26
Mar 2011
by larry

Ebike Excitement Causes “EV Grin”

Thea and I like to go letterboxing (see letterboxing.org) on our ebikes.

I recently increased the power of my Stoked Big Dummy by setting it up to use two 36v batteries in series rather than only the one 36v battery. (“Stoked Big Dummy” means a Surly Big Dummy extra long bike with a Stokemonkey electric motor.) The change required purchasing a more robust motor controller from the fine folks at ebikes.ca. I also had to open up the controller and solder some beefier resistors in there and make some other modifications. But the result has been amazing. My bike is now very responsive and can easily accelerate to 20mph in a few seconds, and go up hills at 15mph without pedaling. Normally in this blog I rail against speed, but I am discovering that this moderate increase in speed increases the utility and safety of my beloved car replacement vehicle. I can now go on single-afternoon 100-mile trips by bike without it being a big deal “tour”. And I can more easily maneuver in traffic and join the flow. True, I’m now using 20 watt-hours/mile rather than my usual 10 watt-hours/mile, but still nowhere near the 1200 watt-hours/mile that a car uses.

I won’t deny it, speed can also be fun. I recently put together an ebike for my daughter. In the photo above you can see that the bike has a big black front hub. That’s the motor. The batteries are in the bag on the bike rack. Her first ride produced in her the legendary “electric vehicle grin”. She said that her bike was “like a car disguised as a kid’s bike”. She instantly recognized that her new ebike would give her a basic freedom that is denied to kids in our society: the ability to use roads for transportation. Kids in our society are taught from the moment they can walk to stay out of the road. No wonder then that kids must rely on parents and school buses for transportation. No wonder we have an obesity epidemic in this country. The ebike, and the EV grin it causes, may change this sad state of affairs.

I thought this recent post to the Endless Sphere ebike forum by icecube 57 captured the “EV grin” phenomena that is currently only shared by hobbyists but may soon be experienced by the general public as ebikes take off. You can read the original post (along with video) here.

“In other news Im very suprised at the power of this motor. My neighor just moved in her bf. I came home to find them socializing with my wife in the garage. The conversation shifted to my bike. He was like ill try it later. I said you are going to try it now. He gave in. I started him off in Grandma mode. (20mph legal restricted) He was excited about that. The controller still dumps 3500-4000w off the line but it tapers off quickly and he proceeded to take my bike up the huge as hill on my street that I will stall on in grandma mode and it took him up the hill without stalling un assisted maintaing about 15mph. Which I cant even do unless I have a running start. He is about 120lbs lighter than me so I can understand it being easier on the motor and controller. He went around the block and came back. He said take this out of grandma mode. He had a grin from ear to ear…Its one thing to ride your own bike but to see someone else riding it with EV grin hauling ass at top speed in traffic like its a motorcycle”

For the record I only have a temporary interest in riding an electric motorcycle, until the grin wears off. My ultimate goal is to build a lightweight (200 lbs.) narrow (42″) slow (20mph) passenger-carrying “car” that falls within the legal definition of an ebike. I couldn’t see myself succeeding with 36v. I can definitely see it happening with a 72v machine.

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  • http://Website joy scout

    Earth day today – and after riding my extra-cycle 20 km – with my kid on the back up and down hills – I’m exhausted – I need electric assist if I’m going to get rid of my car for good. Thanks for the post – it’s inspiring

  • stoney

    Ok you did. I am interested in this as well. I have a stokemonkey on a sun atlas cargo. I believe that I am the first person to do this… I recently was running 48v from a free pack from a friend that died and I am looking to get new batteries. How far can you go on the 72v sla 10ah? And what lithium pack do you have? I hope you respond soon. I have many hills too and pretty much a car replacement and this would seal it for me if it is reliable and structurally safe. Thanks in advance!!!

    • http://knowledgetown.com/newsandevents/ News & Events

      I stopped running my Stoked Big Dummy at 72v because the bike chain kept breaking. 48v is pretty much the max for a Stokemonkey, and also at 48v it’s a good idea to use a larger chain ring so the pedaling cadence is lower. See http://www.ebikes.ca/shop/conversion-kits/stokemonkey/classic-stokemonkey-kit.html. I ended up getting a rear direct drive hub motor that can handle 72v. I wouldn’t recommend using SLA batteries any more. Lithium are better in all respects.

      • stoney

        Yes, I put the 50 tooth on the stoker crank. I may put a bigger chainring on the stoker crank. I want an even slower cadence and more torque. Any suggestions?

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    • http://knowledgetown.com/newsandevents/ News & Events

      I put a 60-tooth chainring on my Stokemonkey which worked well. This was the largest chainring I could find. You can see the 60-tooth chainring in action in this post in which I describe how I attached the Stokemonkey to a fat bike:
      http://bikes-as-transportation.com/behold-the-beast-low-cost-electric-fat-bike-conquers-snow/