I'm thinking about converting from gas to elect

[bigkahuna]

Hi all,

I'm seriously thinking about converting my bike to electric powered. I added a gas powered friction drive a few weeks ago and am not happy with it. The biggest reason (and I wish I had thought of this before buying the kit) is that I can no longer ride on bike paths, which is something I really enjoy doing. There are other reasons, but that's the biggest. So I'm thinking about going electric instead (in my state bikes with motors less than 750 W are considered bicycles). I'm sold on friction drives and am thinking about a DIY friction drive like what some of the folks here have built. I've got limited machining abilities (drill press and table saw is it) but am handy with wood and fiberglass. Here's a pic of my bike sans gas drive:

 

[nuevomexicano]

I'm interested in knowing why you're sold on friction drives? I'm not trying to talk you out of one, but want to know what I'm missing in your opinion.

My bother rode a gas powered, friction drive bicycle across 2/3 of the US a few years back. It had a certain simplicity in some respects (easy to engage/disengage, no extra drive system needed) and was inefficient in others (drive wear, etc...). His experience was one reason I went with a geared hub motor--the freewheel makes up for the ease of engaging/disengaging-- when I went electric.

 

[bigkahuna]

Simplicity is the main reason I find them so attractive. I've got an aluminum framed cruiser with 48 spoke, 29" wheels, so it wouldn't be an easy fit with those cheap chinese in frame chain drive kits. So I broke the bank and I bought a Staton friction drive with a Subaru 4 stroke engine. Nice kite and well thought out, it took just a few hours to get everything together. Worked great, but I miss being able to ride on bike trails and I don't like the noise (although 4 strokes aren't as bad as 2 strokes). I saw a couple build threads here where people used a large brushless outrunner motor, glued a sanding belt to it, and mounted it to the frame. Doesn't get any simpler than that IMO. Would love to build something like that for my bike, and I will, just as soon as I sell my gas powered friction drive.

 

[icecube57]

When you look at cost its easier to install a geared hub for the same performance. DD adds weight but has the ability to take more power. With cell mans hub ur looking at 150 plus shipping and the cost of batteries. You would have a reduced range going electric vs gas

 

[bigkahuna]

Thanks, I'm aware of the reduced range and also the loss in power vs. a direct drive. I considered that when I was looking at ICE drives but decided is wasn't an issue for me since I enjoy pedaling. My main interest is assistance in getting over one hill. Love the idea of buying some parts from HobbyKing, gluing a sanding belt to the outrunner, making a mount, and go! Just seems like an easy way to go. Could you give me a link to the hub you mentioned? I'm not familiar with that one. My bike has a Shimano clone rear hub and 29" 48 spoke wheels, which makes doing anything mechanical more complicated.

 

[FMB42]

Hey bigkahuna, that bike of yours looks to be a Genesis "Onyx(?) cruiser.

If so, those bikes, IIRC, have an aluminum frame and, as such, care must be taken when selecting and installing a hub motor (aluminum isn't the best material if, you need to "stretch the dropouts" in order to fit the motor) . I'm not sure what the fork is made of but, if it's steel, you may want to consider a front wheel drive hub motor (if you decide to go that route).

 

[nuevomexicano]

Simplicity is the main reason I find them so attractive. I've got an aluminum framed cruiser with 48 spoke, 29" wheels, so it wouldn't be an easy fit with those cheap chinese in frame chain drive kits. So I broke the bank and I bought a Staton friction drive with a Subaru 4 stroke engine. Nice kite and well thought out, it took just a few hours to get everything together. Worked great, but I miss being able to ride on bike trails and I don't like the noise (although 4 strokes aren't as bad as 2 strokes). I saw a couple build threads here where people used a large brushless outrunner motor, glued a sanding belt to it, and mounted it to the frame. Doesn't get any simpler than that IMO. Would love to build something like that for my bike, and I will, just as soon as I sell my gas powered friction drive.

I guess I still find the geared hub motor to be even simpler. And its not hard to get a hub motor mounted on a 29inch wheel.

