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  1. #1
    George Krpan
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    Who has the latest version of the Currie conversion kit?

    If you do, I have a some questions.
    My questions are about the kit for 26" wheel bikes.

    The chain that is turned by the motor to drive the rear wheel, is it ordinary bicycle chain?

    The gear on the motor, is it a freewheel AND is it like the ones used on BMX bikes?

    The gear on the motor, how many teeth?

    The gear on the wheel, how many teeth?

  2. #2
    Lyen lyen's Avatar
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    Hello GeoKrpan, below are the answers to your questions:
    1. The chain is not an ordinary bicycle chain. It is called #25 chain.
    2. It has a freewheel and it is not the ones used on BMX bikes.
    3. The gear on the motor is 11 teeth.
    4. The gear on the wheel is 54 teeth.

    Also, there is a gear box in between the motor and the wheel. Therefore, you cannot calculate the ratio like the bicycle gear ratio.

    Lastly, if your intenion is try to built or copy the Currie's left gear one, than you cannot because you need a unique gearbox. Technically you can, but you need to have 10 teeth for the motor and 120 or more teeth for the wheel in addition to the freewheel.

  3. #3
    George Krpan
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    Thanks for the answers.
    Is this the kit that you have?
    http://www.nycewheels.com/currie-ele...ve-system.html

    I was toying with the idea of driving a crank on the left side instead of driving the wheel.
    If it used a regular chain and freewheel it would probably be a cinch.
    I guess there might be a way to adapt the wheel gear to fit on a crank.

  4. #4
    Senior Member
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    Geo
    .
    I considered driving a 'stokers crank' on the left end of the bottom bracket so that the motor would use all of the bicycles gears. A lot is of it is doable. The motor sprocket could be replaced with a freewheel mounted on a BB cup. BMX freewheels have an ID like a BB. It would be a conventional "right hand"freewheel. But the smallest freewheel you can get is 13 teeth. That would mean that the stokers chainwheel would have to have about 65 teeth to get the motor to turn the crank at about a cadence of 60ish (like a person) so that the bikes gears could be used to both speed up or add power (about equally) from straight thru. I may not have all the numbers just right my thoughts on this were a year ago.
    .
    Also the freewheel protects the motor from being forced forward (gear boxes don't like that) but nothing protects the rider from being batted by a powered pedal.
    .
    for what it is worth, Don

  5. #5
    George Krpan
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    Don, thanks for your sincere comment.

    I went to a Currie dealer today and saw a Currie bike with the LATEST kit installed on it.
    The drive chain from the motor to the wheel uses ORDINARY BICYCLE CHAIN.
    It does NOT use #25 chain.

    The freewheel has been moved to the wheel. There is a gear on the motor but it is not a freewheel.

    That is unfortunate for my plans because now I will have to figure out how to mount a freewheel on the motor shaft.

    If anybody has any ideas about how to do this, please post a comment.

  6. #6
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    Geo
    .
    I guess I wasn't very clear. The freewheel has always been on the wheel.
    .
    To put the freewheel on the motor, the idea I suggested of a 13 tooth BMX right hand freewheel threaded onto (with loctite) a Bottom Bracket cup slipped over the motor shaft (pinned if you have the skill/drill) and held on by the nut is a proven thing. I've done it.
    .
    Let me know if you solve the gear ratio problem. The motor shaft rpm (at the gear box output) is posted lots of places. You can calculate the ratio you need based on how fast you want the crank or whatever to turn.
    .
    For the idea I tried, the freewheel on the wheel had to be removed to give clearance for the chain headed to the crank. It has a lefthanded thread.
    .
    Don

  7. #7
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    I own this style of ebike conversion. Although, I had always wanted a hub motor, I have to admit that this style is quite affordable and I really enjoyed it. I am committed to making good use of it, before I retire it for something nicer.

  8. #8
    George Krpan
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    Don, thank you, thank you, thank you.

    Will you, if possible, tell me exactly what BB to get?

    I guess, I would start with the biggest chainring that would fit on the bike.

    There is something called a freewheel cassette driver.
    Example: http://www.customriders.com/prodshow...ent=1001&sid=3

    Gears are available for them as small as 9 teeth.
    But, of course, I'd have to figure out how to install one of these on the motor shaft.

    Do you know the diameter of the motor shaft. 10mm?

  9. #9
    Lyen lyen's Avatar
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    My "kit" is actually a better design because it uses a more powerful brushless motor instead of the brushed motor. The gearbox design is also more robust. I have optimized my motor set to go up to 22-23 MPH instead of 18MPH from the kit you mentioned below using the same battery. But basically it serves the same purpose.

