Hi all,
currently i'm using a bafang bpm "500w" hub motor on my rocky mountain flatline park
i just found here on ES a guy who developed a kit to mount this exact motor as mid drive ( http://endless-sphere.com/forums/viewtopic.php?f=28&t=63429 )
until i get my kit it will be about 2 months, and until then i want to figure out what would be the most efficiant way to mount it, to get as much speed and power as possible.
right now, as a hub motor with a 48v battery and a 34a (peak) controller i get to 53kmh on flats, and i wish to get at least this (if not more) when mounted as mid-drive.
i currently have 2 plans -
1) a chain from the motor (with 14t sprocket) to a double crank w\freewheel, and from the crank to the normal bike speeds at the back wheel, something like that -
View attachment 1
2) a "double chain system" - keep the crank the way it is, and add another big sprocket at the back, with seperated chain just for the motor -
The thing is - i never built a mid drive system and im not too good with ratio calculations :| so i wish you guys would help me decide which way would be better, and what sprockets should i use (for option 1 i need to change the crank sprocket and for option 2 the big back wheel sprocket), assembly for both options are prettly simple for me, option 2 is even easier for me to make, so no help needed here, just with the ratios
hope i made myself clear allthough my english is lousy lol
hope for answers, Noam.
currently i'm using a bafang bpm "500w" hub motor on my rocky mountain flatline park
i just found here on ES a guy who developed a kit to mount this exact motor as mid drive ( http://endless-sphere.com/forums/viewtopic.php?f=28&t=63429 )
until i get my kit it will be about 2 months, and until then i want to figure out what would be the most efficiant way to mount it, to get as much speed and power as possible.
right now, as a hub motor with a 48v battery and a 34a (peak) controller i get to 53kmh on flats, and i wish to get at least this (if not more) when mounted as mid-drive.
i currently have 2 plans -
1) a chain from the motor (with 14t sprocket) to a double crank w\freewheel, and from the crank to the normal bike speeds at the back wheel, something like that -
View attachment 1
2) a "double chain system" - keep the crank the way it is, and add another big sprocket at the back, with seperated chain just for the motor -
The thing is - i never built a mid drive system and im not too good with ratio calculations :| so i wish you guys would help me decide which way would be better, and what sprockets should i use (for option 1 i need to change the crank sprocket and for option 2 the big back wheel sprocket), assembly for both options are prettly simple for me, option 2 is even easier for me to make, so no help needed here, just with the ratios
hope i made myself clear allthough my english is lousy lol
hope for answers, Noam.
