Mid-drive using bb as jackshaft w one-way bearing?

closest i can find is this:
https://lunacycle.com/luna-tick-crankset-for-mid-drives/

but to have the jackshaft aspect would need be more complicated. i think theres nothing out there and will have to design and get it made. what out there is a good example of such a bottom bracket/crankset?

I’ve been using the GNG cyclone bracket and freewheel for a while. Mechanics are good with isis crank and decent bearings. Sprockets are pretty average tho.

https://www.gngebike.com/freewheel-crank

Can you clarify what you are looking for? If it is a crank freewheel with two chainrings you are looking for I'm using one of these HD freewheels: http://sickbikeparts.com/front-freewheel-heavy-duty/ and "Cyclone" crank arms from the same site. For the chainrings, I'm using something like this from the motor to the crank/BB: http://sickbikeparts.com/chainring-freewheel-40-tooth/ with some longer bolts and spacers to connect a generic 104BCD chainring from the crank/BB to the rear wheel sprocket.

Looks like this:

Yes like your picture. Thanks. i now see in the pic the jackshaft done with the two chainrings on the same side. easier, cheaper, and better than what I was thinking. My mind has melted.

hard to get to a 12:1 gearing

it would be a lot of work but the best way I can come up with to get a 16 tooth "chainring" on those cranks with the other chainring being a high tooth count would require taking this apart, milling teeth off a row of teeth and then welding another row on. otherwise limited to 24 teeth http://sickbikeparts.com/chainring-freewheel-24-tooth/

really i was planning to use pulleys and a belt coming from the motor and id weld that pulley to the other side of the freewheel.

and with a standard freehub body and aluminum cog i can get 50 teeth.
https://www.ebay.com/itm/333589488821?chn=ps&norover=1&mkevt=1&mkrid=711-213727-13078-0&mkcid=2&itemid=333589488821&targetid=4581183927179149&device=c&mktype=&googleloc=&poi=&campaignid=418233787&mkgroupid=1241348861725295&rlsatarget=pla-4581183927179149&abcId=9300542&merchantid=51291&msclkid=eaddb2528064175d5b66d2884a9efb24

The problem with doing a 12:1 gearing this way is that your jackshaft will be spinning at a couple thousand rpm which means you won't be able to add anything with your legs since human legs can only do about 100rpm.

thepronghorn said:

The problem with doing a 12:1 gearing this way is that your jackshaft will be spinning at a couple thousand rpm which means you won't be able to add anything with your legs since human legs can only do about 100rpm.

Click to expand...

thats fine i plan to only pedal if i run out of batteries.

going from the cranks to the rear i can only get 24:50.... only about 1:2.

from the motor to the cranks ill get those two pulleys made. If i can get 4:1 there ill call it good enough and use the smaller 24" wheels on a 26" frame. think that shouldnt be a problem. will use a chain half link or maybe a slightly smaller cog in back to get a tight fit.



what you think of using a standard freehub body and single aluminum cog in the back? Im trying to find the strongest freehub body to use. will do 90 amps max.
https://www.ebay.com/itm/333589488821?chn=ps&norover=1&mkevt=1&mkrid=711-213727-13078-0&mkcid=2&itemid=333589488821&targetid=4581183927179149&device=c&mktype=&googleloc=&poi=&campaignid=418233787&mkgroupid=1241348861725295&rlsatarget=pla-4581183927179149&abcId=9300542&merchantid=51291&msclkid=eaddb2528064175d5b66d2884a9efb24