Friction drive outrunner setup. New DJ bike.
- Thread starter EVTodd
- Start date
A quick report on my build if anyone is interested.
I now have over 200 miles on this setup and (knock on wood) haven't had any problems to date.
The Towerpro 5330 motor is holding up great and, believe it or not, still has the original bearings in it. The tire has almost no wear from the friction roller and the sliding mechanism is working very well. I'm glad I didn't give up on the idea and a big thanks goes to Rkosiorek for bringing that whole concept to our attention.
My 3 bosch fatpacks are still holding up great too. In fact, I seem to be getting just slightly less range with this setup than I was with my Kollmorgen drive. I'm a bit shocked by this actually. I expected to get a lot less range with an outrunner but hey, that's cool.
My original plan was to buy a second motor to throw in my panniers as a spare but I found out this week that Towerpro no longer makes this model. It is nice, however, to see all of the improvements in the newer HXT and Turnigy motors so I'll probably just grab one of those as a spare.
I do have one questions though. How hard are the shafts on these newer HXTs and Turnigys? The Towerpro motor had a 8mm shaft and all the equivalent motors are 10mm. I'll have to machine the end down to fit in my friction roller shaft and I'm hoping they're not hardened.
I now have over 200 miles on this setup and (knock on wood) haven't had any problems to date.
The Towerpro 5330 motor is holding up great and, believe it or not, still has the original bearings in it. The tire has almost no wear from the friction roller and the sliding mechanism is working very well. I'm glad I didn't give up on the idea and a big thanks goes to Rkosiorek for bringing that whole concept to our attention.
My 3 bosch fatpacks are still holding up great too. In fact, I seem to be getting just slightly less range with this setup than I was with my Kollmorgen drive. I'm a bit shocked by this actually. I expected to get a lot less range with an outrunner but hey, that's cool.
My original plan was to buy a second motor to throw in my panniers as a spare but I found out this week that Towerpro no longer makes this model. It is nice, however, to see all of the improvements in the newer HXT and Turnigy motors so I'll probably just grab one of those as a spare.
I do have one questions though. How hard are the shafts on these newer HXTs and Turnigys? The Towerpro motor had a 8mm shaft and all the equivalent motors are 10mm. I'll have to machine the end down to fit in my friction roller shaft and I'm hoping they're not hardened.
gunthn
100 W
Storm said:A single sided cone roller with the motor mounted to a sliding mount on a rack, CVT?
Any opinions weather or not a oneway bearing would work as a roller by itself on a skinny 700c wheel? I have never touched a oneway bearing so I don't know how tall or wide they are.
I am wondering how hard it would be to shift the motor under power?
It is not easy to shift a nuvinvci under power and under high power it will hardly move.
The motor would need to move on two planes in a similar way to a dérailleur? Up and over.
EVTodd
Thank you for the report.
I am working on similar setup with sliding movment. Mechanicly I have alredy installed and seems to work good as you and rkosiorek explain in details.
I was able to test with the cordless drill only as I am waiting for HXT 63-64-B 230Kv Outrunner. I let you know how hard the shaft is. My plan is to drill hole in the shaft and insert 1/8 hardened pin so it will slide in the EV roller. Also I will have to turn down the shaft to 8mm to inset to ev roller.
Thank you for the report.
I am working on similar setup with sliding movment. Mechanicly I have alredy installed and seems to work good as you and rkosiorek explain in details.
I was able to test with the cordless drill only as I am waiting for HXT 63-64-B 230Kv Outrunner. I let you know how hard the shaft is. My plan is to drill hole in the shaft and insert 1/8 hardened pin so it will slide in the EV roller. Also I will have to turn down the shaft to 8mm to inset to ev roller.
Grinhill
10 kW
What they call a hardened shaft isn't very hard. You can drill dimples on them with regular steel drill bits. I don't know whether it would be machineable.
I note that you can buy the shaft as spare parts, if you need to play around with one.
I note that you can buy the shaft as spare parts, if you need to play around with one.
