Hub motors? no chain

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2/24/2018 3:49 PM

Saw one of these laced to a Warp 9 rim. If one of these hubs can hold up to mx it would be great for a blown up 4 stroke to electric conversion.
Back end would be heavier, but could the batteries be positioned forward enough to compensate?


2/24/2018 3:55 PM

Basically I am thinking about copying this build to an extent into maybe a first generation RMZ450 chassis. I am waiting for an email reply from Enertrac where I asked if the hub would hold up to motocross.


3/2/2018 10:29 AM

Unsprung weight is the worst kind of weight.


3/2/2018 5:52 PM
Edited Date/Time: 5/6/2018 7:46 PM

I was thinking about that unsprung weight. I might wind up being a hack job test dummy on the design and see how different/bad it really is. There are a few mx bikes on Enertrac's website with the hub motor. I guess it might atleast be ok for trail riding in stealth mode. I really think it's only a matter of time before conversion kits are available.
I may cobble up a bike to ride and maybe get a legitimate e bike once the boys get big enough to go to the track.
It wouldn't add up just yet for me to get an Alta.
Sure as hell want an MXR tho.


7/11/2018 1:00 PM

Months late, but I think this specific hub motor is perfect for building a first e-bike, excluding the cost factor. Very little fab, you'd be running in no time and It'd be fine for light trails. The article says he used a Sevcon Gen 4 motor controller, which you could use for a 'traditional' build later on. Likely whatever battery you chose could be used later on as well.

The battery is always the toughest to sort out. Tesla and Alta and anything decent are using 18650 cells, but there are tons of variants. You'd need three in series and ten in parallel of 3200mah cells to build one of the eight packs from that exodyne, so that's like 240 cells total. The Panasonic NCR18650GA are really good quality cells, but they're about $5ea. You can find better deals on other brands, maybe $2ea or even less. Maybe score a used Tesla battery on eBay and reconfigure it. They're about $1500 for a 444 cell pack on eBay.

The Alta battery is a really impressive 5.8kwh pack. I don't know what the voltage is, but if it were 96v, that'd be a 60ah battery, nearly twice the capacity of the exodyne and only weighs 68lbs. If they used 3000mah cells, they'd need to stuff 480 in there. Pretty crazy, but the weight numbers work out, so I guess that's what they're doing.

Anyway, cost becomes a big problem. You're at $1300 for the hub motor/wheel, $700 for the controller, maybe $1000 for the battery, so you're at $3k for just the core components excluding the donor bike and a hundred bits and pieces. Add another $1k for a blown bike, maybe another $1k for all the other stuff and you're looking at $5k for what's honestly a pretty lame trail bike. You could pick up a fuel injected 2015+ 450 for $5k and it'd be much lighter, faster, with greater range. That's a tough pill to swallow, depending on how you value your money.

So if the dollar-to-performance part is important, then you have to ditch the hub motor and go for the mid-drive so that it'd at least be robust enough to ride it like a proper dirt bike, because I bet you'd eventually cook, or blow that hub motor to pieces riding moto, or rocky, technical stuff. Maybe if you already had the bike, scored a good deal on the battery and could get a plate for it so it'd have more use, then maybe the hub setup isn't so bad. Plus you could probably get a grand for it on resale.


8/6/2018 9:23 PM

I owned a Stealth Electric bike (before buying an Alta). The rear-handing unsprung motor was okay for slow street riding, but it would be horrible for any off-road racing or motocross.

First -- I pinch flatted a few inner tubes and dinged up the rear rim until it cracked.

Second -- Jumping with the rear hub motor is extremely unpredictable. There is no telling whether it would kick you or not. The bike never felt balanced either.

Third -- A heavy rear end is horrible for brake and power slides. It is hard to break loose, but if you do break it loose, then it is hard to stop the rotational momentum. The bike just wants to keep spinning. I was never comfortable doing any performance riding on it.


8/12/2018 6:46 AM

Interesting. Yeah I gave up and bought an Alta MXR.


8/12/2018 9:55 AM

A small hub motor on an Alta would be awesome. 2WD!