Motor arrived in 11 days from Hobby King. Based on a new-to-you test procedure I found on an RC site, I threw together a cheap test stand to be my third hand. Its possible to fry a motor or ESC when you are new to this game (as I am).
http://aircraft-world.com/prod_datashee ... wiring.htm
Todd originally used 36V cordless-drill packs (available from DeWalt and Milwaukee), and I felt that those would appeal to non-technical college students. Also, using higher volts can sometimes mean you need fewer heat-producing amps to do the job. I wanted to use the 28V packs, which were smaller, cheaper, and actually have a higher discharge capacity (the C-rate, meaning Current). Also, both Milwaukee and DeWalt have made long-term committments to ensure continued production of their 28V line.
Just as I was about to buy several barely-used packs from a fellow ES member, I got my hours at work cut. More time on my hands (good) but less money for parts (bad). I have settled on the 6S LiPo packs (22V-24V) for the lower price, and also to get some hands-on experience with LiPo, as I believe RC and LiPo will soon take over a large share of the E-bike market.
I've been told by a friend I will likely only get 13-MPH (21-kph) from a 250-kV motor-winding at 22V with a 1" diameter roller on a 26" wheel (I guess we'll see, should have good hill-climbing ability and low ESC heat, with no synch issues, and should start from a dead stop easily on heavy cargo bikes). I plan to also try an 1-1/4" roller, different kVs and different voltages, both on hills and the flats. I hope to log amp-draw for each. However, if I had started out with a bigger motor and higher kV, I would have always wondered about the smallest motor I considered as acceptable for my goals (63mm diameter, 10mm shaft).
"should" get 20-MPH from a 280-kV, using 6S (22V-24V) with 1-1/4" roller...
I guess I can now retire the stunt-double, which is a 5-oz can of vienna sausage (Visualize an old homeless-looking guy with calipers, wandering through a store measuring cans). Kaiser Wilhelm once said, if you like laws and sausages, don't ask how either of them are made.
Edit: added a list of other possible motors...The first # is the motor diameter in mm, the second # is the length in mm (the internal motor section, the outer motor body is longer), and the third # is the kV (RPMs per volt applied). The black motors are advertised as having better bearings. A higher kV will have a higher top speed while using the same volts, but it will also have more motor/ESC heat at low RPMs.
The first section has 8mm
diameter shafts (I prefer to work with the larger 10mm when possible).
$49 63-59-259 silver
http://www.hobbycity.com/hobbycity/stor ... oduct=4572
$40 50-65-270 black
http://www.hobbycity.com/hobbyking/stor ... oduct=7709
$30 50-65-270 gold
http://www.hobbycity.com/hobbyking/stor ... oduct=5204
$24 50-65-320 gold
http://www.hobbycity.com/hobbyking/stor ... oduct=4913
$56 63-45-330 silver
http://hobbyking.com/hobbyking/store/uh ... oduct=2136
$30 50-65-350 gold
http://www.hobbycity.com/hobbyking/stor ... oduct=2101
$40 50-65-380 black
http://www.hobbycity.com/hobbyking/stor ... oduct=7070
$30 50-55-400 gold
http://www.hobbycity.com/hobbyking/stor ... oduct=2102
$30 50-65-400 gold
http://hobbyking.com/hobbyking/store/uh ... oduct=4914
http://www.scorpionsystem.com/catalog/m ... -4035-400/
$60 63-74-170 black
http://www.hobbycity.com/hobbyking/stor ... oduct=7870
$60 63-74-200 gold (has additional skirt bearing)
http://www.hobbycity.com/hobbyking/stor ... oduct=3890
$45 63-64-230 blue
http://www.hobbycity.com/hobbyking/stor ... oduct=4188
$60 63-64-230 black
http://www.hobbycity.com/hobbyking/stor ... oduct=7710
$50 63-64-245 blue
$56 63-54-250 gold (has additional skirt bearing)
http://www.hobbycity.com/hobbyking/stor ... oduct=5144
$44 63-64-280 gold (has additional skirt bearing)
http://www.hobbycity.com/hobbyking/stor ... oduct=2097
$45 63-54-295 blue