Grinhill said:
The shaft on the TowerPro motor was also very easy to drill and machine. I don't think they called that one hardened though. I would just buy another motor to play with but every time I find one I want on HobbyKing they're sold out.
wiredsim
10 W
Sorry to bring this thread back up again for this question, but I didn't want to make a whole new thread just for this. Would it be possible to use a outrunner directly against the tire? Maybe my noob is showing but my inspiration was a picture from John in CR's thread:
Just imagine the motor a little closer to the wheel and directly pressing against the wheel. I can think if a couple of easy mounting methods that would allow you to have it pivot with cable control.
If needed one could put some friction enhancing material on the outside of the casing also.
Am I smoking something or is this feasible at all? I know friction drives aren't the most sexy of designs, but it would be dirt cheap..
Just imagine the motor a little closer to the wheel and directly pressing against the wheel. I can think if a couple of easy mounting methods that would allow you to have it pivot with cable control.
If needed one could put some friction enhancing material on the outside of the casing also.
Am I smoking something or is this feasible at all? I know friction drives aren't the most sexy of designs, but it would be dirt cheap..
etard
100 kW
Your smoking crack, cuz cheap IS sexy!! And so are friction drives. 8)
Anyway, this is exactly what I had planned for my friction drive. In fact I could sell you my whole setup. Basicly I have an outrunner with a kv of I think around 300kv, that means that at 36 volts minus losses it will spin at somewhere around 9,000rpm. Then I bought a hardened shaft and replaced the stock one with an extended version (about 9") so that I could put the EV Warrior roller on the shaft and still have support on the other side so as not to blow out my motor bearings. Then you just mount this on the rear triangle and presto you have an outrunner directly mounted to the wheel. Mine is feared so that a 26" tire will go about 25mph. I never did mount mine (ashamed I am) so you are welcome to make me an offer on this setup. Pm me for pics. For simplicity sake, it doesn't need to slide, but if I were going that route I would try to get a bike with both rear brake bosses for cantilevers and disc mount capability. This way I could mount the outrunner on the brakes bosses and have disc rear brake. It really is a simple solution to the gearing issues, and very lightweight at the same time.
Anyway, this is exactly what I had planned for my friction drive. In fact I could sell you my whole setup. Basicly I have an outrunner with a kv of I think around 300kv, that means that at 36 volts minus losses it will spin at somewhere around 9,000rpm. Then I bought a hardened shaft and replaced the stock one with an extended version (about 9") so that I could put the EV Warrior roller on the shaft and still have support on the other side so as not to blow out my motor bearings. Then you just mount this on the rear triangle and presto you have an outrunner directly mounted to the wheel. Mine is feared so that a 26" tire will go about 25mph. I never did mount mine (ashamed I am) so you are welcome to make me an offer on this setup. Pm me for pics. For simplicity sake, it doesn't need to slide, but if I were going that route I would try to get a bike with both rear brake bosses for cantilevers and disc mount capability. This way I could mount the outrunner on the brakes bosses and have disc rear brake. It really is a simple solution to the gearing issues, and very lightweight at the same time.
wiredsim said:Sorry to bring this thread back up again for this question, but I didn't want to make a whole new thread just for this. Would it be possible to use a outrunner directly against the tire? Maybe my noob is showing but my inspiration was a picture from John in CR's thread:
Just imagine the motor a little closer to the wheel and directly pressing against the wheel. I can think if a couple of easy mounting methods that would allow you to have it pivot with cable control.
If needed one could put some friction enhancing material on the outside of the casing also.
Am I smoking something or is this feasible at all? I know friction drives aren't the most sexy of designs, but it would be dirt cheap..
That does sound like it'd be possible, but I'd be sure to find an outrunner with a supported can (Like the skirt bearing on a few of the turnigy outrunners) with something like a skirt bearing. I would think a friction enhancing material would be essential because my outrunner's surface is very smooth.
etard
100 kW
Damn, the motor IS the roller!! I never even thought of that. Genius!! But you would definately want a motor with a much thicker can than they come with currently. I can see the outside flexing with pressure from the tire, and then there is the possibility of random debris striking it and knocking a magnet loose which would be catastrophic. Although a brush guard installed before the motor might help with this. Try it, i would be interested to see how this works.
