Hub motor kits specifically for mopeds?

General Discussion about large electric scooters and motorcycles and other things with no pedals.
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NewbieUser   10 µW

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Joined: Nov 24 2019 8:33am

Hub motor kits specifically for mopeds?

Post by NewbieUser » Jan 11 2020 7:52am

Hi all-

Still completely new to this, trying to find the best options for my needs. I was looking at fat tire bikes, but am now leaning back toward a moped conversion. I can get a used moped in my area for anywhere from $150-250 as my starting point. I think the mopeds I'm looking at generally have 20" tires

For the conversion,
* I need something technically simple (a kit, no welding). I am a fairly handy person, but am looking to make this relatively plug-and-play
* My assumption is that I'd remove the gas motor, pedals, and chain and this is just an e-moped, throttle on the handlebar for speed
* 'm thinking rear hub, and would only add a low power front hub if I found that I was having traction problems getting up hills (spinouts on wet leaves, etc)

I don't need a lot of mileage from a charge (5 miles would be overkill), nor do I need speed (15mph would be plenty) but I do need to go up and down hills, up to about 30 degrees, with a 200lb rider and gear (chainsaw and/or other tools). This is for use outdoors/offroad to get around for property maintenance.

I find low maintenance to be appealing (gearless hub?) although in my case I'm not sure if I should look at geared because of the intermittent torque that will be needed, I don't fully understand the pros/cons for my use case.

I'd welcome thoughts/suggestions (and links to example conversion kits, if that is allowed here)

Thank you!

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John and Cecil   1 kW

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Re: Hub motor kits specifically for mopeds?

Post by John and Cecil » Feb 13 2020 2:23pm

Hi, I am not sure what you are looking to do? Are you looking to modify a moped so it is street legal? Every state/country/area has different laws regarding legality of conversions/etc. I would think a moped could be converted to an e-moped. I would think the best (easiest) way would be to mount an electric motor in place of the gas motor and use a chain to drive the rear wheel. You would probably need to fabricate some sort of mount for the motor. You would also need a device to cut the battery voltage down to run your lights, etc. This way you would be able to utilize everything else on the moped like brakes, etc. Otherwise you would need to replace the rear wheel hub with a motorized one and have it laced into the wheel, and you might have to reinforce the dropouts or something as well and also come up with another braking solution. Batteries would not be much of an issue for only 5 miles, that would be a rather small battery but with cells with high amp output.

The issue I see is the moped is going to be very heavy for what it does and it is not very well suited for holding batteries, etc. (unless you are going to cut into the gas tank perhaps) so unless you are trying to build a high speed street legal moped it might be better to build a cargo bicycle, again depending on local laws. A cargo bicycle would be much lighter and you could add a small hub drive motor or a mid drive motor to replace the cranks (tsdz2, bafang bbs02/bbshd/lingbei, etc). A small 52v 5ah battery would be more than enough for 5 miles at 15-20mph (depending on how much of that is uphill). If you can find a bicycle that suits your needs and has a 68-73mm wide bottom bracket at the cranks then there is a good chance you could build an ebike with a mid drive. The cheapest of the mid drives plus a small battery would probably cost about $450, as would a decent hub kit like the mac 12t. The bbshd and small battery would be more like $850+ but that is capable of putting out twice the power of the other motors.

If the hill you need to climb is really 30 degrees (that is very, very, very steep - 6 ft rise only 10 ft away!) then you are going to need a powerful motor or a very low gear ratio. My guess is 1st gear would probably need to max out at under 3mph to be able to climb that hill with a sub 1000w motor. Even if using a wide ratio 8spd cassette means your top speed would max out at about 10mph in 8th gear. I would check that hill you need to climb before building anything. :) I am in Italy and even I have yet to come across a hill that steep. I climbed a goat trail up a mountain once which was probably 25 degrees in places and I had a hard time keeping the front wheel on the ground while trying to climb it. I made it up but I worked my @ss off!

Personally I like the idea of converting a moped or small motorcycle into an electric driven vehicle, but only if the right donor vehicle came around and only if I could get it to be street legal (registered, insured, etc). Until then I will be sticking to my ebike :)

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