Mountain bike electric conversion

I am thinking of transferring the electrics from my electric bike to my new mountain bike -- a very interesting project, I reckon!

The electric bike is an el-cheapo from Kmart, AU$399, that I purchased about a year ago. In Australia, a power-assisted bicycle can be a maximum of 200 watts. Same in the UK. The European Union has settled on 250 watts.

The motor on my bike has a "200 watt" sticker on it, but I think it's the same one as the top pics at this site:
(the motor with the ribbing around the circumference)
That does 250 watts. I have read that the Chinese manufacturer just puts the appropriate sticker on it as per the target Government legislation requirements.

Anyway, what has intrigued me about that above url is the option of mounting the motor at the other end, that is, onto one of the sprockets at the human-driven-pedals-end. On my electric bike, the motor is mounted beside the rear wheel, with a small chain driving the real wheel, on the opposite side to the derailleur gears. Moving the motor to the front is an interesting alternative, but note the author's negative comments near the bottom of the page.

Posted on 8 Aug 2008, 10:05


Posted on 8 Aug 2008, 11:56 by ANOSage
You need a hub motor for efficiency. Efficiency is a essential because there are severe issues with battery choice, range and deployment. This is a subject area I've investigated and taught for three decades. We even devised a radically new design of super-ebike but had no take-up from industry and haven't the workshop facilities to implement. Probably a topic for separate correspondence.

Posted on 8 Aug 2008, 13:47 by John_Doe

check out bionx (it's a hub motor system like Sage is talking about)

it's probably the most state of the art system out there. I've been dreaming about having one for a year now. Induction to pump power back into the battery cell sounds pretty cool.

Also, I just ordered one of these for charging stuff as I go:

I've got a cigarette lighter plug with a usb slot to power up a couple of my mobile devices via a tiny USB hub while I ride (a generator like this would be silly if you have a bionx system, yet welcome on a motorless bike).

Posted on 8 Aug 2008, 14:59 by Gill Baits
looks the part
I also have been planning on getting a electric bicycle after a lot of looking around have decided to purchase a bike from though they do seem to be expensive they do look quite robust, now all I have to do is save up the money

Posted on 8 Aug 2008, 15:43 by ANOSage
Avoid the zbike! Although Canadian, the Bionx seems to suffer southern-neighbour-hype syndrome. I think they mean 8Ah - that should be good for ~8miles range, perhaps. So far, I cannot get NiMH technology to work satisfactorily on my ebike - it cannot supply sufficient peaking power from spirally wound cells. Specialist Li-ion cells can do this, but not at that price and their lifetime in such an application is unproven. TMF lead-acid cells perform spectacularly in dragster bike racing, easily beating reciprocating engines on nitrous - you can get at least half-a-dozen runs out of them! As the deposed CEO of GM infamously said of the brilliantly engineered Impulse "We chose the wrong battery". There was/is no choice and therein lies the problem.
I'd be happy to correspond with folks having a sustained technical interest in ebikes. Despite the economic miracle and the smog, there is still a multi-million market opportunity for ebikes in SE Asia, especially to replace tuk-tuk's and those all-purpose family shifting scooters beloved of our Indian friends; just off for a masala dosai breakfast....

Posted on 8 Aug 2008, 17:11 by BarryK
The Panther Zbike looks awesome:
It's exactly what I want -- an electrified mountain bike, and the AU$1395 is quite attractive. Today I was looking around online, and that price seems quite low. Sage has reservations about the battery, and that would be a significant proportion of the cost. My el-cheapo has two 12v lead-acid batteries (in series) -- the main disadvantage being the limited number of recharge cycles compared with the later technologies (as I understand the situation).

I used to have some knowledge about lead-acids, back in my lecturer days. I guess, even if it's recharge cycles are very limited, it is relatively cheap so can be replaced every year or whatever. I presume they do recycle batteries these days -- hope so.

Posted on 8 Aug 2008, 17:21 by BarryK
Panther Zbike
Ah, looking at the web page a bit more closely, maybe for AU$1390 you are only getting lead-acid batteries, as they state Lithium-ion battery upgrade is $400. Still a good price though.

My el-cheapo has two 12AH 12v sealed lead-acid batteries -- it doesn't say so on the label, but I presume they are designed for deep discharge. What would they cost? -- 50 bucks each?

Posted on 9 Aug 2008, 2:55 by purple_ghost
What about.
I have seen a bicycle with a gasoline motor about the size of a lawn edger driving the chain.

Posted on 9 Aug 2008, 4:30 by lwill
Controller/motor supplier
I'm not real familiar with bike convertion, but if you want to go serious DIY I ran across this company while looking for a fork lift controller.
Some even do regenerative braking to help recharging.
Might be a bit pricy, but if you got serious mountains, you need a serious mountain bike...

Posted on 9 Aug 2008, 13:44 by John_Doe
> Although Canadian, the Bionx seems to suffer southern-neighbour-hype syndrome.

Sorry about the "hype syndrome" and btw I thought it was German for some reason. I could have sworn that when I was first looking at it (~1 year ago) that it was built in Germany. Not sure what happened. Seems from review of the current web pages that it is made in Canada now.

carry on...