I agree, friction drive can be sexy!
As for using a motor as the roller, it's a great idea but it would be a VERY big diameter roller. The motor would need to be super powerful to start from a stop. It would have a high top speed though!
Btw, my setup is still going strong. The magnets are still holding and I've got a big time ev grin. Cheap doesn't get any better than this. lol
As for using a motor as the roller, it's a great idea but it would be a VERY big diameter roller. The motor would need to be super powerful to start from a stop. It would have a high top speed though!
Btw, my setup is still going strong. The magnets are still holding and I've got a big time ev grin. Cheap doesn't get any better than this. lol
Grinhill
10 kW
As an example, if you used a Hobbycity 63-74 170Kv motor, this would give you a ratio of about 10.4 against a mountain bike wheel. Running this at 37V would give you a theoretical top speed of about 72km/h (45 mph).
I agree, it would be slightly overgeared. Would need bearing support at both ends of the shaft to work well.
A slice from an old innertube stretched over the can may work to improve friction (standard type, not thornproof).
I agree, it would be slightly overgeared. Would need bearing support at both ends of the shaft to work well.
A slice from an old innertube stretched over the can may work to improve friction (standard type, not thornproof).
12p3phPMDC
1 kW
- Joined
- Mar 16, 2009
- Messages
- 462
IMO, If the 63-74 Hobby City 170Kv motor has a bell support bearing on the mount side,
then it could work.
The new 80-100 180kv has a bell support bearing.
If you didn't have a bell support bearing, the cantilevered load may cause
problems and flex in the bell.
Glad to hear your setup is stll going good EVTodd.
then it could work.
The new 80-100 180kv has a bell support bearing.
If you didn't have a bell support bearing, the cantilevered load may cause
problems and flex in the bell.
Glad to hear your setup is stll going good EVTodd.
wiredsim
10 W
Thanks for the info guys, I can see where the downsides to this setup would be and I had a few thoughts to try and minimize those issues. One would be to glue/screw a metal pipe of the outside of the motor that is the length of the can. The key would be finding the right size, though the HXT 63-74 200kv looks to be just slightly smaller then 2.5". I thought about PVC but I don't think it would be wise to insulate the can. And of course make sure the magnets are glued good.
Also a 700cc wheel and tire would increase the ratio to around 11, which would give you a top speed of 37mph @ 24volt and 56mph(!) @ 36v.. The 170kv would give 31mph top speed @ 24v and 47 @ 36v. What would work best would be the Turnigy 80-100 130kv motor, but I wouldn't dare test this with a $150 motor. That would 36mph at 36volts if my math is right, and a crap-ton of torque I would bet.
The other thing would be to mount it on a slider, so that you could actually start spinning it up before it contacts the wheel. Something like this:
That would reduce starting load and also allow the motor to "bite" into the wheel as the load got higher.
Not sure if this is how I want to start with E-bikes but the price is right if it works and doesn't destroy motors. :|
Also a 700cc wheel and tire would increase the ratio to around 11, which would give you a top speed of 37mph @ 24volt and 56mph(!) @ 36v.. The 170kv would give 31mph top speed @ 24v and 47 @ 36v. What would work best would be the Turnigy 80-100 130kv motor, but I wouldn't dare test this with a $150 motor. That would 36mph at 36volts if my math is right, and a crap-ton of torque I would bet.
The other thing would be to mount it on a slider, so that you could actually start spinning it up before it contacts the wheel. Something like this:
That would reduce starting load and also allow the motor to "bite" into the wheel as the load got higher.
Not sure if this is how I want to start with E-bikes but the price is right if it works and doesn't destroy motors. :|
jmygann
100 kW
- Joined
- May 30, 2008
- Messages
- 1,069
so which RC motor would work best on a 24 in wheel/tire assuming a direct friction drive to the tire ?
would a freewheel be of any advantage ?
