Direct-drive 3220 setup with a 3-Speed Hub...

[Miles]

Gary,

It probably wouldn't be a big deal for your machinist to make #219 driver sprockets from scratch. Why don't you ask him? The advantage of using #219 is that the Extron composite sprockets (only available in that size) are a bit quieter.

 

[MitchJi]

Hi Miles,

Gary,

It probably wouldn't be a big deal for your machinist to make #219 driver sprockets from scratch. Why don't you ask him? The advantage of using #219 is that the Extron composite sprockets (only available in that size) are a bit quieter.

Would it be easier to modify the center of existing #219 sprockets rather than make sprockets from scratch?

Is it feasible to make an adaptor so that you could fasten a (possibly modified) #219 drive sprocket to a Sickbikes White FW? I realize it would have to be offset to either the inside or the outside of the White because it wouldn't fit over the shoulder.

 

[GGoodrum]

Gary, can you start from a dead stop, no peddling? If so do you have to ease into it, or can you gun it?

Sorry, I forgot to answer this earlier. It seems to be able to start fine in first gear, from a dead stop, but starting in 2nd seems to chatter just a bit. It works fine with the controller set to 24kHz, but that makes the controller run hot. I have it set now to 16kHz, which stops most of the low-speed chatter, but the ESC doesn't get hot at all.

As for gunning it, I'm sorry, but there's no way I could stay on this thing if I truly gunned it in 1st gear. If I don't let off the throttle a bit, shifting into 2nd, the front end comes up quickly. Same going into 3rd, it tries to come up, but it is controllable at least. I agree with Luke, that moving the battery up to a front-mounted basket would definitely help, but I think it would look pretty dorky.

-- Gary

 

[GGoodrum]

Gary,

It probably wouldn't be a big deal for your machinist to make #219 driver sprockets from scratch. Why don't you ask him? The advantage of using #219 is that the Extron composite sprockets (only available in that size) are a bit quieter.

You are right, of course, but I'll have to check on whether he can do hardened steel. Mitch's idea is also a good one. He did something similar several years ago, for bevel gear set I used in an electric conversion kit I did for a gas-powered RC helicopter. He drilled out and lightened a big spiral beveled gear, cut threads into it, and then made a brass adapter with a hub and setscrews, that then screwed into the gear.

 

[liveforphysics]

Same going into 3rd, it tries to come up, but it is controllable at least. I agree with Luke, that moving the battery up to a front-mounted basket would definitely help, but I think it would look pretty dorky.

-- Gary

If I recall, you are a giant Hawaiian guy, and you are riding a tiny folding bike with electronics strapped onto it that sounds like a blender and you have an I-phone zip tied on the front. Might as well embrace it and go for shooting-the-moon on the dork factor Gary.

But on a more serious note, if you can control body position, it makes a huge effect on the ability to accelerate. If you can lean down low and way out over the bars of a bike, it can do wonders for acceleration. People often say that ultra high power dirtbikes and superbikes aren't useful because they just flip over, but once you learn to throw yourself forward out over the bars as you open the throttle, it works out pretty well. Body position is a big factor.

 

[Miles]

You are right, of course, but I'll have to check on whether he can do hardened steel.

I expect he could get them case-hardened.

 

[Miles]

If I recall, you are a giant Hawaiian guy, and you are riding a tiny folding bike with electronics strapped onto it that sounds like a blender and you have an I-phone zip tied on the front. Might as well embrace it and go for shooting-the-moon on the dork factor Gary.

:lol:

 

[GGoodrum]

If I recall, you are a giant Hawaiian guy, and you are riding a tiny folding bike with electronics strapped onto it that sounds like a blender and you have an I-phone zip tied on the front. Might as well embrace it and go for shooting-the-moon on the dork factor Gary.

But on a more serious note, if you can control body position, it makes a huge effect on the ability to accelerate. If you can lean down low and way out over the bars of a bike, it can do wonders for acceleration. People often say that ultra high power dirtbikes and superbikes aren't useful because they just flip over, but once you learn to throw yourself forward out over the bars as you open the throttle, it works out pretty well. Body position is a big factor.

Ha! Yes, you are right, the ol' nerd-meter is pretty well pegged. :lol: I'm not Hawaiian (I come from English waspy stock, but my family's been in California for 5 generations...), but I am pretty big (6-3 240...) so it does probably look pretty ridiculous.

I'm getting too old for this sort of excitement, though. I don't think my heart has raced that fast since I was just out of high school and went skinny-dipping with three girls I met in Yosemite.

 

[recumpence]

One thing to consider on this too, is chain clearance with a huge rear sprocket.

I think single stage drive like this is the future of this hobby. However, only a few frames allow for chain clearance on this. That is what pushed me into multi stage to begin with.

Please understand, I believe single stage is definately the answer. I think we have all known that for a long time. It is merely the application of this that is the sticky part.

We should start making a list of frames that have good clearance for such a drive, so those who want to implement this, can have a decent platform from which to start.

Matt

 

[John in CR]

We just need larger diameter motors to get the Kv lower.

John

 

[mclovin]

One thing to consider on this too, is chain clearance with a huge rear sprocket.

I think single stage drive like this is the future of this hobby. However, only a few frames allow for chain clearance on this. That is what pushed me into multi stage to begin with.