    Quote Originally Posted by GeoKrpan View Post
    Thanks for the answers.
    Is this the kit that you have?
    http://www.nycewheels.com/currie-ele...ve-system.html

    I was toying with the idea of driving a crank on the left side instead of driving the wheel.
    If it used a regular chain and freewheel it would probably be a cinch.
    I guess there might be a way to adapt the wheel gear to fit on a crank.

  10. #10
    Senior Member
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    George
    .
    It's just the BB cup you need. That is the cup from any loose bearing BB. The OD is 1 and 3/8", the same as the threaded portion the hub that accepts the freewheel on any rear wheel.
    .
    The center hole where normally the spindle would come out to accept a pedal accepts the motor shaft just fine.
    .
    I'm not sure how you would make use of a cassette driver. This approach is for a freewheel not a cassette. The gear has to be, on the shaft, close to the motor output both to keep the chainline correct to the stokers chainwheel and to prevent side loading the motor shaft. You need a freewheel there. 13T is the smallest I found. If you can find a way to use a cassette rather than a freewheel, please share the news.
    .
    As far as shaft diameter, RPM etc., go to http://www.evdeals.com/ they sell all the stuff and have a good page showing specs. They sell the transmission Lyen is talking about. It all comes to many times more expensive than Currie.

    Quote Originally Posted by GeoKrpan View Post
    Don,

    Will you, if possible, tell me exactly what BB to get?

    I guess, I would start with the biggest chainring that would fit on the bike.

    There is something called a freewheel cassette driver.
    Example: http://www.customriders.com/prodshow...ent=1001&sid=3

    Gears are available for them as small as 9 teeth.
    But, of course, I'd have to figure out how to install one of these on the motor shaft.

    Do you know the diameter of the motor shaft. 10mm?

  11. #11
    Senior Member
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    George
    .
    If you buy a kit, I'd advise that you not make any irreversible mods. You may want to go back to the original design if you find you can't spin your legs as fast as the motor spins the pedals. From my experience, with the chainwheels I could find neither I nor Lance Armstrong could spin that fast.
    .
    I might not have made it clear the freewheel (or freehub, if you could fit in) stops you from driving the motor against its will and ruining the gear box. Nothing prevents the motor from driving the pedals against your will or against your ankles.
    .

    Don
    Last edited by donob08; 08-04-09 at 12:19 PM.

  12. #12
    George Krpan
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    Ok, the cup from a loose bearing BB, haven't used one in years.
    Profile Racing makes something called a mini cassette hub. The choice of cogs for this hub is 9 to 18 teeth.
    What I'm thinking is to install the cassette body from this hub on the motor shaft, somehow.
    I looked at EvDeals.com a little last night. I'll spend some more time looking at it.
    More to come.
    Thanks for your help, Don.

  13. #13
    George Krpan
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    Ya' let go of the throttle and/or shift up to a higher gear. Put more load on the motor to slow it down.
    That is the beauty of driving the crank as opposed to driving the wheel.
    More to come. You've been great. Thanks.

  14. #14
    George Krpan
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    Here is a link to a picture of a cassette driver with a 9 tooth gear.
    http://www.danscomp.com/461082.php?cat=PARTS
    It is available in left or right hand drive.
    If you wanted to get the gear as close to the motor as possible you could get a left hand drive and mount it backwards.

  15. #15
    George Krpan
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    Don, how big a chainring would you need with a 9 tooth cog to get 60 rpm at the crank?

  16. #16
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    Quote Originally Posted by GeoKrpan View Post
    Don, how big a chainring would you need with a 9 tooth cog to get 60 rpm at the crank?
    http://www.sheldonbrown.com/gears/

  17. #17
    Senior Member
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    It looks like normally an Odyssy Hazard Hub $80- $130 would accept a
    Hazard Cassette Driver Price: $35.00
    .
    The hub is a special product popular with BMX racers. It would normally be laced into a wheel. It has a special axel and bearings. It looks like the axel is one of those sorta splined one way clutch thingees, maybe.
    But you want to put this on the motor. I guess you would have to make the motor shaft look like a Hazard axel.
    .
    http://www.danscomp.com/428023.php
    .
    Dan's Competition
    1 Competition Way
    Mt. Vernon, IN 47620
    1-812-838-2000
    Customer Service

