Kick bike motor advice needed please

Jbern

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Jun 21, 2021
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I would appreciate some advice about the best type of hub motor for my project. I’m converting a full suspension Kick Bike to use as a “sporty” mobility device.

(I’m posting this here because the kick-bike is basically a bicycle frame with 20” wheels and the standing scooter section seems to deal more with scooters with small wheels.)

I’m going to attach a seat and will alternate standing/sitting.

Needs:
- The rear spacing is only 100 mm so I’ll need to use a front motor in back. (20” wheels)
- no need to go above 20 mph.
- need to be able to climb short, but potentially steep hills as I ride around local parks, and on bike trails.
- ideally, would like to use the 12s Lipo packs I have on hand (around 50v fully charged).
- need a reliable system as I am limited in my ability to walk back to the car in the case of a breakdown.
- I’m 170 lbs and total riding weight of myself and scooter will be 240-250 lbs depending on motor choice.

My first thought was the ideal motor might be something like a 10T MAC or BMC but neither appear to be available anywhere.

Questions:
1. Geared or DD?
2. If geared (and considering no MAC/BMC available), any suggestions?
3. If DD, any suggestions for a lower speed, higher torque motor that could occasionally handle lots of phase amps(?) to get 250 lbs (total) up short hills at slower speeds?

I realize I could just grab a cheap option like something off Amazon/Ebay, or an Ebikeling 500w geared (which, sounds like is probably a true 350w) and just make do. However, given my need for reliability and ability to get me up short hills (without having to race up it at max speeds), I’m wondering if something cheap will leave me needing more power (or in the worst case, stranded).

This will mostly be for gentle cruising around and getting myself out in the sun each day. That said, when I need to power up a short, (but steep )hill at 10 mph I’d like to avoid burning up my system.

Very grateful for any thoughts.
 

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I've seen a few kick bike builds on the forum, but can't seem to find many of them right now, but here are a few. Perhaps they may have to useful info:

https://endless-sphere.com/forums/viewtopic.php?t=101271
https://endless-sphere.com/forums/viewtopic.php?t=79807
https://electricbike.com/forum/forum/main-forum/diy-discussion/71337-building-a-adult-%E2%80%9Ckickbike%E2%80%9D-%E2%80%9Ckickscooter%E2%80%9D-with-only-china-parts-total-noob
 
The 20" wheels will beef up whatever motor you put in, so there's no need to use a big/heavy/expensive motor like MAC. A salvaged Bafang hub motor from JAG35.com would be a good match for what you're doing here, if you run it on 48 volts with a 20-22 amp controller.

The weight distribution of a scooter like that means that you can use a front or rear hub with equally satisfactory results. Rear motor would be a little more tractable on loose surfaces, but front motor would be more maneuverable because it will positively pull in the direction you steer it. If you want serious hill climbing ability and some mechanical redundancy, you could use two motors.

I would want to use a geared hub, to allow the scooter to coast freely.
 
Where you are matters some. In the USA or canada, there are kit vendors that could supply a mac 10t, or a motor nearly identical to it in a front wheel kit, 100mm spacing, with disc brake mount.

That would be my choice, but a DD motor would work too. You could buy any cheap kit, and then relace it to 20" wheel, using spokes and rim that fit from a vendor like Grin Technology.
 
Thanks for the responses and insights. Chalo’s suggestion about Jag.35’s salvaged Bafang kits was very intriguing but unfortunately their front kits are 26” and I need 20” (I have no experience lacing motors). Dogman, I would LOVE to get my hands on a MAC/BMC in a 10T as that would give lots of headroom if I needed more power down the road. Unfortunately they seem to be unavailable everywhere I’ve looked (unless you guys know of a place to get them that I haven’t seen yet?).

My options seems to be:
1. Grab an Ebikeling 500w geared kit or a 1000W DD. (I assume the geared kit (small as it is) would be better for my needs of <20 mph and short hills?)
2. Spend a ton of money on an Ezee geared motor + controller from Ebike.CA.
3. Wait (potentially a long time) for a MAC or BMC to become available.

I’ve researched Ebikeling kits but don’t yet have a sense of whether their geared motors (which appear to be mid-sized) at 48V and 20 amps will have enough power to move 240 lbs total weight up short but steep hills. Do you guys have any insights?

(It seems to me that worst case if I get something budget now, and later find a MAC/BMC, I could put the budget motor on the front and the MAC/BMC on the rear and, like Chalo has suggested, have dual motors. Plenty of power to climb anything, and redundancy in case one fails so at least I can make it back to the car. My scooter has front shocks but they are steel and I figure as long as I don’t go over 700w(?) on the front - and use dual torque arms - I should be ok.)

Again, very grateful for any thoughts/insights.
 
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