Friction drive outrunner setup. New DJ bike.

FD seems to be the bastard child in ebikes. This video posted earlier http://endless-sphere.com/forums/viewtopic.php?f=28&t=9652&start=325#p427607
really impressed me with its performance in grabbing and releasing the tire. With the flat tire and the spindle grabbing the full width it seems there would be any slippage.

I also saw spinningmagnets built one based on this sliding design rather than the swinging design.

Does anyone know if EVTodd or Spinningmagnets shared their design specs?

Does anyone know if EVTodd or Spinningmagnets shared their design specs?

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Check the build link in my sig, I documented how to make the one I have. I tried to show methods that allowed any garage builder to make one with only a hacksaw, drill, and a vice. Best of luck...

SM,
Thanks for the reply. I did view your link, just went forward rather than start back at the beginning. Will review and post on that thread. The sliding channel design really looks solid and does well at engaging and releasing from stops and while underway. Thanks

Quick update. Just started riding this year. Everything still going strong. Still on the original TowerPro motor with original bearings, will it make it another season? :lol:

I put a new back tire on this year just because the last one was getting old. It did, however, have plenty of tread left and I'm keeping it around as a spare.

I ended up needing new bearings in my rear hub. Kinda funny that they gave out before the bearings in the motor. That made me chuckle a little after all the comments about how the bearings in this motor wouldn't last 5 minutes. Obviously having the roller shaft supported by bearings on both sides helps a bit.

It really is too bad so many people refuse to believe friction drive can work so well. I wish those people could try this bike.

Read through every page xD
Amazing work you guys have done, hard to believe this threads been around since 2011
I've recently put together my own friction drive on a "fixie" and lets just say ive been obsessed since i felt that first pedal free ride.

Right now I've just got my outrunner coated in anti-slip tape, and anchored in place on the wheel, but I've got a real question after seeing so much obsession with the motor swing/disengagement. Is the purpose of the variable tire engagement for purely efficiency standpoints?

I can understand that any contact between the motor and the wheel deforms the wheel; but could it possibly damage the motor? I commute about 4.5miles to and from work, on an EXTREMELY flat and smooth surface; i dont need to or want to go over 25mph. I have a turningy sk 63--(something)192kv, and right now im running it on a 4S 160000mah 10C battery with a 60amp esc to keep things cool. I've been VERY conservative with how i ride because im still in gradschool and paying for replacement parts is not really an option.

Sorry, rambling.... the question is: Does having the outrunner motor applied directly to the wheel AT ALL TIMES damage the motor in anyway? I know its more efficient to pedal with the motor/rotor disengaged, but I seriously do not have the time or $$$ to machine a swinging or sliding mechanism. Am i going to burn out my motor by having it rotate freely with the wheel without applying power?

Any advice or experience with non-sliding, constant contact outrunner friction drives would be appreciated. Oh, and much respect to everyone who posted in the thread. We're all standing on the shoulders of giants.

welcome aboard.

If you have no other option then just do it. Just make sure you have the motor pressed onto the tire so there is no slippage. At worst case, you are out a motor but in this game this cost is not much of the total bill.

I don't have personal real world experience with FD drive but I doubt the motor will suffer any damage. It depends on how hard the motor is pressed against the wheel and the wear that would put on the bearings. Reasons for having the swing arm is so the motor can grab into the wheel a lot more than you will keep applied 100% of the time. If you do have it mounted with a lot of force, you may suffer premature wear. The other reason is while coasting you get relief from the motor noise.

ActionJ4ckson said:

Am i going to burn out my motor by having it rotate freely with the wheel without applying power?

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No.

amberwolf said:

ActionJ4ckson said:

Am i going to burn out my motor by having it rotate freely with the wheel without applying power?

Click to expand...

No.

Click to expand...

It won't hurt the motor but some rc controllers don't like it. At least that's what people say. I've used my friction drive for long periods of time with the motor spilling all the time and it never hurt my Castle HV85.

WOW thanks for the incredibly quick response guys. I am just now checking out the responses because I was honestly expecting the thread to be dead for a few weeks, good to see everyone's still active!

I will post a picture of my bike later today, it is nothing impressive, but a picture is worth 1000 words.

I have since last posting purchased a new motor because I thought my first was broken. As it turns out, there is this thing called "FET drag" that can make the motor hard to spin when it is disconnected from the battery but not the ESC.

I was out for a ride the other night and ran the battery below 3.6v, so I unplugged it BUT NOT THE ESC. I noticed the bike was rather difficult to ride, but I was in a questionable neighborhood at 2:00am in the morning, so needless to say, I peddled through any resistance that i felt in the motor all while my ESC made all sorts of beeping noises I've never heard before XD When I got back home and recharged my battery nothing was working as expected, so i figured the motor and ESC were trash.

To anyone out there who may have experienced the same thing I have, if you motor is in constant contact with the wheel; make sure you either:
1) have both the battery and the ESC plugged in
2) disconnect both - the battery AND the esc

Otherwise what will happen is the ESC will slowly start discharging it's capacitors, making the motor and the wheel almost impossible to turn freely. If you push through, and continuously rotate the motor, you will damage and potentially break the ESC (and maybe even the motor?). Unplug both when you are not using them if you do not use swing/hinged engagement.

Finally got a new ESC that supports freewheel.

Few days late but here it is. Going to up the 4s battery to a 12 someday lol

When using a skinny tire, a friction drive might be limited to around 750W, and above that it may likely experience slippage. You can try out more voltage to see how it works out for you, I just wanted you to be aware of a likely issue.

I Took EVTodd's suggestion and went to a fat cruiser tire with a squared-off tread (which doubled the roller-to-tread contact), and I was able to reliably use around 1000W. Mine seemed to work well on flat land at 22V (6S), but when I was going on hills, there was a big improvement when I went to 10S (36V)