    International Customers
    Toll Free USA: 1-888-888-3267, Options 3, 5
    Fax: 1-812-838-2693
    Mail: 1 Competition Way
    Mt. Vernon, IN 47620
    Email: customerservice@danscomp.com
    .
    Danís might be able to clue you in by phone.
    .
    About the chainwheel needed:
    Unite Motor which makes the motor
    ∷SHENZHEN UNITE INDUSTRIES CO.,LTD
    http://en.unitemotor.com/ProductView_41.html
    They say rpm motor = 3000, gear reduction = 7.18:1 so output shaft rpm = 418 rpm
    418/60 = 6.96 thatís the gear reduction needed.
    Therefor to get 60 rpm at BB need 63 Teeth on the chainwheel, with 9 teeth . Pretty BIG.
    For my 13 T freewheel it would be 90 Teeth at the chainwheel.

    On the load the motor up and slow it down idea, could work, and yes I went to some trouble pursuing this because I too wanted the gears in the loop, but don't underestimate the torque a DC motor can put out if you try to slow it down. That's when its torque peaks. 'Aint no hill eZip won't climb' if you've got enough battery.
    Last edited by donob08; 08-05-09 at 04:47 AM.

  18. #18
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    George
    .
    A thought that I have communicated badly, or not at all, is that the main reason I wanted to use the 21 different gear combinations on my eZip was to increase efficiency. I don't really need more speed or more torque. I wanted to reduce the current draw from the battery by using the gears to reduce the torque and battery current needed in some conditions. Your ' gear up' = punish the motor into slowness kinda defeats that.
    .
    I'm trying to tread carefully and not discourage your creativeness, but battery life per charge is one of the factors in the equation.

    be well, think well
    Don

  19. #19
    George Krpan
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    Thanks once again, Don.
    No one has actually built the bike that I propose to build. So, no one really knows how it would work out in the real world.
    So, for the time being, I'm going to plan on going with the BB cup, 13 tooth freewheel, and biggest chainring that will fit on the bike.
    If it's a bust I'll have to think of something else but I might as well try what's easiest for starters.
    On comment about chain line. The length of the chain from behind the wheel to the crank will mitigate the issue significantly.
    More to come.
    PS I'm thinking of installing the Currie kit on a Kona Smoke 29.

  20. #20
    Senior Member nwmtnbkr's Avatar
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    You're thinking of the Currie Pro Drive Conversion Kit, which may not be available anymore. I believe it has been replaced by the Electric Drive Motorkit, which is what I recently installed on my mountain bike.



    If you want the old design of the Pro Drive Conversion Kit, you should check the stokemoney kit for the xtracycle.

  21. #21
    George Krpan
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    I know about the Stokemonkey. It's what inspired me to have a "through the gears" electric bicycle.
    But, I don't want a long bicycle and it's $1700. I'm not saying it's not worth it.
    The current Currie kit was recently on sale from Currie for $299.

    Will you do me a favor? Count the teeth on the gear motor and on the freewheel on the left side of the rear wheel.

  22. #22
    Senior Member nwmtnbkr's Avatar
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    Quote Originally Posted by GeoKrpan View Post
    I know about the Stokemonkey. It's what inspired me to have a "through the gears" electric bicycle.
    But, I don't want a long bicycle and it's $1700. I'm not saying it's not worth it.
    The current Currie kit was recently on sale from Currie for $299.

    Will you do me a favor? Count the teeth on the gear motor and on the freewheel on the left side of the rear wheel.
    The OEM freewheel has 20T. I think you might want to read this thread on ecoforumz regarding one member's efforts at increasing the speed of his eZip by decreasing the size of the freewheel (he couldn't find a comparable motor sprocket so was limited to changing the size of the freewheel for his project). It's very interesting, he's easily getting 20MPH using the standard OEM SLA battery pack. Here's a link to the thread. http://www.ecoforumz.com/electric-bi...-oem-pack.html

    FYI, here's a picture in his thread of the OEM freewheel (larger) next to the new, smaller freewheel he's using to get increased speeds.


  23. #23
    George Krpan
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    I'm thinking, by powering the cranks instead of the rear wheel, and thereby utilizing the bicycles drivetrain that 30 mph will be easily attainable.

  24. #24
    Senior Member nwmtnbkr's Avatar
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    If you haven't already, you might check out the design of the DreamE bikes. Their power assist motor connects to the bike's crank. (There are two motor options 360W and 500W.) Here are some photos from a retailer's web page.






  25. #25
    George Krpan
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    Looks like the Cyclone kit. Do you see how they used an ordinary bicycle freewheel on the motor?

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