Friction drive outrunner setup. New DJ bike.

[EVTodd]

Not sure if I talked about it much more but I did contact shops about having rollers hardened. Most places don't even want to talk to you unless you're doing big quantities (100+ at a time). Well, actually, they'll do less but charge the same.

Again, my big issue is that I'm just not sure there's enough interest. I plan on making a batch of 20 rollers but I'm not so sure even that many will sell.

 

[etard]

I think this would be the sort of business that would only thrive in small circles as a boutique business on the side. A college campus would be great for this. Except, you have to park your bike and leave it alot, so something removable and compact would be ideal. It's gonna be hard to beat Keplers drive for this. So rather than redesigning the wheel, why not just sell his as a complete drive? You could even pretty it up a bit more for the fixie guys. :wink:

On the ev warrior roller, I am wondering if we could track down the original fabricator of these and see if they can't fo another production run. I wonder how hard it would be to find an ex employee of the company, I bet they could explain how and where these came from.

Spin, I like your idea of different rollers, but I think there must be one size that will suffice and the only people who will want to go through the process of changing these out are racers. At that point I can't see much of a market... yet.

I'm not trying to be Debbie Downer here, just calling it how I see it. It's only my opinion. I too, would love to get a detachable, lightweight, low speed drive going that I could sell to the DH MTB guys ad a shuttle, it's just nearly impossible to adapt to so many rear suspension designs. A copy of the Shuttle Buddy only electric is the best way to go as I see it.

 

[spinningmagnets]

There is no doubt in my mind that I could sell many of your complete drive units to local college students. Of course, my personal enthusiasm is no guarantee. If you want to cautiously dip your toe in the water (rather than plunge in), I will buy 2 of the rollers you make. I can make two of the drives (or I can pay you to make two of them, your choice). One to display for test-rides and one-in-hand to sell.

Big-Poppi Bicycles nearby is interested, but they need a test-drive and may only sell on commission at first. Or, I can make them, sell them myself direct to customers, and send you a royalty per unit. The rollers are the sticking point. If you will make 20 (they absolutely must be hardened), thats a good start.

I can make the drive, but the rollers would have to be made by a machinist, and theres no sense me ordering a batch from here, when you'll be making some (your batches can be larger, rather than you and I both ordering small batches)

They must be priced high enough so that if more orders come in, it is worth your while to make more. At that point its up to the customers to decide if a $40 roller (that "might" wear out in a year) is worthwhile. Personally, I feel spending $40 a year for a new roller is a tremendous bargain for what your kit provides, but cash-holding customers can be fickle....

What price makes it worth your time to make a batch of these rollers? $10 one-way bearing, bronze greased bushing, steel tube thats been bored to fit, knurled, and hardened...

 

[spinningmagnets]

etard, I don't really see Todds drive and Keplers as being in competition. Kepler uses Lipo, an ESC, and the RC-outrunner shell as the friction roller. It is quite simply the lightest and most compact friction-drive possible. It appeals to an upscale market and will be priced accordingly.

The performance of Todds drive seems to be roughly equal on paper (that is, they're both very good). That being said, although Todds drive is very compact and light, it is bulkier and heavier than Keplers. However, it is light enough to still be very desirable to the customers I'd like to target,...and it will cost much less.

Someone might suggest to substitute LiPo on Todds drive to make it smaller and lighter, but I actually believe using 36V cordless drill batteries will appeal to college students (and also "average Joes"). A quick scan of websites concerning LiPo will turn up many cautions about battery fires, and many potential customers would not call back to tell you why they didn't buy the drive.

The majority of potential customers are not technical enthusiasts. They want a product like a microwave oven. You plug it in and it just works. Todd has already designed it, and I don't see any way to improve it (other than my interest in experimental removable sleeves, which I can't help but to ponder, but it appears the idea is not likely to bear fruit)

 

[EVTodd]

I honestly don't see my drive and Kepler's in competition either. The only real similarity is that they're both friction drive. Performance wise with everything being equal (motor/batteries) they should be the same but I have to say that I would put my drive up against any other friction drive out there. I personally think the sliding mount with a roller already on the tire is the way to go. It's smooth and simply works great. I also think smaller diameter rollers make a friction drive a lot more enjoyable.

