a belt or chain drive but more difficult with a planetary setup but still could be done by diving the other end of the motor shaft. this system would allow a regenerative break with a mid drive as all reduction would freewheel in reverse.
for smaller power levels the reduction could be done with 1/4" chain driving a large sproket that mounts inside of the triple chain rings it would be similar size as the smallest 28 to 34 tooth sproket on the inside of the chain ring setand would need to be cantilever mounted to fit around the BB there is room for a sprocket for this chain size between the front derailer and the frame on many bikes and it would look stealthy hiding behind the chain wheels just above the bottom bracket where on the other side there is room for the other stage of reduction and a regen arm and roller that engages the rear wheel with a cable paired to the rear brake.
I can picture an extended shaft on the pancake motor that drives a planetary gb through the motor base and a small tooth belt or chain sproket on the other side(left) of the motor and planetary box that goes to the arm that carries the wheel breaking roller.
for minimal power levels 200 to 750watts a 50mm planetary gb could be used, for higher power levels a larger 60 or 80mm planertary box would be needed
due to the low reduction requirements 10:1 planetary single stage and 2:1 to 4:1 final small chain drive of chain rings. there are several neugart threads already but there are many other high strength precision planetaries to choose from although none of them are cheap although there are many choices of used ones on ebay .
A 10:1 planetary and 3:1 final drive would give 30 :1 total reduction to the chain rings making 2700rpm motor to 90 rpm pedals
any feedback would be welcome
I would like to start a thread for a community developed opensource high quality mid drive kit that may incorporate regenerative breaking and is designed around the newly available agricultural drone pancake motors
I will start with a problem statement that outlines the short comings of many of the current mid drive units.
problems with currant mid drive setups; weight and quality of existing kits, motors need to be large and heavy to deal with low reduction ratios, or for the rc motors and astros, need high reduction ratios to make effective torque at crank speeds, or direct drive through seperate chain system lacking gears and compromising efficiency at low or high speeds and also lack implimentation of regenerative breaks
I like the idea of very light motors and drive trains that see the existing bike gears, it saves weight and increases efficency and for the real world makes towing cargo or children and dogs easy and still has long legs for solo missions
Enter the new class of motor that no one on here is talking about yet that IMHO holds the most promise of efficency/light weight and needing minimal reduction.
the drone pancake motors, i have ordered a smaller one to play with and test out, specs are 100kv 83/18mm stator 2.7kw 180second rating 48 poles efficient rpm band 500 to 7000 T-motor do some nice ones a u12 and u13 109mm dia by 40mm long and 118mm dia by 56mm long with the u13 rated at 3100watts 180 second . the power ratings are probably on the high side for a bike motor as the airflow cooling they experience turning a 25 to 30 inch props on a large drone is would mean very large cooling airflows. With more conservative power levels should be good for a bike drive. the best reduction would seem to be small chain (efficent, strong but noisey with lots of sprocket options) belt drive (quiet and efficent but less ratio options or precision planetary gearhead ie neugart parker apex etc (quiet, strong and efficent, fixed ratio, more compact than either belt or chain but possibly heavier) i like the planetary solution because it is so compact and potentially long lasting and with one of these axially short drone motors easy to fit between crank arms.
The pancke motors main advantage over other rc motors or astros is their low rpm efficency from the huge pole count and large diameter, if you go look on alienexpress there are heaps of different kinds to choose from.
Implimenting regen
This could be done using a friction roller on an arm that pivots about the motor axis and contacts the tyre spinning the motor backwards. the rotation being opposite when in breaking mode to driving mode allowing the reduction stages to be bypassed this would be easy to impliment with either a belt or chain drive but more difficult with a planetary setup but still could be done by diving the other end of the motor shaft. this system would allow a regenerative break with a mid drive as all reduction would freewheel in reverse.
for smaller power levels the reduction could be done with 1/4" chain driving a large sproket that mounts inside of the triple chain rings it would be similar size as the smallest 28 to 34 tooth sproket on the inside of the chain ring setand would need to be cantilever mounted to fit around the BB there is room for a sprocket for this chain size between the front derailer and the frame on many bikes and it would look stealthy hiding behind the chain wheels just above the bottom bracket where on the other side there is room for the other stage of reduction and a regen arm and roller that engages the rear wheel with a cable paired to the rear brake.
I can picture an extended shaft on the pancake motor that drives a planetary gb through the motor base and a small tooth belt or chain sproket on the other side(left) of the motor and planetary box that goes to the arm that carries the wheel breaking roller.
for minimal power levels 200 to 750watts a 50mm planetary gb could be used, for higher power levels a larger 60 or 80mm planertary box would be needed
due to the low reduction requirements 10:1 planetary single stage and 2:1 to 4:1 final small chain drive of chain rings. there are several neugart threads already but there are many other high strength precision planetaries to choose from although none of them are cheap although there are many choices of used ones on ebay .
A 10:1 planetary and 3:1 final drive would give 30 :1 total reduction to the chain rings making 2700rpm motor to 90 rpm pedals
any feedback would be welcome