My brother also used a Subaru engine when he did his long trip. At some point he noticed the top speed decreasing. He did some rough math and determined that it was in line with the same decreasing percentage of his bicycle tire and the friction wheel diameter

I definitely share your sentiment about noise. I'm finding myself riding my scooter less and less since I got the electric bicycle (and its even a good 4 stroke Honda 50cc). Every time I ride the scooter I immediately notice the noise above all else.

 

[wineboyrider]

Another plus to a geared hub motor is that the smaller ones are very stealthy and relatively quiet. I think a geared hub motor would be a much nicer setup than any friction drive IMHO. 8)

 

[MikeFairbanks]

What can you tell us about friction drives in terms of offroading?

Here's my thing: I just ordered another electric kit for my bike (I installed one on a trike a while back) and love electric power. Like you, I have bike paths and need electric. It takes me about 20 minutes to get to work by bike path using an electric hub motor.

And I'm sticking with that plan.

BUT, I'd also like to build something gas because I have a cheap Schwinn ranger and also a dirt shortcut to work that I could easily turn into a ten-minute commute, but there's no way I'd take a decent bike on those trails. I went down there today exploring, and some of the paths are horrendous.

But it would be fun to take a beater bike out there. Ideally I'd pick up a dirt bike.

Check this out:

On my paved ride to work, it's 4.0 miles, and there are three significant hills to slow me down (motor or not).

The dirt road is mostly level, 2.5 miles, with slight dips up and down (easy to coast through them due to momentum) and only one hill at the end (not a big one).


A dualsport motorcycle would be ideal. Even a Jeep could do it (if I take a chainsaw to this one fallen tree out there).

This map shows paved (red) and unpaved (yellow). My house is at the bottom of the map, and work is at the top.

 

[bigkahuna]

What can you tell us about friction drives in terms of offroading?

I think one of the limitations you might run into is that a super knobby off road tire won't work very well with the friction cylinder. That's not an issue for me as I don't really need super knobby tires. There's a video in a recent thread where the fellow is flying at 40 kph through a wooded trail using a DIY friction drive. One of the most exciting motorized bike videos I've ever seen, definitely proves it can be done.

If you want a gas powered friction drive, drop me a PM. Mine has just a few hours on it, I bought it 2 weeks ago but soon realized that what I really want is an electric drive.

 

[spinningmagnets]

Could you give me a link to the hub you mentioned?

http://www.emissions-free.com/catalog/c5_p1.html

 

[bigkahuna]

Yup, the bike is a Kent / Genesis Onyx 29er Cruiser, purchased from Walmart. The front fork is steel, but the rest of the frame is Aluminum. I spent weeks looking at different ways to set up direct drives when I was looking at ICE power but ran into numerous issues. In order to use a direct drive / geared hub I'd need to also buy a new rim (mine uses 48 spokes) and new spokes. Then I'd need to lace the new wheel (something I've not done before). Finally, I'd end up with a bike with mis-matched front and back wheels, the rims on this bike are unlike any I've ever seen before (they are 1" deep and black powder coat). When you add all this up, it's no longer an "easy or cheap" build IMO.

Yup, as long as I'm building with this bike, friction drive is the way to go IMO.

 

[dogman dan]

Which kit did you order Mike? You could get a really cheap deal on a 2812 hub from methods. Then you could ride the fun cut, which in this case is the short cut too. The motor is in a 20" hub, so you could either go bmx, or if you have a 9c motor, just swap out the stators to have a 26" dirt motor.

The other possibility is selling off the motor you just bought, and getting a 2810 motor from methods, which comes in 26" rim. Either way, that route screams for you to build a dirt bike. Very likely, you could do the ride to work and back on a 5 ah lipo pack by that route.

 

[icecube57]

Its not worth it for him to drop down to a low KV winding. At 48v that thing will choke on BEMF and be super slow.It will slow to a crawl on hills. Yeah it will never overheat but unless hes throwing some serious volts at it his peformance will suck something fierce, Plus if this is really a rough trail is it really worth trashing a bike and getting dirty before work. When ever I ride my bike i purposely find longer routes to get more ride time in.

