Adding hub motor to yuba mundo bbhd

[newjazz]

Hello, i recently added a bafang bbshd to my yuba mundo v3. My question is, what could i expect if i went ahead and add a mxus or leaf 1500? My goal is to improve torque or punch from zero. I live in paris france and i almost always am loaded down with an 18 pound amplifier and two instruments for 40 lbs total. i am really satisfied for the most part but, it would be nice if i can avoid the shifting time from a red light. My idea is to use the throttle of a hub motor get me up to speed then switch over to the bafang to cruise.
Being a jazz musician i am usually not one to accept limitations besides, i dont want to go with all the limitations and hassles of a scooter..... Any suggestions would be greatly appreciated

 

[amberwolf]

You'll probably get better launch torque out of the BBSHD thru your lowest gear than you will out of a DD hubmotor, unless you are pouring quite a bit of power into the hubmotor. Your battery will have to be able to output that power; if it can't you then need a battery for that purpose, as well as the new motor and controller, all of which will add even more weight to the bike.


FWIW, if you look at CrazyBIke2 as it is now (last pages of the thread linked in my signature), I have two DD hubmotors, total around 4KW, gets me from 0-20MPH in around 4 seconds or less.

But it would probably take less power if I had that thru the drivetrain and could downshift to a low gear first, and then shift up thru the gears as needed to get to speed.

The best compromise (for my purposes, and probably yours) would be the existing middrive thru a 3-speed IGH in the rear wheel (or as a jackshaft), because itw ould be faster to shift thru the gears (being only 3 of them) and no worriesa bout derailing the chain, etc., though you'd still have to back off the power during each shift.

 

[dogman dan]

I'd add a geared motor, because when you cruise on the DD, it will be resisting. A geared motor will freewheel when running on just the BB.

I'd also be inclined to make that motor a front motor, so you don't twist the gears right off the motor cover, on a rear motor.

You could use a doorbell button on the left side, to turn on and off the hub motor. So when you mash the button, the hubbie would get the same signal the throttle is giving.

Then you can leave the bb in a high gear, and at a stop, mash the button. Then when you want to go, both hub motor and bb will pull. once up to speed, let off the doorbell or horn button to shut down the geared motor.

It could also work the reverse way, running most of the time on the hub motor, and using the doorbell to kick on the BB. That is how you would want to run if you added a direct drive hub motor.

 

[newjazz]

HEY THANKS! I guess it need to think about a geared hub motor since a DD would have some drag. Oh, forgot to mention I built my battery pack It's a 30q 13s 7p seems to be working pretty well, no problems there. noticed today while making a supermarket run that my bike has noticeably more pep without the extra 50lbs of music stuff.
Hey what if I built a 14p pack with more 30q Samsungs?

 

[newjazz]

Dam I forgot about the possibility of hacking my bbsHD? WOULD that solve my take off problem without frying my motor?