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  1. #1
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    Post e-bike information?

    Hey guys, I'm very new to the world of e-bikes. I built a gas powered bike last year with my roommate (Which was a PITA) and now I want my own powered bike but without the mess of a gas motor. I am looking to spend less than $400 for a kit because I can't afford much on a college student budget. I have a very nice bike already and I think I want an electric front wheel to power it. From what I understand, a rear wheel would be better for traction and whatnot, but my bike goes through quite a bit, and I've bent my share of rear rims. The front wheel just seems to take less impact and therefore less of a chance to bend/break. Anyway, I could use some information. For example, Is there a difference in the motor of the 24v, 36v, and 48v hubs? They all look identical. Obviously there would be speed differences between the different voltages, but are they substantial? I only need the bike to get me around a university campus so I don't need to fly, but I still enjoy a bit of speed. Last question, what is the difference between the wattage of the hub motors? (i.e. 36v 250w vs 36v 500w) Does more watts = more electricity used = faster/more torque?
    Thanks in advance, guys and girls!

  2. #2
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    the more volts (i.e. 48v vs 24v) will be a motor that can handle more watts.

    from the sound of your post, i don't think you'll be happy with a 24v motor. i think you should get a 48v 500w motor.

    since your budget is $400, that's pretty low for most systems. i would either go with one of the ebay kits or one of the e-bikekit kits.


    but the problem is batteries. it's hard to go within that budget if you want to include batteries. i don't recommend SLA...just too heavy. i would get a 10ah 48v ping battery (still over your budget) or if you're willing to be more of a DIY guy, get some lipo and do a ton of reading (might be able to squeeze in 2 6s 5000mah batteries + cheap balance charge) into your budget.
    2012 Cervelo R3 w/ SRAM Rival
    2012 Brompton M6R
    2012 Dahon Speed D7 - 9c 2806 rear hub motor + 12s 5ah lipo = 25mph
    2009 Trek 6500
    TidalForce S-750 electric bike - 9c 2807 rear hub motor + 14s 15ah lipo = 35mph

  3. #3
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    Hub motors are broken up into 2 types...

    1.) Small Geared
    2.) Larger Direct Drive

    Small geared are usually in the 250-350w range.. They are lighter, more torquey, but have less top end.
    Direct drive are usually in the 500-1000w range.. They are heavier (not by much) and are capable of much faster speeds...

    To speak to the "wattage" of a motor is a misnomer...
    The wattage is USALLY set by the controller that runs the motor..
    (i.e. This is no difference between a 500w and a 1000w "motor", it's the controller that provides more power (amps) and is the controlling factor..)

    Most geared motors will handle up to 500w, after that, you really need a direct drive..
    DD motors can usually handle 1200w continuous, without issue..
    The more watts you start pushing into the motors, the more that the energy put in is transfered to heat.

    As a general rule...
    24v will get you 15mph top speed (usually 250-350w)
    36v will get you 20mph (350-750w)
    48v will get you 25mph (750w and up)

    The equation is V olts times A mps = W atts or VxA=W

    As you will notice, all of those figures equate to 10-15 amps on average...
    (24v X 10a = 240w, 24v X 15a = 360w)
    (36x X 10a = 360w, 36v X 15a = 540w)
    Etc, etc...

    So a 36v 15a controller will provide up to 540w (36v X 15a)
    a.k.a. A 36v 500w motor
    If the controller was a 30a one, then I would be (36v X 30a) = 960w
    Or a 36v 1000w motor.

    Hope that all makes sense.

  4. #4
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    Thank you guys! I have a much clearer understanding now. I think I want to get either a 36v or 48v one, still not quite sure. Yes SLA batteries are heavy, but they're cheap.

    I would get something like this
    http://www.ebay.com/itm/36V-700W-26-...ht_7225wt_1396
    or this
    http://www.ebay.com/itm/48V-500W-26-...ht_7392wt_1396
    with 3 or 4 of these
    http://www.batterymart.com/p-12v-18a...battery-1.html

    the total I would have to pay (the 48v kit) would be $390 after shipping.

  5. #5
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    Hope you like waiting 2 months for your motor kit.

  6. #6
    Senior Member
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    I ride on 36V and don't fit general rule , because I reach 30mph regularly consuming just 1100W absolutely maximum with motor barely warm to the touch.
    Which is excellent result.
    You don't want to waste your battery Wattshours on heating of motor; you want to draw as little power as possible for given speed,
    it is called efficiency.

    It is quality,efficiency of all ebike and mostly of motor/controller even bearings which decide about watts drawn for given speed.
    Last edited by powell; 02-01-12 at 09:11 PM.

  7. #7
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    I said "Something like this" as in not necessarily one of those. And Powell how many miles / hours do you get out of your batteries, and what is the capacity of your batteries? I'm also interested in knowing which kit you have.

  8. #8
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    There is thread about E+ called E+ review quite active with many pages.
    I bought E+ 1000W kit. What is unique about E+ system is that it is USA designed and made in US motor/controller.
    It has 9 power levels which really work, in power level 2 I rode 55km on sunny warm day.
    In power level 8 I can ride around 20-25km with 150lb rider, on flat , no wind, warm day.
    E+ uses high quality Golden Peak 9Ah cells so pack is 36V 9Ah.
    E+ is one of the best out there and can be powered on any 36V battery

  9. #9
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    Wow. That kit looks phenomenal. The battery in the rear hub? Genius. Looks like a quality kit, but for $1100 I can go to the bike shop across the street from where I live (Giant brand bike shop named cadence120) and buy a fully constructed Giant e-bike... (http://cadence120.com/product-list/b...electric-1038/) But that's way out of my price range, haha.

  10. #10
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    You can get a motor kit and batteries that will get you a 20mph 40mile range for $750..
    How's that for your price range?
    Drop that down to $650 and you get 30 miles.
    Drop that down to $600 and you get 20 miles.

    Pm me for more info.

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