Friction Drive Hill Climbing? Lower kv?

[evblazer]

Been reading about stuff for the last two days and I guess what I'm stuck on is if a friction drive would be ok with climbing a hill? Using the outrunner as the drive wheel as in http://endless-sphere.com/forums/viewtopic.php?f=28&t=16550 is really appealing.
Trying to do calculations it seems at the size of the motor vs a 26" wheel it wants to spin pretty fast. ~43mph with the setup in the linked 320kv motor. Of course that is no load but will the motor happily go say 5 minutes or so pushing 40 amps at a low rpm while climbing a large hill? On the flats I'd mostly leave it in the off position. I was liking it because it might be the one system I can easily use on any of my bikes which have 3 different wheel sizes: 559, 622, 406.
I was thinking a Hyperion Z4045 with 14turns which is 236 kv and using either a light 24v pack or the existing 24v thundersky pack I have and driving it with a castle controller and rc throttelizer. Which would give me 5664 rpms at 24 volts overall and a top speed of 31.8mph at max rpms of the motor with no load.

 

[EVTodd]

Keep in mind that wheel size has no effect on top speed with a friction drive setup. If you do the calculations with or without figuring in the wheel you get the same results.

I don't know the diameter of the motor you are looking at but to get 31.8 mph at around 5600 rpms you would need a roller that is around 1.89"

From personal experience I think you want to keep the roller as small as possible if you want to climb hills really well. My setup with a towerpro 5330 motor (no longer being sold btw) running at 36 volts and a 1.25" roller climbs hills like a maniac. I can't believe how hard it pulls and I'm not a small guy.

 

[evblazer]

Ah yeah your right I don't know why I mentioned tire size I noticed that when I changed the tire size in my sheet it basically jsut cancelled out and nothing changed.
I'm looking at a 1.89" (48mm) motor. I'm not really going for speed but I wanted to make sure hill climbing was a real possibility so that is good to confirm. No overheating worries as long as I keep the amps in line?

 

[EVTodd]

I don't want to say there are no overheating worries because that's probably not true. My motor gets fairly hot if going uphill for a long period of time. I've never had a problem with it but it's something to watch for sure.

Of course a lot depends on your setup. I think mine just happens to be pretty easy on the motor most of the time.