A few numbers to give you an idea of the actual size of my drive. It weighs 3 pounds (that includes the motor) and measures 6" by 3" by 2.25". That's the motor with the drive assembly and roller. Keep in mind that those number are from the first drive I made. The ones I'm working on now only have 14 total parts (only 4 machined parts if you exclude the hardware) and will have a slightly smaller width. Of course, my drive doesn't have a mount already on it. You have to use a rack or your own method of attaching. Again, a nice feature of Kepler's drive is that it has the attachment method built in. I guess it depends on what you want. I love mounting to a rack since I can use panniers with it and well, a rack is always useful.

I think the big thing is that my first drive wasn't pretty. lol I honestly made it for myself and really didn't even have plans to show it to anyone at the time.

One of my things right now is not wanting to step on Kepler's project. I totally agree that friction drive probably won't be a big market. Maybe I'm wrong. It's a big world.

I'm still toying with the idea of making individual parts available for people that want to put their own drives together.

The roller isn't a big issue either. I'm sure Ev Warrior just had a machine shop make them. No big deal for me to make them but I would love to come up with one that didn't need to be hardened or have the bearing pressed in. I have 20 hardened shafts sitting in my shop. I'm working on it.

 

[etard]

This is what I'm talking about fellas! I'm glad we that all have different views on what we want to accomplish and how to get there. Spin, you have a knack for the technical contemplation of these things. And Todd, you are an amazing builder, I believe that your drive would beat Keplers head to head. I want to fill a nitch that frankly, i'm suprised hasn't been done yet. I believe I can design and build a drive similar to this, but without that bulky thing coming off the side. :wink:

P.S. Todd, I hope you don't mind us bantering away like this in your thread, you might have to start another one when you get your drive finished.

 

[Thud]

CHIME!
Todd-yes soldering up the shunt will get amp rating up, not sure if it would be a big deal or not in this application. if you run into throtle cutting out issues we have a work around for that also.
(I know I am pushing my 18fet units too hard when i get the throttle cut-out under accelration...a work in progress)

About the 6 fet controllers, I really like the 1 resurected. it spins a 63-54-250kv tunigy with conviction & doesn't get warm (modded with 4110fets) Lyen sells these already modded for a few dollars more than the E-crazymans units. I will say that I have yet to match the "punch in the eye" acceleration I can achive with my HV160. but I am totaly amazed at the starting tourque of a tiny sensored motor.

About friction drives: I just finished a cyclone based unit for a friend & really tried to convince him to try a friction drive....I love the size of these units you guys have built & how adapable they are to a wide cross section of frames. It Just looks to be a really cost effective assist method. someday I will have to try one......some day.

 

[EVTodd]

P.S. Todd, I hope you don't mind us bantering away like this in your thread, you might have to start another one when you get your drive finished.

Naw, I don't mind. I'll start another thread with my builds when I get my girlfriend's bike done.

I've always thought the shuttle buddy was cool. I wonder if it freewheels. Probably not since it's only intended purpose is to get you to the top of a mountain.

One thing I found funny in their video was watching people use the drive to get to the top and then pulling it off and sticking it in a backpack right away. Wouldn't the motor be too hot to do it that quick?

 

[etard]

I met the guys the built it at a local mt bike race, they do all the work themselves. It's really a neat product, the only thing is, it's loud and gassy. Two things that are a total turn off to ALOT of the mt bike community. Can you blame them!!?? It really polarizes people like no other on the local my bike forum. I have even asked to buy the drive spindle, "no way, not unless you have bought the whole system!"

Speaking of drive spindles ( what else would we be talking about :lol: ) if you do a search of scooter spindle or drive spindle a bunch of these rollers pop up in different sizes, I wonder if one doesn't have an inner dimension close to what we need to fit the one way bearing into. Even if you had to take a little off, these are already gnurled and ready to go. Sorry, I can't link from my phone, eBay always sends me to the mobile site which sucks.

 

[spinningmagnets]

If I make a drive for myself (edit: aug 12th, "not for sale to the public") I would start with a solid roller (hardened steel) from BMP. They are $20 plus tax and shipping, and they seem to have no shortage of supply. It takes a 1/2" shaft. Although I'd use the one-way bearing on the side (rather than inside the roller), so, the shaft end would still have to be hardened for the one-way bearing-rollers to work.

