Considering E-Bike project Hub motor or Drive Motor?

[addicted2climbing]

Hello All,

I have been on and off this site doing research for some time and I am finaly ready to take the plunge and build a bike. I am also currnetly working on electrifying a flexboard as well using R/C components, but these questions are aimed toward an E-Bike. Anyhow, I had been considering buying a Magic Pie for the front and electrifying a bike with a rear Alfine hub but after research on here I see there are better alternatives and also another option is build or buy a reduction unit instead of the hub motor option. I am beginning to lead towards the non hub motor and possibly buying a Nuvinci developers kit instead of a bike with an alfine hub. Before I head down this road I was curious as to the pros and cons of a hub motor bike in relation to a electric motor with a reduction then coupled to the rear wheel. Also I see there are direct friv ehub motors as well as the geared hub motors by BMC.

My goals are a bike that has a top speed of 30mph, but I imagine most of my riding will be more around 20mph. I would like a range of 15 miles on a charge to be able to use it as a commuter. That range is fine if I also need to pedal to conserve energy to get the 15 miles. Mostly flat ground. One issue is I am heavy at 225lbs.

I would like to convert a bike with 700C or 29'r MTB rims and road tires. For batteries I would like to use Li-pos or A123 batteries.

These are just rough specs to pose to those in the know to see if it makes sense to go one version or the other based on my aplication. I have access to a CNC shop here at work and I can design any brackets or drive components needed in Solidworks. So what are the pros and cons of each style? Also if there is a thread with this info already feel free to post a link. I am sure price is an issue as well, but if it were not which would make more sense...

Take care,

Marc

 

[dogman dan]

Well, hub motors with about 500-1000 watts make great commuter bikes that can go 20-30 mph easily, and the range you want is just a matter of carrying about 700 watthours. So 36v 20 ah, 48v 15 ah, 72v 10 ah, whatever.

But that would be no fun at all for a guy with the tools to fab stuff. So go for non hub so you can enjoy making cool stuff.

 

[AussieJester]

+1 ....if you have CAD skills and CNC access, you would be mad not to go non-hub setup, IMO....but then I am anti frock motor so its an easy call fOr me to make LOL

KiM

 

[addicted2climbing]

Hey All,

Thanks for the replies. I was leaning toward the seperate motor option, but also know I can make it work with a hub motor much easier. However I do like tinkering and design so I think I will persue the non hub option. I have a lot to learn and unsure whats the best way to have a seperate drivetrain for the motor and also still have the drivetrain for pedals. I need to do more research, but off hand does anyone know if I can mount 2 freewheels to a nuvinci hub? That would seem like a quick way of having sepearte drivetrains. If so can they be on opposite sides or do they need to be standard right hand driven?

Best regards,

Marc

 

[bdteakle]

I agree it would be more interesting (for everyone), and potentially more efficient to make something more original and custom working thru the gears. However I think your first idea was really good too.
I use a rear Alfine hub, and front Bafang hub motor on my main e-bike. It's so reliable, compact, and easy to do. I love the Alfine and its push-button gear changes, nothing compares. Rohloff's are impressive engineering, offer a big range which is great for non-electric bikes, but feel clunky to use in comparison. The Alfine has plenty of range for ebiking, because you don't need so many low gears. They're also cheap on Chainreactioncycles.com.
I don't get the speed you are looking for, as I only have a 200w motor but this is efficient and I only need to carry 10Ah for my long steep climbs.
If you want a bike to get on the road then your first idea will get you going. Perhaps you need 2 bikes (who here can get by with only one?).
Best wishes from Bruce.

 

[dogman dan]

Since all the CNC work will most likely take you till riding season is over, it could make a lot of sense to just buy a small front hub geared motor kit, some lipos, and get riding now. At 12s voltage, you wouldn't have 30 mph, but you'd have enough to cruise along in 48-12 gear real nice.

That's assuming you live north of the equator a bit. I'm guessing USA, because like me you think in idiotic mph.

The batteries will of course swap over to any bike you have later with ease. And you might end up making a mid drive out of the hub later too.

 

[addicted2climbing]

Since all the CNC work will most likely take you till riding season is over,

Hey Dogman,

I am in Los Angeles area so its riding season all year long.... LOL

I ended up ordering a Nuvinci Developers kit so lools like I am already heading the mid drive route... Right now I am working on the design to electrify my Flexboard (www.flexboardz.com) and I just ordered the outrunner motors and now working on the drive design and possible new suspension arm to accept the motors...

Marc