Electric Bikes - R/C plane electric motor for an e-bike?

http://www.astroflight.com/index.php?main_page=product_info&cPath=5&products_id=80

A motor like that puts out tons of power, and weighs less than 2 pounds. I'm sure it has almost no torque, but still, I cant help but wonder if you could make decent use of the thing if you hooked it up to your inner chainring and gave it the benefit of your full gear range.

thoughts?

if these motors can be built to weigh so little, why do the motors most people use here weigh so much more to accomplish similar power ratings?

Im assuming that motor is used for big/heavy planes....and it probably does not have the correct manufacturing or torque to power a bicycle . Also it may not get anough cooling effect when used on a bicycle at 20 mph...compared to a plane several 100ft in the air going 40 + mph .

Sure you can, loads of guys are doing this kind of thing over at endless-sphere. Most RC setups are being documented in this subforum:

http://www.endless-sphere.com/forums/viewforum.php?f=28

Including mine:

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=22777

Sure you can, loads of guys are doing this kind of thing over at endless-sphere. Most RC setups are being documented in this subforum:

http://www.endless-sphere.com/forums/viewforum.php?f=28

Including mine:

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=22777



friction drive setup ? isnt there alot of disadvantages to that ? like slipping in wet weather / wet roads, driving over pebbles/rocks...where on the tire itself , etc ? also...I would imagine the costs for a RC setup vs a rear hub motor, would be simliar ?

I would have to think a brushless rear hub motor is more efficient and more reliable then a RC motor in a friction drive setup.

friction drive setup ? isnt there alot of disadvantages to that ? like slipping in wet weather / wet roads, driving over pebbles/rocks...where on the tire itself , etc ? also...I would imagine the costs for a RC setup vs a rear hub motor, would be simliar ?

I would have to think a brushless rear hub motor is more efficient and more reliable then a RC motor in a friction drive setup.

IMO it all depends on your use. In my case I wanted my bike to still be a bike. Thus, I wanted ultralight and something that did not interfere with the chainline and or a cumbersome hub (weight and drag when not in use). Not being able to use it in the rain is not a huge issue, I'll just pedal in that case. But, I at least have that option. My previous hub motor bottled it after the 2nd wet ride leaving me to pedal that led brick home 30km.

Others have put RC setups in their chainlines and/or with reduction units etc. It all depends on your technical skill and willingness to fiddle with things which is why I went with a commercial offering. I just want something that slaps on and will work without all the weight of the typical offerings. As for friction drive and gravel etc, in my case my city is pretty clean and I commute on streets so its a non issue.

The costs can vary greatly so its hard to draw a comparison unless your talking about specific kit. As for hubs being more reliable. I simply don't trust cheaply made hub motors for 200USD to get the job done. If the RC fails, no biggy. If for any reason I did go back to a hub setup I would probably only trust something like a Heinzmen.

I also can't compare the efficiency as I don't use the system full time as I did the hub (only due to weight). I can say that my current 1kg battery gets me about 40km with fairly common use. Previously my 8kg battery with hub motor would get me about the same, granted it was a much more powerful solution.

It all depends on your needs. If I only commuted 10km each way a hub would probably be reliable. But to be honest. I hated my bike with that setup as it felt like a tank and I now feel I have the best of both worlds being able to have everything I want in one bicycle. There's not a lot of storage room for multiple bikes in my part of the world:D

I'm betting the bike(s) he's putting the different type of motors on them are $1500+ bikes with carbon fiber in them...
Yeah, for really expensive light bikes that weigh 15lbs or less, a hub motor and batteries would make it three times the weight and unridable to those who are used to fast, light bikes..

For the majority of us that have 40lb, $100 bikes the added weight doesn't make as much of a difference.
I could be wrong about the poster's bike in terms of cost/weight, but usually it's the case with those that say friction drive works well for them..
A 15lb. bike being pulled by a little RC motor and small batteries will work alot better than a 40lb. one with the same setup.
Correct me if I'm wrong.

umm, nope both bikes in my sig are steel and I'm 250lbs, 6'5 to boot and this little friction drive works fine for me. But as I have said a few times. It depends on what you want, and what your potential use is.

