Brainstorming for a commuter bike

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Gaber
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Brainstorming for a commuter bike

Constraints:
~$2K
-----------------
1. Bad roads (pot holes and "ripples" due to massive bus traffic)
2. 11 mile daily commute round trip
3. 45 mph posted speed limit road (unavoidable)
4. I'm not tall -- 5'7
5. Not much experience with real motorcycles (2 50cc motor scooters)

I originally was considering a scooter conversion, or just buying the EVTA R-30 or X-treme 3100. The hub motor seemed elegant at first. Now I'm worried about the tiny scooter wheel dropping into a pothole -- experience tells me the wheel can take quite a beating when that happens. Also, I could probably get away with not having to register or get a special license if my scooter maintains the 50cc look. Anyway, the idea of moving onto a motorycycle is more inspiring to me -- so, unless someone talks me back into the scooter idea, let's focus on the motorcycle conversion.

I would love to get a cheap and readily available Ninja ( ~$1K and sell the engine like this guy http://www.evalbum.com/1955 ) but I'm worried about the 30.5" seat height because I am not tall. I want my new bike to be light and nimble and safe. The fact that the fairing is there already to conceal the batteries visually (and protect from the elements!?) is a big plus for me.

I've read the posting on the Virago as a suggested model. But would the exposed innards be a hazard (in addition to being ugly).

Any suggestions for a project that requires minimal modification? In particular I am hoping to avoid welding -- though I can get access to a shop if I really have to.

This is my first conversion project. Am I being overly ambitious in trying to make a reliable commuting bike?

Thanks for reading!

Gabe

reikiman
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Re: Brainstorming for a commuter bike

Seems you have a pretty good grasp on this. To build your own on that budget will require some familiarity with metal working and maybe welding.

Did you see this: http://www.electricmotion.org/ ?? As I recall the bike bought "new" as a glider was $600 plus $1000 or so for parts.

I have a bunch of resources here: http://www.7gen.com/website-categories/electric-motorcycles

spinningmagnets
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Re: Brainstorming for a commuter bike

David H and I have both owned a Honda 250 Rebel in its gasoline form. I can assure you, if you find one for a good price, the seat height will be very comfortable for you. (the 450 Rebel has tubeless tires and a slightly larger frame that could hold larger batteries, yet still with a low seat height)

I have stumbled across a couple Rebel EV conversions, and I'm sure if you searched specifically for them there are several. The Rebel is still being made, stop by a Honda dealer, and sit on one for free.

Consider 72-volts (12V X 6) higher voltage is desireable, but controllers over 72-volts are significantly more expensive, and packaging more 12V batteries than 6 is problematic. 11 miles is easy, size the batteries amp/hour size to allow a range of 30 miles, but plan on charging at work also. If you use half of your batteries capacity, they might last 4 times as long

It is reasonable to expect about a years use from the batteries if they are not too heavily deep-cycled. If sized for 50% depth of charge (DOC) they should provide a reasonably cost-effective life cycle. When they die, you could upgrade to the more expensive lithium batteries, and then you would have significant range from the bike and/or it could be much lighter.

Some experimentation is being done by some clever people on developing very small series-hybrid trailers, as an occasional range-adder for an EV. This creates a home-made "plug-in" series-hybrid, and the on-board battery pack can then be small, inexpensive and easy to package.

If the on-board pack is 109V (12V X 9) then its possible to use a small 120V generator thats been properly adapted.

reikiman
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Re: Brainstorming for a commuter bike

Shoulda mentioned the Rebel, yeah it's pretty low and comfortable.

One plus point for the Rebel is the swing arm has enough space on it to mount a Perm or Etek motor ON the swing arm. That would leave more room in the former motor cage for batteries. To see the mounting method get a copy of El Chopper ET as it goes over one EV conversion method for the Honda Rebel.

spinningmagnets
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Re: Brainstorming for a commuter bike

Here's a 5-minute part-one of a several-part Rebel EV conversion, it will give you an idea of what you're in for regardless of the donor cycle you end up choosing.

http://www.youtube.com/watch?v=G7wid_8k_7k&feature=PlayList&p=3E8CCDDFD9EF6D56&playnext=1&playnext_from=PL&index=24

Gaber
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Re: Brainstorming for a commuter bike

Hey guys, thanks for the replies!

The eMoto bike is interesting. I hadn't considered building the bike from all new parts -- I guess I figured I could slim down the price a bit by buying a used bike. This is an interesting option to consider

I like the Rebel too but I'm thinking in a new direction. Read on...