I think I might experiment with making a few odd-shaped rollers (just for fun), and by having the one-way bearing on a separate part of the shaft, it makes that type of experimentation easier, but the BMP roller is a decent start. (the $6 polyurethane boat-trailer roller above has a 1/2" bore, though it is unlikely to last long. Hard 2-1/2" wide skateboards wheels slid over a 22mm bushing perhaps?)

Just recieved roller from BMP, its 3-1/4" long...

 

[EVTodd]

If I make a drive for myself, I would start with a solid roller (hardened steel) from BMP. They are $20 plus tax and shipping, and they seem to have no shortage of supply. It takes a 1/2" shaft. Although I'd use the one-way bearing on the side (rather than inside the roller), so, the shaft end would still have to be hardened for the one-way bearing-rollers to work.

I think I might experiment with making a few odd-shaped rollers (just for fun), and by having the one-way bearing on a separate part of the shaft, it makes that type of experimentation easier, but the BMP roller is a decent start. (the $6 polyurethane boat-trailer roller above has a 1/2" bore, though it is unlikely to last long. Hard 2-1/2" wide skateboards wheels slid over a 22mm bushing perhaps?)

How would you have the clutch bearing off to the side? The roller would still have to spin on the shaft and the bearing would have to be attached to the roller somehow.

I know a couple of people have talked about doing the same thing. For some reason I can't picture how that would work.

 

[spinningmagnets]

The shaft and solid roller (grub-screwed together) would both be "live" and always spinning with the tire. The one-way bearing would slip-fit inside the center of a 5mm-HTD pulley (slid onto on the right side of the drive?). This type of pulley is available in a couple dozen different tooth-counts from 2" diameter up to 4-1/2" diameter with a metal center that has a 0.750" ID. Some other projects have suggested that loctite may be strong enough to hold these together on a medium-power set-up.

Should be a cheap experiment...since the one-way freewheeling bearing would be separate from the roller, I could even JB-epoxy/Devcon them together. Grin had some toothed-belt slippage at higher powers, but he was driving a large diameter Left-Side-Drive pulley (24"?) and the motor pulley was only a tiny 22-tooth. I'm likely to use something around a 40-tooth, and it will be driving a 1"-2" diameter roller.

edit: BMP's gasoline friction-Drive kit can use a solid roller (no freewheel) because they have a disengagement lever to lift the roller off of the tire when pedaling...They stock 1" and 1-1/4" diameters.

Edit: #2 Heres a pic of Bubbas build 3 where he put a freewheel inside an aluminum HTD pulley he bored out. Just imagine that the shaft on which the freewheeling pulley is attached (on the left), will be the live-shaft/roller combo. I imagine I will use a smaller shaft pulley and a larger motor pulley than Bubba (3:2 ratio?), though the motor pulley will still be the smaller of the two.

Matt did something similar a while back...but I'm going to blame Bubba for making me lose sleep thinking about this one...

 

[EVTodd]

Ya just lost me. So, you're planning on a reduction as an easier way to mount a clutch bearing for a freewheeling roller?

If I'm not misunderstanding (and correct me if I am) then you're over thinking this WAY too much!

Seriously, I think we've pretty much exhausting a subject (the drive roller) that really isn't complicated at all.

I hope I'm not sounding like a jerk but I've said it over and over and over. Friction drive is all about simplicity.

For experimenting why not just make an aluminum roller with a clutch bearing in it that you can put adhesive backed grip tape on? Isn't that what Kepler's drive uses on the outrunner can?

I could have a few of those ready within a week or so.

 

[spinningmagnets]

HA! yes I probably AM overthinking it. I don't intend to sell what I was discussing the last few posts, its just an odd-roller road-test rig. I can easily make a dozen different shapes of roller with a 1/2" bore and quickly have them on the road.

As I said before, your design is well-done and complete, and that is the design I could sell.

On that note, I am not in a hurry, but I could pay you now for two of the rollers you mentioned you'd be making. To help with the up-front costs.