 

[adrian_sm]

Thanks, I'm aware of the reduced range and also the loss in power vs. a direct drive.

Don't get stuck thinking the friction drive will have less power. My friction drive with a 6374-200kv motor on 5s LiPo will easily lay down 2000w, as the RC ESCs don't try to limit current at all.

Love the idea of buying some parts from HobbyKing, gluing a sanding belt to the outrunner, making a mount, and go! Just seems like an easy way to go.

I've got limited machining abilities (drill press and table saw is it) but am handy with wood and fiberglass.

Do it! Do it! Do it! It is not that hard.

I have made all my prototypes using a hacksaw or angle grinder, drill press, and table saw.
I cheated for my alpha prototypes, and got the swing arms water jet cut (but that was because I was making 30+ units, for a one off it is not necessary) and a router table just to pretty it up with some curves on the outside.

Do it! If you have the time and basic tools you could knock it up in an afternoon, or a day with stuffing around and scratching you head a bit.

- Adrian

 

[FMB42]

Have you thought about a Cyclone "non-hub motor" setup?

It might be easier to "piece together" a freewheeling chain wheel Cyclone system (w/upgraded "aftermarket" controller and battery) than going the "RC" based friction drive route.

 

[bigkahuna]

Do it! Do it! Do it! It is not that hard...

Thanks Adrian, your build was one of the ones that inspired me to give it a try. Now all I need to do is sell my almost brand new gas friction drive so I will have the money to do it.

 

[icecube57]

Unless you can buy an off the shelf system from recumpence or kelper then u better have fabrication skills. Even with the kit/system for rc and friction drive setup it will cost more money and u still have to fiddle with it to make it just right for your application.

 

[NeilP]

Just had a thought after seeing the title of this thread

If you guys in the USA called petrol 'gas" ....what do you call gas . I have a Landrover that has a gas (LPG) conversion, so it runs on both petrol and gas.

 

[bigkahuna]

Just had a thought after seeing the title of this thread

If you guys in the USA called petrol 'gas" ....what do you call gas . I have a Landrover that has a gas (LPG) conversion, so it runs on both petrol and gas.

We call petrol "gas" which is short for "gasoline". Most people call the other gas "propane" or "propane gas".

 

[NeilP]

Ahhh ok

 

[REdiculous]

We call petrol "gas" which is short for "gasoline". Most people call the other gas "propane" or "propane gas".

I've never heard someone say "propane gas" so that must be a regional thing or something. The other-other gas is "natural gas".

Calling gasoline petrol seems weird to me since petroleum can be refined into kerosene and diesel as well but they don't call those "petrol" afaik.

 

[MikeFairbanks]

Which kit did you order Mike? You could get a really cheap deal on a 2812 hub from methods. Then you could ride the fun cut, which in this case is the short cut too. The motor is in a 20" hub, so you could either go bmx, or if you have a 9c motor, just swap out the stators to have a 26" dirt motor.

The other possibility is selling off the motor you just bought, and getting a 2810 motor from methods, which comes in 26" rim. Either way, that route screams for you to build a dirt bike. Very likely, you could do the ride to work and back on a 5 ah lipo pack by that route.

I worked out a deal with Jason at EbikeKit. It's on its way.

 

[MikeFairbanks]

We (in the USA) say gas for gasoline, natural gas for natural gas, propane for liquid propane gas, and when someone farts, well, it depends.

If it's loud it's a fart. If it's quiet and short, it's a toot.

If it's silent we don't say anything.............unless it smells. Then we either call it silent but deadly, or silent and violent.

 

[spinningmagnets]

In the USA, when you buy anything labeled Propane, it must meet a standard of relatively pure C3H8. Liquid Petroleum Gas (LPG) is mostly propane, but if its labeled LPG, it can have a high percentage of burnable trash byproducts from the refinery mixed in. LPG is cheaper, but it has an ugly smelly flame.

With real propane, you can run a higher compression ratio than LPG.