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  1. #1
    Senior Member DrkAngel's Avatar
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    Lightbulb 20mph or Bust(ed) - USA "Legal" eBike Speed

    Quote Originally Posted by DrkAngel
    - from Speed vs Range
    Anyway
    10mph = 46 miles range
    15mph = 30 miles range
    20mph = 20 miles range
    25mph = 13 miles range
    30mph = 8 miles range
    The 20mph USA "legal" eBike speed begins to look more "reasonable" than it did originally?


    I have multiple "compliant" eBikes:

    Comfort Cruiser
    2009 eZip Trailz LS (Low Step)
    No pretenses, 20mph limit on a big tired, low slung big suspension seat, full upright position.
    Typically I "cruise" at 15mph and "meander" even slower.
    Designed for motor only, but I do apply some assist getting up to speed and on hills ...
    Dumped the 24V 10Ah SLA batteries and packed 25.9V 25.92Ah LiPo into the oem eZip battery case.
    The battery upgrade, combined with the 16T upgrade provides a reasonable ~20mph.




    The Commuter
    2008 eZip Trailz
    Designed to commute at a sustained 20mph.
    29.6V 31.2Ah homemade Li-ion battery pack.
    16T upgraded drive gear.
    Smaller, higher pressure, Kevlar belted, low RR tires.
    Proper pedaling position seat.
    Designed for continuous pedal assist, motor only 20mph+, reasonable pedal assist provides extended range or a sustainable 25mph.
    Safety gear includes reflective tires, strobe headlight tail and turn signals, (mirror is mounted on helmet).

    Snow Beast
    2008 eZip Mountain Trailz
    Winter only, designed to mush through slush, snow and ice.
    OEM 20T gearing but upgraded from 24V SLA to 33.3V 31.2Ah Li-ion for a ~20mph capability with a substantial torque increase. (1st upgrade 37V 20.8Ah Li-ion battery replaced for better durability and 20mph legality)
    Homemade studded tires ... front tire quick swaps between mountain tread and sheet metal screwed mountain tire, dependent on road conditions. Rear tire is a used carbide studded tire, drive wheel wears steel studs too quickly. Home made studded provides better traction than the carbide.
    I do assist for extra umph, when needed,
    When really icy-nasty ... I lower seat and ski my feet.



    Might have gone overboard with this one ...


    Then I went way too far ...


    So 20mph is OK by me ... though I might push the limits.
    Last edited by DrkAngel; 12-28-14 at 08:34 AM.
    "Best of all! ... I get to play. ... http://www.bikeforums.net/attachment...&thumb=1&stc=1
    Sorry! ... I'm addicted to improving enhancing.
    With side orders of inspiring enlightening!"

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  2. #2
    Senior Member DrkAngel's Avatar
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    So 20mph is OK by me ... though I might push the limits.

    By tuning voltage, amperage and gearing, I can limit motor only speed to the "legal" 20mph, but provide substantial motor assist above 20 mph.
    Even modest pedal assist might provide 25mph+ speed and some assist is available right through 30 mph!

    To really suck all the potential out of the 20mph 750w motor limits, (USA legal Bicycle definition - limitations), you need a programmable controller with speed sensor.

    I do have a Haro 700C 24speed I intend on gearing for 22.2V 43.2Ah battery that provides 20mph capability ... might be a switch that "TURBOs" to 44.4V 21.6Ah (providing 30mph+ capability), 48-11T sprockets allow 30mph+ pedal assist at 90rpm. I built a 700C eZip motor compatible wheel. (Long Yih 8spd 32-11T & ACS 16T)



    Simpler-easier is a 44.4V battery with an adjustable potentiometer in the HALL circuit of the throttle. This would allow trimming speed to precisely 20mph ... with a hidden TURBO button-switch that allows full power.

    Legality is fine ... when taken in moderation.
    Last edited by DrkAngel; 12-28-14 at 09:42 AM.
    "Best of all! ... I get to play. ... http://www.bikeforums.net/attachment...&thumb=1&stc=1
    Sorry! ... I'm addicted to improving enhancing.
    With side orders of inspiring enlightening!"

    Acronyms

  3. #3
    Senior Member DrkAngel's Avatar
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    Lightbulb Power Required For Various Speeds

    A differing summation of watts required for a mountain bike to maintain various speeds.

    *5mph = 22w
    10mph = 68w
    15mph = 163w
    20mph = 333w
    25mph = 601w
    30mph = 993w
    35mph = 1532w
    40mph = 2247w
    45mph = 3147w
    50mph = 4280w
    * from ebike.ca simulator

    30mph requires almost precisely 300% the energy as 20mph.
    Of course, it does not require 3x the energy per mile.
    163w/15mph = 10.86wh/mile
    333w/20mph = 16.66wh/mile
    993w/30mph = 33.1wh/mile
    Still 30mph require 2x the energy per mile, or ...
    Same ~36V 10Ah battery ...
    15mph = 30+ mile range or - 92.08 miles per kWh = 6 hour cruise time
    20mph = 20 mile range or - 60.02 miles per kWh = 3 hour cruise time
    30mph = 10 mile range or - 30.21 miles per kWh = 1 hour cruise time
    "Best of all! ... I get to play. ... http://www.bikeforums.net/attachment...&thumb=1&stc=1
    Sorry! ... I'm addicted to improving enhancing.
    With side orders of inspiring enlightening!"

    Acronyms

  4. #4
    Senior Member DrkAngel's Avatar
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    30mph or run down ...

