would this huge single stage reduction setup work?

[parajared]

I can't find any posts of people attempting to build a mid-drive this way so I thought I would ask if it would work.

-192kv 80 amp rc outrunner motor
http://www.hobbyking.com/hobbyking/store/__18129__Turnigy_Aerodrive_SK3_6374_192kv_Brushless_Outrunner_Motor.html
-100 amp speedy
http://www.hobbyking.com/hobbyking/store/__20695__Hobbyking_YEP_100A_2_6S_SBEC_Brushless_Speed_Controller.html
-6s 10ah lipo
-11tooth to 148 tooth bicycle ring (the GEBE ring)
http://www.bikeengines.com/shop/drive-rings-36-spoke/

According to the recumbent drive calculator that would put me at about a 17mph top speed. Do you think that would be geared low enough some aggressive hillclimbing? Do you think I would fry something?
http://www.recumbents.com/wisil/e-bent/rc_drive/rc_drive_calculator.asp

 

[Drum]

Hi Para..
Looking at the website for the 148 tooth belt ring, it is obvious that various gas engines can be fitted to drive through that belt / pulley system, so yes, it would work.
Your gearing with that 192 kV motor on 6S is in the ballpark. I haven't looked up the motor so I can't comment on what torque it has so what acceleration you would get, or considered whether the 11 tooth belt pulley could handle the torque (11 teeth is quite small, so the belt has to flex a lot to wrap around the pulley, and there will only be a few teeth of the belt engaged at a time so the load on each tooth will be relatively high).

My worry is in the way the 148 tooth ring attaches to the wheel: it drives by applying a sideways force to the spokes part way along their length. Every time you accelerate the spokes will bend slightly, and straighten again when you let the throttle off.
I expect that good quality, adequately sized spokes would be strong enough not to break under the load, but eventually metal fatigue would weaken the spokes where the load is applied.
This might take years in gentle use on flat paved roads, but for "aggressive hill climbing", especially off road, it would worry me.

I hadn't seen those large belt rings before, and they definitely offer the chance to get a large gearing reduction in one stage, so worth knowing about. I guess the fact that there is a company selling kits using those belt rings with several different gas motors proves that the system is at least reasonably capable.
Dave

 

[parajared]

The motor on the website is rated at 1.6 horsepower so I should probably limit to about 1200 watts (or 55 amps on 6s). 13 tooth would put me at 20mph so I think bordering on the geared too high for a steep uphill jaunt. 4s lipo would put me at a more torque focused 13 mph but I would be pulling a less than ideal 81 amps.

 

[Miles]

I can't find any posts of people attempting to build a mid-drive this way so I thought I would ask if it would work.

There has been discussion though: http://www.endless-sphere.com/forums/search.php?keywords=golden+eagle&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

 

[parajared]

There has been discussion though

Yeah, but everyone's build focuses on high speeds achieved with high cell count batteries, I am trying to have enough torque to climb straight up a tree. Has anyone done a build like that? I have done quite a bit of searching and haven't found anything like that.

 

[nutnspecial]

Based on the proposed watts and gearing, I think it'll have plenty of usuable torque. It should be really similar to my faster/heavier setup in performance 0-20mph, which seems to climb anything you can stay on the bike for.

 

[Hillhater]

Remember..
RC motors are designed to work in a fast air flow for short periods and rarely deliver their theoretical power potential.
So, on a slow bike, it will heat up quick and will burn if you keep loading it up for more than a few mins.
Don't expect to get over 1 kW from the motor.
Also , don't expect Turnigy packs to deliver their spec output either in terms of amps "C" rate !
Personally, I would source a different lower kV motor,..maybe something like the " big block" motor and run a higher voltage, lower current.

 

[parajared]

I fly rc airplanes too:
frequently I fly my 174 gram rc airplane motor at 1500 watts without it even getting warm. I fly pack after pack without any ill effect.
I fly FPV airplanes now that stay in the air for an entire hour and if I stay within specs the motor will not overheat. The specs seem to work for airplanes is my point.

I have read that rc motors like to overheat when attached to e-bikes instead of propellers but I think there is more to it than the fact that 30mph of air isn't blowing across the motor.