 

[EVTodd]

HA! yes I probably AM overthinking it. I don't intend to sell what I was discussing the last few posts, its just an odd-roller road-test rig. As I said before, your design is well-done and complete, and that is the design I could sell.

On that note, I am not in a hurry, but I could pay you now for two of the rollers you mentioned you'd be making. To help with the up-front costs.

Hold off on the payment. I'll go ahead and order a few clutch bearings and get a couple rollers made up. I'm actually curious to see how well grip tape would hold up on one.

Shouldn't take more than a week to get them done. I just hate taking money for items I don't have in hand yet.

 

[Solcar]

Friction drive is all about simplicity.

For experimenting why not just make an aluminum roller with a clutch bearing in it that you can put adhesive backed grip tape on? Isn't that what Kepler's drive uses on the outrunner can?

I left that previous comment because simplicity hopefully will become a more revered a concept in the world soon. That friction tape is what I needed to know of since I have to try to build a custom drive using a rear wheel hub and didn't know what to do to the hub steel to protect it.

Edit: I had friction on my mind. The term "grip tape" might have an important distinction from "friction tape" other than that it is used on skate boards. I remember years ago referring to friction tape wrapped around the handle of a baseball bat. I meant "grip" instead of "friction."

 

[EVTodd]

Friction drive is all about simplicity.

For experimenting why not just make an aluminum roller with a clutch bearing in it that you can put adhesive backed grip tape on? Isn't that what Kepler's drive uses on the outrunner can?

I left that previous comment because simplicity hopefully will become a more revered a concept in the world soon. That friction tape is what I needed to know of since I have to try to build a custom drive using a rear wheel hub and didn't know what to do to the hub steel to protect it.

Edit: I had friction on my mind. The term "grip tape" might have an important distinction from "friction tape" other than that it is used on skate boards. I remember years ago referring to friction tape wrapped around the handle of a baseball bat. I meant "grip" instead of "friction."

Yup, grip tape like skateboards use is what I was thinking of. They sell the same stuff to stick to steps to make them non-slip too.

Not sure what that is called. Tread tape?

Just did a quick search. Looks like most places call it non-slip tape.

Maybe we can get Kepler to chime in here. Like I said, I think that's what he's using on his motors. Is it holding up?

 

[mani9876]

This is the tape what Kepler used:
http://www.hardwareandtools.com/3M-7639-Anti-Slip-Step-and-Ladder-Tread-Strip-Heavy-Duty-Black-2-By-9-Inch-u234846.html

ATB

 

[Solcar]

Thanks mani9876 and Todd, that's another design hurdle cleared.

 

[EVTodd]

I finally got everything together on the DJ bike. I really like this new frame. Very comfortable. I should have switched to a more upright bike a long time ago.

Now 30 mph actually feels kind of slow. It's amazing how switching bikes can make that big of a difference. My next project is going to be a DH bike. If anyone knows of one for sale cheap please pm me.

 

[EVTodd]

I finally got some time to get a couple of mounts going on the mill. Snapped a picture for the hell of it:

 

[mani9876]

That's a CNC mill isn't it ?

 

[EVTodd]

That's a CNC mill isn't it ?

Yup, that's my smaller desktop cnc mill making the hole for the bearings that are pressed in. I'm always amazed that these little machines can be accurate enough to keep tolerances that tight.

 

[etard]

What's a desktop CNC mill? Is it like this:

Cuz, I just picked me up one. No, CNC here baby!

How are you coming on your drives Todd? Are you still planning on producing a couple?

 

[EVTodd]

What's a desktop CNC mill? Is it like this:

Cuz, I just picked me up one. No, CNC here baby!

How are you coming on your drives Todd? Are you still planning on producing a couple?

Nice Rusnok mill. You need to convert it to cnc!

The one in my photo is a highly modified MaxNC 15. Just like friction drive a lot of people talk crap about MaxNC but I've had great luck with them. I'm a firm believer that if you're making small parts a small machine (set up correctly) is fine. I currently have 2 small cnc mills, a larger Chinese mill, 2 cnc lathes, and a manual Chinese lathe. Fun stuff!

As for making a couple of drives... I have 3 sitting in front of me right now. One is my girlfriend's and I'm going to make one little change to the other two. Not quite sure what I'm doing with them yet. lol