    I live in a small city with every street within several miles limited to 30mph.
    Most anywhere there are multiple routes available ... most everywhere ...
    In particular, there is one ~5 block stretch of 4 lane, no shoulder, that I must traverse on a daily basis.
    Usually I hop on from a side street at their red light and hump it up to 25mph+ to stay ahead of them.
    Sadly, motor assist declines from about 12mph and is nothing at 25mph.

    Ideally, I could fine tune a bike for motor only 20mph but supplies substantial pedal assist to 30mph.

    With the proper voltage and amperage "fine tuning" this is possible.
    Using the ebike.ca simulator I "built" this example ...



    Overvolting, while reducing amps, provides less assist below 20mph but gives substantial assist past 30mph.
    Ideal for the cyclist who pedals looking for a sustainable "keep up with traffic" speed.
    Even moderate drafting should greatly reduce required assist effort.

    Added benefits are:
    Higher efficiency, especially at lower speeds
    Less overheat potential in spite of the higher voltage
    A perfect alternative as an eaBike as opposed to an eBike
    Find a truck or van for substantial drafting
    Find a car of proper height for good overall visibility, use it for moderate drafting, and as a "blocker"
    (Drafting, especially with larger vehicles, does not require being dangerously close)

    Graph is for a Mountain Bike, Road or Race bike should benefit even more!

    3 shunt Controller "switchable" by cutting and adding switch to one or more shunts?
    1 shunt - 11.7Amp - 350w - 20mph motor only = legal
    + shunt - 23.4Amp - 620w - 28mph motor only
    + shunt - 35.0Amp - 820w - 28mph motor only = full power! (Substantial acceleration increase)
    Small inexpensive 15A switches are readily available!
    "Best of all! ... I get to play. ... http://www.bikeforums.net/attachment...&thumb=1&stc=1
    Sorry! ... I'm addicted to improving enhancing.
    With side orders of inspiring enlightening!"

    Acronyms

  5. #5
    Senior Member chas58's Avatar
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    You are a mad man, Dark Angel...

    Quote Originally Posted by DrkAngel View Post
    Ideally, I could fine tune a bike for motor only 20mph but supplies substantial pedal assist to 30mph.
    That is rather like what I did with a 36v Q100. The drawbacks are that it can't climb hills or really do much slow speed high torque work (hey, its a small motor). With a freewheel speed of 29mph, its not going to make it up to 30mph (without me doing 100% of the work).

    On a mountain bike it does about 24mph.
    On a fast road bike it does about 26+ mph.

    The tricky thing is of course that it is hard to get a flat torque curve to give 20mph motor alone, and still provide reasonable assist at 30mph. These motors tend to have torque curves that rise up and the drop sharply once the current peaks.

    Drafting does help, but I get some funny reactions from drivers who aren't expecting to see someone pedaling behind them in traffic (a lot of them obviously want to lose me, while others seem to be patiently confused).

  6. #6
    Senior Member AnthonyG's Avatar
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    Yes, 20 mph is plenty fast enough. I live in Australia and own an Easy Motion Neo Volt electric bike which in Australia is pedal assist ONLY and is capable of 20mph or 32kmh. I used to race bicycles and was capable of 20mph cruising without assist. Unfortunately I got really sick and now have very little exercise tolerance.

    I tried, but I just killed myself in the effort. My electric bike now lets me get some exercise (I'm always pedalling) without killing myself. I was dubious of electric bikes at first because in Australia electric bikes with throttles are only allowed to get up to 25kmh (15 mph) which is a bit lame. By ditching the throttle they are allowed to go a little faster. The EasyMotion Neo volt is limited to 250 watts in Australia.

    Anthony

  7. #7
    Senior Member chas58's Avatar
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    Wow. Sucks about your sickness. I'm glad the ebike thing is working out for you. Now I'm curious if you kept the road bike format or went with the more traditional mountain bike. I built both, but usually ride the mountain bike (it is set up pretty aggresively though, with the handlebars 2" below the seat height).

    Still playing with the road bike. Getting the weight down to about 27lbs and a torque sensing crank are the next steps (as drop bars obviously don't work well with a traditional throttle)

  8. #8
    Senior Member AnthonyG's Avatar
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    The Easy Motion Neo Volt is a folding bike style bike. Its an off the shelf bike and while not my first choice when I started looking it is comfortable and it does fit. The motor gives me plenty of power to head into a wind.

    Anthony

  9. #9
    Certified Bike Brat Burton's Avatar
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    Quote Originally Posted by DrkAngel View Post
    A differing summation of watts required for a mountain bike to maintain various speeds.

    *5mph = 22w
    10mph = 68w
    15mph = 163w
    20mph = 333w
    25mph = 601w
    30mph = 993w
    35mph = 1532w
    40mph = 2247w
    45mph = 3147w
    50mph = 4280w
    * from ebike.ca simulator

    30mph requires almost precisely 300% the energy as 20mph.
    Of course, it does not require 3x the energy per mile.
    163w/15mph = 10.86wh/mile
    333w/20mph = 16.66wh/mile
    993w/30mph = 33.1wh/mile
    Still 30mph require 2x the energy per mile, or ...
    Same ~36V 10Ah battery ...
    15mph = 30+ mile range or - 92.08 miles per kWh = 6 hour cruise time
    20mph = 20 mile range or - 60.02 miles per kWh = 3 hour cruise time
    30mph = 10 mile range or - 30.21 miles per kWh = 1 hour cruise time
    The numbers here pretty much explain why the manufactures claims of a range of 'up to xx km's' is based on a 160lb rider using 'level 1' pedal assist at a constant speed of 20 kph on level ground with no headwind. In the real world actual range is a fraction of the manufacturer's claims because no one I know drives an ebike or any other bike like that.

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