How narrow could the roller be to keep the ratio as great as possible ?
http://vodpod.com/watch/2126019-homemade-friction-drive-electric-bicycle
would a freewheel be of any advantage ?
How narrow could the roller be to keep the ratio as great as possible ?
http://vodpod.com/watch/2126019-homemade-friction-drive-electric-bicycle
Kepler
10 MW
Great thread guys. My first post on this forum so be gentle with me. I am a long time electric RC Heli flier and a keen rider so to end up here was just a matter of time. I really like the friction drive arrangement especially for a bike that you still want to use as a normal bike.
My small addition to this discussion is the possibility of using a high power servo with a cam arrangement on it push the drive unit into the tire and back it off as you take off power to a point whereby the drive completely losses contact with the tire when the throttle is released. Hobby City has some seriously powerful servos that could easily apply enough pressure to a spring loaded pivoting mechanism. Control would be through a simple Ve-tail mixer and could be setup to provide variable pressure onto the tire depending on the throttle position.
This would negate the need for a one way bearings in the roller and make the system electronically tunable.
I would use this servo https://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8496
And a Ve-tail mixer something like this http://www.desertrc.com/ (still need a bit more research on this one)
My apologies if I am just going over an old idea here but I thought it worth a mention.
My small addition to this discussion is the possibility of using a high power servo with a cam arrangement on it push the drive unit into the tire and back it off as you take off power to a point whereby the drive completely losses contact with the tire when the throttle is released. Hobby City has some seriously powerful servos that could easily apply enough pressure to a spring loaded pivoting mechanism. Control would be through a simple Ve-tail mixer and could be setup to provide variable pressure onto the tire depending on the throttle position.
This would negate the need for a one way bearings in the roller and make the system electronically tunable.
I would use this servo https://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8496
And a Ve-tail mixer something like this http://www.desertrc.com/ (still need a bit more research on this one)
My apologies if I am just going over an old idea here but I thought it worth a mention.
etard
100 kW
Finally!!! I've always thought the addition of servos for changing gears, applying rollers, heck even suspension adjustments could be added to the rc driven bikes to automate controls. Yes, it is another system to go wrong or fix or get wet, but with all the knowledge here, it should not be too difficult to apply. Maybe I am getting the cart before the horse though, and EVTodd's design is ingenious in how it works mechanically with zero maintanence etc... Welcome to the forum Kepler, don't be shy on posting whatever you feel, but please do a basic search to see if it has been brought up before.
I am going back to this roller design, I am attracted to it's simplicity. Here is my latest incarnation. I bought a pair of skis (picture hot pink and neon yellow and green from the 80's) I am going to mount everything on the ski, batteries, controller, and roller. I will drill a hole in the ski and devise a pivot on the seatpost where half is behind over the back wheel and half is resting on the top tube of the bike. I will have a knob for adjustment (or servo :wink: ) which will raise or lower the front putting pressure on the tire that can be adjusted on the go by the rider, or lifted off the tire completely. The whole system can be takes off in less than 15 seconds and only the throttle will remain on the bike.
Thoughts? Is the ski necesary? I have actually thought of using two golf club shafts for this and mounting the battery in a backpack to keep the handling of the bike more stock. Can anybody think of improvements before I hack up these $5 skis?
Also, I want to trial run this on a hardtail and eventually apply it to a rear suspension bike, making a strut from the rear axle that moves the ski at the same rate as the suspension. Now I know the ski will act similar to the leaf spring in a car, but if I dial the suspension down how will the ski effect rebound etc...?
