About to build Mr and Mrs e-bikes; advice needed (and thanks)

MikeFairbanks

100 kW
Joined
Mar 9, 2010
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1,385
Location
Atlanta, Georgia, USA
I've built a few e-bikes and understand how they work, how to install, etc., but it's been about three to four years since I built any.

My wife and I have a couple nice Trek Cruisers and we want to install a couple front-hub motor kits.

We want them relatively light, pedal assist, a bit stealth. Maybe geared hub? I've always used DD hub motors, but they are heavy and obvious.

These bikes will be for cruising through various downtowns like Atlanta, Nashville, etc. Nice and easy pedaling with some help on the hills. We don't need fast. I'm probably thinking 36volt, 9-12ah.

Are there good kits with or without batteries that you guys can recommend? And if separate, which battery suppliers are currently the go-to for everyone?

Thanks.
 
What kind of PAS are you looking for?

Some use on/off, meaning that if you are pedalling at all, it just gives you whatever it's set for, either in power or speed (depending on the design). Some don't have settings to change this, so it's all or nothing.

SOme base on cadence, so faster you pedal the more it gives (speed or power, agian depending on design).

Some use torque sensing, so the harder you pedal (different from the above) the more it gives.


Then there is the Cycle Analyst v3 from Grin Tech, that lets you set it up any of those ways, or even have multiple presets with it different on each one; this is just a computer that goes between throttle / pedal sensor and any controller, and translates the inputs based on your settings to get you the controller behavior you want. Works better with dumb controllers so you aren't fighting with the controller settings and whatnot, as well as setting up the CA.



Fast is relative, so you need to define the speed you want out of it. For some, 30MPH is not fast, for others, 15MPH is pushing the limits.

You should also define the "hills", as there is a great deal of difference in power requirements from small short rises and falls to larger hills. (And even definition of hill can be different--in PHoenix we have mountains that ohter places call hills).

And the length of the climb and the speed at which you need to do it are important as well; if it's a long slow climb the motor may overheat if ti's too small.


FWIW, front hubs will be the least stealthy option I can imagine, in the low-power stuff.


Regarding battery, I don't recommend you set a limit on that (36v 9-12Ah) until you know what capability it has to ahve to drive the system under worst-case conditions, or you may end up stressing the battery whenever that happens. Pick the system first, then determine it's worst-case needs, then pick a batteyr that can easily supply that, that also meets your stealth and other requirements.
 
We'll never have a need to exceed 20mph. I've built many 48 volt systems that hit about 29mph, but that isn't necessary.

I was wondering what suppliers are currently recommended these days for both kits and motors. I'll sort through their options and pick something that will work for both my wife and myself.

There's a lot on Ebay these days.

I used to get kits from EbikeKit.com, and they are excellent kits, but they're a bit more in price than what can be had from other websites.

Thanks
 
If you're looking for cheap, there's been plenty of $200-$300 "kits" on ebay, but I have no experience with them so can't vouch for reliability (or even if they are plug-and-play, rather than you having to figure out all the wiring on your own, which is still way too common with "kits").

For myself, if I had money for it, I'd just buy from Grin Tech to support their work and development of nifty new things, and I'd buy the advanced stuff like the Phaserunner controller and the Cycle Satiator charger, along with a Cycle Analyst to control / monitor everything thru, even if I was building somethign that doesnt' need high power, rather because these things are generally higher reliabilty than other stuff I've dealt with. But they're definitely not cheap, and they sometimes (maybe often) have the same item someone else does but significantly different in price. However--they also have customer service, which not all places do (even if it isn't perfect). You might never need the CS, but it's good to know it's there if you did. ;)

There are other suppliers I've seen builds around, here on the forum, but dont' know how good or bad any of them are from my own experiences (not counting personal interactions with owners or employees, which isn't what you're after).

If you want super stealthy, the "cute" motors are very small, and there's been some threads about some newer even smaller ones with dual reduction--I think one of the threads was started by Neptronix so you could look thru his posts for that. I don't know what their cost range is.

Keep in mind that the smaller it is, the less continuous power it can handle, so you need to at least guesstmate how much power you''ll need before you pick a motor. You don't want to get stuck with systems that overheat and fail just from your normal usage.
 
I can't recommend a kit, but if you want stealth, consider a small geared hub on the rear. With a rear disc brake and the gear cluster, those motors tend to visually disappear.

Also, if you have experience building ebikes why bother with a kit? Just buy the parts. If you buy from overseas you can probably save a little bit of money if you have everything shipped at once, dropping your shipping costs per kit.
 
I bought and installed a Pasion DD hub kit from Aliexpress. It was very easy to install and all went together without issue. The do a geared kit too that uses a Bafang motor. They use KT controllers with the LCD3 interface. The motors come pre-laced into a rim which saves a bit of time and hassle.

I built my own battery but I have heard good things about EM3EV for the highest quality packs (they also sell kits, but I don't think they sell geared hubs), or Unit Pack Power for a slightly cheaper option.
 
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