I'm betting the bike(s) he's putting the different type of motors on them are $1500+ bikes with carbon fiber in them...
Yeah, for really expensive light bikes that weigh 15lbs or less, a hub motor and batteries would make it three times the weight and unridable to those who are used to fast, light bikes..

For the majority of us that have 40lb, $100 bikes the added weight doesn't make as much of a difference.
I could be wrong about the poster's bike in terms of cost/weight, but usually it's the case with those that say friction drive works well for them..
A 15lb. bike being pulled by a little RC motor and small batteries will work alot better than a 40lb. one with the same setup.
Correct me if I'm wrong.

For the most part I agree with you but still it is something I have considered. Like the lipo batteries they are now common place in the RC world but not nearly as much in ebiking (yet). But for those who have ventured t.o lipo are crazy about them. I think the RC motors will be the same way eventually. The problem for now is they are mostly direct drive and very high RPMs. This generally requires a great deal of home grown desin work. Couple that to finding a proper controller and throttle and it's more then most of us want to or can handle. That being said though I think it would be a great advancement if someone would couple these motors to a good gear box with easy mounting for ebikers.

Bob

For the most part I agree with you but still it is something I have considered. Like the lipo batteries they are now common place in the RC world but not nearly as much in ebiking (yet). But for those who have ventured t.o lipo are crazy about them. I think the RC motors will be the same way eventually. The problem for now is they are mostly direct drive and very high RPMs. This generally requires a great deal of home grown desin work. Couple that to finding a proper controller and throttle and it's more then most of us want to or can handle. That being said though I think it would be a great advancement if someone would couple these motors to a good gear box with easy mounting for ebikers.

Bob

Its the high rpms that are the big issue.. This will be hooked up to my inner chainring. How much effort am I going to have to expend just to keep the motor spinning at such a high rpm while I'm pedaling around town without boost? And is that going to make a ton of noise?

For the most part I agree with you but still it is something I have considered. Like the lipo batteries they are now common place in the RC world but not nearly as much in ebiking (yet). But for those who have ventured t.o lipo are crazy about them. I think the RC motors will be the same way eventually. The problem for now is they are mostly direct drive and very high RPMs. This generally requires a great deal of home grown desin work. Couple that to finding a proper controller and throttle and it's more then most of us want to or can handle. That being said though I think it would be a great advancement if someone would couple these motors to a good gear box with easy mounting for ebikers.

Bob
What type of batteries do you guys use? I come from the rc hobby, and tell you lipo batts are killer compared to any other (older) batts in the hobby. They are "more" volatile if mishandled, but that is also debateable. They flame up and make fumes, nicads/nimh go off like shotguns, so it's kind of a wash. Li-ion batts are getting more and more popular, and don't do either of those things when misused or punctured. They have less voltage, but safer, and you just motor up to get back the performance.

Its the high rpms that are the big issue.. This will be hooked up to my inner chainring. How much effort am I going to have to expend just to keep the motor spinning at such a high rpm while I'm pedaling around town without boost? And is that going to make a ton of noise?

Somewhere in your chaining system you need to have a freewheel that disconnects your peddling from the motor. I have built 3 bikes so far and 2 of them used a single chain for both peddling and motor. On the last build I used 2 cheap crappy motors mounting them in the "V". I used a seperate chain for the motors and peddles. But I still used freewheels.

What ever you build and however you mount it be sure to use a freewheel that will protect you from the motor. I rode one time without this protection because my wife's bike had a damaged freewheel. So I popped mine off and installed it on her bike. I rode with her for one bloce without a free wheel. My foot slipped off the peddle and the peddle beat the crap out of my leg until the motor stopped. Trust me you need to use a free wheel to seperate you from the motor. IF you do it all correctly you can peddle without any drag from the motor because it is functionally disconnected from the system when not powered.

Bob

What type of batteries do you guys use? I come from the rc hobby, and tell you lipo batts are killer compared to any other (older) batts in the hobby. They are "more" volatile if mishandled, but that is also debateable. They flame up and make fumes, nicads/nimh go off like shotguns, so it's kind of a wash. Li-ion batts are getting more and more popular, and don't do either of those things when misused or punctured. They have less voltage, but safer, and you just motor up to get back the performance.