I've always thought the addition of servos for changing gears, applying rollers, heck even suspension adjustments could be added to the rc driven bikes to automate controls. Yes, it is another system to go wrong or fix or get wet, but with all the knowledge here, it should not be too difficult to apply. Maybe I am getting the cart before the horse though, and EVTodd's design is ingenious in how it works mechanically with zero maintanence etc... Welcome to the forum Kepler, don't be shy on posting whatever you feel, but please do a basic search to see if it has been brought up before.I am going back to this roller design, I am attracted to it's simplicity. Here is my latest incarnation. I bought a pair of skis (picture hot pink and neon yellow and green from the 80's) I am going to mount everything on the ski, batteries, controller, and roller. I will drill a hole in the ski and devise a pivot on the seatpost where half is behind over the back wheel and half is resting on the top tube of the bike. I will have a knob for adjustment (or servo :wink: ) which will raise or lower the front putting pressure on the tire that can be adjusted on the go by the rider, or lifted off the tire completely. The whole system can be takes off in less than 15 seconds and only the throttle will remain on the bike.
Thoughts? Is the ski necesary? I have actually thought of using two golf club shafts for this and mounting the battery in a backpack to keep the handling of the bike more stock. Can anybody think of improvements before I hack up these $5 skis?
Also, I want to trial run this on a hardtail and eventually apply it to a rear suspension bike, making a strut from the rear axle that moves the ski at the same rate as the suspension. Now I know the ski will act similar to the leaf spring in a car, but if I dial the suspension down how will the ski effect rebound etc...?
Also a first poster here...
I will be building a brushless powered bike this winter using a friction drive. The simplicity of the build appeals to me, as this will be my first e-bike project. While my first prototype will be a single friction drive just so I have some base in building these types of things, I had a thought about providing two gear ratios as a follow-up project.
Why can't a triangular assembly be built so that the motor can be mounted near to top, its drive shaft fitted with a belt pulley (or sprocket). Have the belt (or chain) turn two drive wheels of differing diameters mounted on the bottom of the assembly near the bike's rear wheel. Have this entire assembly rotate on an axes near the center with a spring forced return. To get into second, engage the larger drive wheel by rotating the entire assembly so that the smaller wheel lifts from the bike's rear wheel and the larger one engages. There could be some cable shifter assembly running to the handlebars so the throttle is selected from that area. Lock the lever by whatever method you choose to resist the spring force return... doesn't really matter what's done to accomplish this part. Anyway, both drive wheels would be spinning regardless of which one is engages obviously, and there would be more friction losses in the assembly, but that's okay as long as I can get two gearing ratios out of this. I'm really just wondering if any of you think the above drive assembly would work.
Does anyone even understand what I mean? I wonder if I should just draw it and post a picture, 'cause it's awful hard to describe in text.
I will be building a brushless powered bike this winter using a friction drive. The simplicity of the build appeals to me, as this will be my first e-bike project. While my first prototype will be a single friction drive just so I have some base in building these types of things, I had a thought about providing two gear ratios as a follow-up project.
Why can't a triangular assembly be built so that the motor can be mounted near to top, its drive shaft fitted with a belt pulley (or sprocket). Have the belt (or chain) turn two drive wheels of differing diameters mounted on the bottom of the assembly near the bike's rear wheel. Have this entire assembly rotate on an axes near the center with a spring forced return. To get into second, engage the larger drive wheel by rotating the entire assembly so that the smaller wheel lifts from the bike's rear wheel and the larger one engages. There could be some cable shifter assembly running to the handlebars so the throttle is selected from that area. Lock the lever by whatever method you choose to resist the spring force return... doesn't really matter what's done to accomplish this part. Anyway, both drive wheels would be spinning regardless of which one is engages obviously, and there would be more friction losses in the assembly, but that's okay as long as I can get two gearing ratios out of this. I'm really just wondering if any of you think the above drive assembly would work.
Does anyone even understand what I mean? I wonder if I should just draw it and post a picture, 'cause it's awful hard to describe in text.
Grinhill
10 kW
I get it. Sounds feasible to me.
spinningmagnets
100 TW
New RC/friction-drive just posted:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=14403&start=0
http://endless-sphere.com/forums/viewtopic.php?f=28&t=14403&start=0
Kepler
10 MW
Any updates on this fine friction setup? How has it been holding up?
Kepler said:
Kepler,
I didn't ride my bike a whole lot after November but the drive held up great with some pretty regular hard use. My biggest concern was with the magnets coming loose but with the epoxy I added it never happened (knock on wood).
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