Technical advice on proposed eMTB build

[jmaikido]

Hi folks,

I'm looking to purchase a relatively inexpensive hardtail MTB .... not fussed on size, but perhaps 27.5". I'm 6' tall and have previously added a mid-drive motor to a 26" dual suspension Cannonade MTB. Without going into details, the bike was stolen sometime ago and I'm now considering a rear hub motor conversion to a hardtail. (Mainly b/c I rarely used the rear suspension). My cycling is solo rides on w/e, occasional commutes to work (on bitumen/gravel roads) and long term proposal to ride on fire-trails and 'rail trails' (converted disused railway corridors)

I'm looking at a 2000w rear hub motor, something like:
https://www.aliexpress.com/item/32268426912.html
This kit comes with 72V 35A/40A smart controller (listed on the ad)

After a bit of hunting around I came across a 72v downtube mount battery (since I want to mount the battery on the downtube).
https://www.ebikes.ca/shop/electric-bicycle-parts/batteries/b7210li-dt.html

Not having done this before, I'm seeking some technical advice on my 'project'

Such as:

Is the battery suitable for the hub kit I'm looking at?
Since the battery is only available for local pickup, (and I'm in Australia), where could I go to acquire such an item?

Maybe there's someone who could recommend a similar total solution?
eg. bike/kit/battery
or kit/battery for either 26/27.5" mtb

Regards,
John

 

[dogman dan]

The battery would be happier pulling 30 amps, vs the 40 amps controller you are looking at. However, most of the time you will not pull much more than 15 amps.

At 72v, the 30 amps will be plenty, 2000w. You should have about 35 mph top speed, and plenty of power on hills. I used to do a lot of hard riding on 72v 20 amps in summer, because I was using smaller motors, and 2000w would kill them in summer. I had no battery limitations though, I had batteries able to put out 100 amps.

Again, though you could do what you propose, I would want to find a lower amps controller. Batteries are the huge expense of e bikes, and you should go easy as you can on them.

Re the bike, screw 27.5 inch. Harder to find tires, and motor wheels. 26 is fine.