Many ebikers (mostly newbies) are still running SLA packs. But most people soon relize the value of stronger lighter power packs. Most turn to lifepo4 packs while some will eventually go lipo. There is a constant question as to weather the risk of lipo is truely worth the added power per pound value over lifepo4. Being a lifepo4 user for 2 years (still use an old SLA now and then too) I am happy for now but when they die I may consider lipo for a test.

Bob

I made a mistake in my above post.. I meant lifepo4 when I wrote li-ion. How many cells (volts) are the batteries they use in these bikes? I guess if I had my choice to sit over a lipo or lifepo4, I'd choose the lifepo4 pack :) Especially if I were building my own rig, then I could use the safer battery and choose a higher powered motor to offset the voltage difference. Guess I'll have to research some of these bikes and see what/how ya'll are building them. Sounds interesting.

Somewhere in your chaining system you need to have a freewheel that disconnects your peddling from the motor. I have built 3 bikes so far and 2 of them used a single chain for both peddling and motor. On the last build I used 2 cheap crappy motors mounting them in the "V". I used a seperate chain for the motors and peddles. But I still used freewheels.

What ever you build and however you mount it be sure to use a freewheel that will protect you from the motor. I rode one time without this protection because my wife's bike had a damaged freewheel. So I popped mine off and installed it on her bike. I rode with her for one bloce without a free wheel. My foot slipped off the peddle and the peddle beat the crap out of my leg until the motor stopped. Trust me you need to use a free wheel to seperate you from the motor. IF you do it all correctly you can peddle without any drag from the motor because it is functionally disconnected from the system when not powered.

Bob

Bob, Thanks for this sensible suggestion. I had actually planned out almost all of the components over the last couple of days, and am very glad I didn't go ahead and buy anything. To be honest, I'm not terribly scared to go without the freewheel, as I've ridden fixed gear bikes for years, but now that I think about it, it would be much more refined to have one. The only problem is that when I give it juice, im going to have to tip in slowly on the throttle. If i'm peddling at a high rpm and floor it, it will be a bit violent when the freewheel locks up. Can't wait to show you and the rest of the internet my finished E-Scalpel this summer!

Bob, Thanks for this sensible suggestion. I had actually planned out almost all of the components over the last couple of days, and am very glad I didn't go ahead and buy anything. To be honest, I'm not terribly scared to go without the freewheel, as I've ridden fixed gear bikes for years, but now that I think about it, it would be much more refined to have one. The only problem is that when I give it juice, im going to have to tip in slowly on the throttle. If i'm peddling at a high rpm and floor it, it will be a bit violent when the freewheel locks up. Can't wait to show you and the rest of the internet my finished E-Scalpel this summer!

Stud, I think your missunderstanding how it should all work but lets first go back to your comment agout riding a "fixed gear bikes". I am not an expert on bike but I have never heard of a bike that didn't have some kind of freewhell on it. To be honest until I started playing around with ebikes I hever though much about and I'm guessing a lot of people don't. So are you 100% sure these bikes didn't have a freewheel on them. Most fixed gear bikes have a freewhell in the rear hub while I think some BMX bikes have a freewheel in the crank sprocket. Think about it this way....could you ever stop peddling while the bike was moving forward? How could you ever come to a stop?

In my opinion an ebike should have a freewheel to seperate the motor from the rear wheel and a freewheel to seperate the peddles from the rear wheel. This offers a double protection in the unlikely event the motor freewheel fails. And yes they do fail and can actually lock up in the engaged position. On my current bike I have a freewheel on the Nuvinci hub that connects to my peddle chain. I then have a freewheel on each motor. In this setup I am 100% protected. Freewheels are a cheap protection insurance.

As I remember your using an existing bike so it likely already has a freewheel on the rear hub. So all you need to do is incorparate a freewheel somewhere into the motor drive.

Bob

Stud, I think your missunderstanding how it should all work but lets first go back to your comment agout riding a "fixed gear bikes". I am not an expert on bike but I have never heard of a bike that didn't have some kind of freewhell on it. To be honest until I started playing around with ebikes I hever though much about and I'm guessing a lot of people don't. So are you 100% sure these bikes didn't have a freewheel on them. Most fixed gear bikes have a freewhell in the rear hub while I think some BMX bikes have a freewheel in the crank sprocket. Think about it this way....could you ever stop peddling while the bike was moving forward? How could you ever come to a stop?