*************

This weekend, I took a field trip out to a salvage yard in Baltimore just to poke my head around and see if it might be a good resource for getting parts and advice. The guy was very nice and seemed to genuinely want to help, but initially was very discouraging about the idea of an electric conversion. He seemed to think that a lot of claims online are quite exaggerated or even photoshopped. And he also says a few of his customers had some outright failures in the process.

Anyway, I'm not completely dissuaded, but I've emerged from a few days of thought with three new mantras:

(1) Absolute minimal modification
(2) Lots of calculating and re-calculating
(3) Ask questions to the experts before spending money

(1) I'm convinced that because I don't have the resources of a R/D team (and not much experience working on bikes!), I shouldn't attempt any major re-designs. I want to aim for the same weight/weight balance as the original bike, same suspension, as much of the same stock parts, etc.

As for (2) and (3), I have a calculation to do and a question to follow: Motivated by weight issues (and style too), I have been looking closely at converting an older/vintage (salvage guy recommends 1989 or older for registration in MD without inspection) Honda/Kawasaki/Yamaha dual-purpose bike with an engine size less than or equal to 250 cc. For instance:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=120402954749

-or-

http://cgi.ebay.com/ebaymotors/Vintage-1974-Honda-Trail-Street-Bike-original-owner_W0QQitemZ160325195976QQcmdZViewItemQQptZUS_mo...|39%3A1|240%3A1318

Since I don't want to go much faster than 45, I was shooting for a top speed of 55. To achieve this, I was thinking of going for a 48V system with the EMC-R motor with a ~4:1 gear ratio corresponding 55mph at a max loaded RPM of 3000:

http://www.electricmotorsport.com/store/ems_ev_parts_motors_etek-r.php

Now my question is about the batteries. I want LiFePo4, I think, to keep the bike close in weight to the original design. 15 cells of the 3.2V 40Ah type, in series, would give me ~2kWhr (and I think this could take care of my 11mi daily commute no problem?)

http://www.electricmotorsport.com/store/ems_ev_parts_batteries_thunder_sky.php

However, will they support the kind of current that my system will be drawing? This website says they can do 120A max:

http://www.evpower.com.au/-Thunder-Sky-Lithium-Ion-Batteries-.html

but the EMC-R can run at 150A continuous. Do I need something else? Also, am I right in matching the nominal voltage of the batteries to the voltage rating of the motor? (I realize that the fully charged battery pack my register a bit higher..)

********

Final Q: I don't have a garage, but my house has a nice backyard and some space in the gravel driveway. I was considering working on the bike outside (while the good weather holds) and storing it in a shed like this:

http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10051&catalogId=10053&productId=100494643

Sound crazy?

Thanks again for the help!

reikiman
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Re: Brainstorming for a commuter bike

(1) Absolute minimal modification

I like that, and wish that had come up in my preflight meditations. I have an el Chopper ET project in my garage that's been left incomplete for the last four years, because it's such a drastic modification of the frame. If I'd left it with minimal modifications the bike could have been running years ago.

Anyway..

The other angle to whether to buy an old bike or a new bike is that the new bikes have better frame designs and may be easier to find parts for.

Another advantage of LiFEPO4 is being able to utilize more of the AH's in the battery. If you had SLA pack of 40AH you'd only be able to practically use 20AH.

Have no idea about those cells capacity for delivering amps, but there are others on the site who do. But if you supply fewer amps to the motor than it's rated for it will simply have less power. It won't hurt the motor to give it fewer amps than it's rating.

As for voltage, electric motors are usually forgiving about being overvolted.

It's common to quote a battery pack voltage by it's nominal voltage rating. But fully charged the pack will have many more volts than the nominal rating.

spinningmagnets
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Re: Brainstorming for a commuter bike

You have clearly done some good research, and have realistic goals! I haven't made one yet, but I have a running file for my own reference should the opportunity present itself.

If you want an easy conversion the thing to do is make up a cardboard and duct-tape replica of the motor you want to use, and then compare it to the candidates you want to convert.

The major benefit of the Rebel is that it has a long swingarm, and as a result it has some room in front of the rear tire, so the motor can be mounted directly on top of the swingarm. As you hit a bump, and the swingarm moves up and down, a frame-mounted motor has a slight change in chain slack, and I have seen several different types of spring-loaded slack tensioners (on the bottom half of the chain, the top half is always tight).

I have toyed with the idea (if I found myself with lots of spare time) of collecting a list of Year, Make, and Models of dual-purpose motorcycles that have the longest swingarms, and are thus the best candidates for a cheap easy conversion. The motor you have chosen is very appropriate, and I would like to request that as you look at various models, you may find several that would work, but of course decide on the best one...please record for the rest of us all of those YMM's that would work?

Best of luck!

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