I have asked a number of vendors of hub motors, for data sheets or performance charts on their motors. From those, I have put together a few lists of how much torque a motor produces at full throttle at various speeds, how many amps it consumes, how efficient it is, etc. This list is as accurate as the data sheets they sent. Caveat Emptor. I found this a useful guide in deciding what hub motor to buy.
I have also put together a list of what features each vendor offered with their hub motor (Controller, thumb throttle, battery charger, that cute little twin LED headlight with a power gauge on it, etc.). It's data taken from their ads - I listed the Ebay ad in the cases where I found them on Ebay. In a few cases, they told me in emails that they did or did not offer a certain feature or part. Some Ebay ad numbers are now expired, but will still come up. In that case, the vendor usually has a new ad out with the same products and features - click on "See other items" in the expired ad.
I'm mostly interested in the 48V 1000W motors, so that's what most of these are. There are other motors I haven't listed, of course.
Nearly all the data sheets they sent me, only listed full-throttle performance, and only for the upper-RPM range. So you can't tell directly from this, how a motor will perform during a half-throttle cruise, how efficient it will be then, etc. But you can tell if a motor has the oomph to push you up to 25mph or whatever.
I also did some tests on my own bike (Trek 7500, 700c wheels, 3/4" tall 116psi tires), riding down a long hill (asphalt paved bike path, no wind that day, sweet) and finding what speed the bike kept a steady speed while coasting. Then measured the slope of the hill, and worked out how much push, and how much torque, and how many watts, it would take to keep the bike going at that steady speed on flat ground with my 30# bike and my 265# lard @ss in the saddle. No electrics, of course, the bike isn't converted yet, so I'll have to figure in that weight later. But this gives me an interesting look at roughly what I can expect.
On a 1.71 degree slope, the bike coasted at a steady speed of 23.1 miles per hour, according to a speedometer I calibrated pretty carefully. With an all-up weight of 295 pounds, that means that the forward push from gravity at that speed was 8.806 pounds, and was being exactly balanced by the wind drag, tire rolling resistance, etc. of me and the bike. That much push at that speed works out to 298.3 foot-pounds per second, which is 0.542 horsepower, or 404.5 Watts. Nobody has checked these figures yet except me, and I could easily have made mistakes. Please let me know if you find any!
Bottom line, it would take 404.5 Watts pushing against the ground, to keep me and the bike going at 23.1 mph on flat ground on that kind of surface with no wind. A motor operating at, say, 70% efficiency, would need 577.9 Watts of electricity from the battery to go at that speed with me on that bike. Looks like the 48V motors I have data sheets for, could do that easily without opening the throttle all the way... once we got up to that speed, of course. This looks promising!
Hope you all find them usable. Shoot me any questions or comments you may have.