In my opinion an ebike should have a freewheel to seperate the motor from the rear wheel and a freewheel to seperate the peddles from the rear wheel. This offers a double protection in the unlikely event the motor freewheel fails. And yes they do fail and can actually lock up in the engaged position. On my current bike I have a freewheel on the Nuvinci hub that connects to my peddle chain. I then have a freewheel on each motor. In this setup I am 100% protected. Freewheels are a cheap protection insurance.

As I remember your using an existing bike so it likely already has a freewheel on the rear hub. So all you need to do is incorparate a freewheel somewhere into the motor drive.

Bob

Bob,

I'm not sure where your from, but if you go to a city where there is a hippie bike culture, like NY, Boston, Denver, San Fran, etc, look closely and you will see plenty of kids riding around on the fixed gear bikes. I have one. I built a wheel from a white industries ENO hub and converted an old road bike that had vertical dropouts. It's a freewheel on one side, and a fixed gear on the other, and yes, you can't ever stop pedaling with the fixed gear, and you can ride backwards if you choose. A cool side effect is that when you trackstand you can rock back and forth. It's good for training your form (in small doses), especially your high-rpm smoothness on downhills. I am an extremely high rpm rider. I never really use it though, except for the odd jaunt around the park. I even know some people who have no brakes on their bikes, and stop by spastically shifting their weight forward and snapping their legs back to lock the rear wheel. Now THEY are dumbasses!

My only concern with using a freewheel is having a violent "knock" when I spool up the motor from rest and the pawls engage. This will certainly shorten the life, or even cause the very failure that the freewheel is supposed to prevent. To avoid it, I'll have to get in the habit of stopping pedaling before hitting the gas. In a worst-case scenario where my freewheel has failed and my motor's throttle has decided to floor itself, still, the bike has disc brakes which will easily overcome the torque of the motor for long enough to slow down and jump off.

Bob,

I'm not sure where your from, but if you go to a city where there is a hippie bike culture, like NY, Boston, Denver, San Fran, etc, look closely and you will see plenty of kids riding around on the fixed gear bikes. I have one. I built a wheel from a white industries ENO hub and converted an old road bike that had vertical dropouts. It's a freewheel on one side, and a fixed gear on the other, and yes, you can't ever stop pedaling with the fixed gear, and you can ride backwards if you choose. A cool side effect is that when you trackstand you can rock back and forth. It's good for training your form (in small doses), especially your high-rpm smoothness on downhills. I am an extremely high rpm rider. I never really use it though, except for the odd jaunt around the park. I even know some people who have no brakes on their bikes, and stop by spastically shifting their weight forward and snapping their legs back to lock the rear wheel. Now THEY are dumbasses!

My only concern with using a freewheel is having a violent "knock" when I spool up the motor from rest and the pawls engage. This will certainly shorten the life, or even cause the very failure that the freewheel is supposed to prevent. To avoid it, I'll have to get in the habit of stopping pedaling before hitting the gas. In a worst-case scenario where my freewheel has failed and my motor's throttle has decided to floor itself, still, the bike has disc brakes which will easily overcome the torque of the motor for long enough to slow down and jump off.

Stud, OK, now I understand but one question. When you say "It's a freewheel on one side, and a fixed gear on the other" are you saying it's a flip/flop hub, whereas, there is a sprocket (freewheel or not) on the left and righ side and you flip the wheel to chage back and forth?

Certainly I am not the type of rider that you sound to be. But I would not be overly concerned about the freewheel. I am beting that you will never notice the freewheel engaging. While the motor spools up quickly because it's not seeing a load until it catches up to you the actual emgagement of the freewheel is very smooth. This being said though you might want to consider using a better quality freewheel with 3 or more dogs of engagement. I have always used the cheapos with 2 dogs and sell for 10 to 20 bucks. But with my riding I have never lost a freewheel. The added dogs will not make it smooth but stronger. I honestly don't think you will need to stop peddling when spooling up the motor....you will not feel the engagement. But once you have the bike setup and running I hope you will get back to us with the results. I'll be interested in hearing how the freewheel works for you. What size freewheel sprocket are you thinking of?

Bob