Please understand, I believe single stage is definately the answer. I think we have all known that for a long time. It is merely the application of this that is the sticky part.

We should start making a list of frames that have good clearance for such a drive, so those who want to implement this, can have a decent platform from which to start.

Matt

IMO what is needed, ultimatey, is a new class on bike components: hubs, frames and battery carriers designed a built from the ground up specifically for ebikes. But I'm sure you already thought of that too.

 

[recumpence]

Absolutely! The ultimate in human/electric hybrid transportation, IMO, is a prupose built E-bike with 3 ratios for motor, 8 ratios (at least) for the pedal side, sub 70 pound weight with a 50 mile range.

However, the elegence of Gary's single stage setup precludes the use of a prebuilt bike because the entire point of his built is simplicity of application to an existing bike.

Matt

 

[GGoodrum]

We just need larger diameter motors to get the Kv lower.

John

Unlike the hub motors, which typically only come in a few wind/kV choices, the 3210, 3215 and 3220 come in a wide choice of turns/kVs. You can get a 3220 with a kV as low as 28, which is close to hubmotor territory, but that would not like running at such a low voltage of 50V. Once we get sensored versions, however, that voltage could go up to say 100V, which opens up lots more possibilities for different setups and would ultimately allow even higher performance than we are seeing now. My 7-turn 3220 (kV: 97...) has some pretty incredible torque at the 45-50V limit of the RC controllers, but it isn't close to its optimum speed for max torque/efficiency, which would be at around 80V. In delta mode, however, the kV jumps up to 167, which is much closer to the optimum motor speed at 45-50V.

-- Gary

 

[GGoodrum]

One thing to consider on this too, is chain clearance with a huge rear sprocket.

This is another reason to go with the slightly finer pitched #219 chain. Even a 100t #219 sprocket would be a smaller diameter than my 94T #35 go kart racing sprocket I'm using now. It does take a bit more of a creative motor mount solution to get it to work, especially on a 20" folding bike, but I think I have a way. On the Port Runner, it was easier because there's no bottom chainstay, but I'm getting ready to redo the setup on my Mariner folding bike, which has a chainstay, so this will be a good test.

-- Gary

 

[mclovin]

Absolutely! The ultimate in human/electric hybrid transportation, IMO, is a prupose built E-bike with 3 ratios for motor, 8 ratios (at least) for the pedal side, sub 70 pound weight with a 50 mile range.

I like this design criteria.

However, the elegence of Gary's single stage setup precludes the use of a prebuilt bike because the entire point of his built is simplicity of application to an existing bike.

His set up is pretty elegant for sure...however...he, you and the other fine folks on ES are what I would characterize as high-knowledge builders. Many of us (I'm speaking generically) do not have access to machine shop equipment or a welding setup or have the fairly deep technical knowledge needed to build his ebike from scratch. But, if the building blocks were already developed (sweet frames, hubs, electrical "packages") then someone like me (an electrically challenged gear head without the benefit of much RC experience) could build a sweet bike starting at the component level. To be clear, DIY methods are great fun and I'm not afraid to solder in some extra caps on an ESC but I am afraid of unknowingly making a mistake and wasting money on a blown part.

I think there is a great opportunity here for a cottage industry but I'm sure you already knew that. :wink:

Cheers.

 

[Miles]

I think there is a great opportunity here for a cottage industry but I'm sure you already knew that. :wink:

Yeah, we're one big international cottage

 

[deecanio]

:lol: :lol: :lol:

 

[John in CR]

We just need larger diameter motors to get the Kv lower.

John

Unlike the hub motors, which typically only come in a few wind/kV choices, the 3210, 3215 and 3220 come in a wide choice of turns/kVs. You can get a 3220 with a kV as low as 28, which is close to hubmotor territory, but that would not like running at such a low voltage of 50V. Once we get sensored versions, however, that voltage could go up to say 100V, which opens up lots more possibilities for different setups and would ultimately allow even higher performance than we are seeing now. My 7-turn 3220 (kV: 97...) has some pretty incredible torque at the 45-50V limit of the RC controllers, but it isn't close to its optimum speed for max torque/efficiency, which would be at around 80V. In delta mode, however, the kV jumps up to 167, which is much closer to the optimum motor speed at 45-50V.

-- Gary

My point is that we need motors as well designed as these RC motors, but that are meant for ebikes, not driving propellers. I'm pretty confident that a larger diameter is the ideal we want. Guys can come up with all the beautiful multi-stage drive systems they want, but it's not the most efficient use of space, weight or battery. I thought we had a motor builder coming up with a purpose built motor, but that seems to have evaporated. The ideal Kv probably needs to be in the 12-20rpm/volt range, and once we remove the stresses of in-wheel mounting and allow for some ventilation, how lightweight can we go and still achieve those 90%+ efficiencies?

Let's not leave out ESC's...as attractive as the small size and weight is, the RC experts still blow theirs, and IMHO absolute dependability is paramount to EV's taking over transportation. I'm no E guru, but my untrained eye sees plenty of opportunity for a happy medium somewhere between current ebike controllers and RC controllers.

John

 

[spinningmagnets]

Matt said "...We should start making a list of frames that have good clearance for such a drive..." Here's a link with "large wheel folding bicycles". The blue Beach-cruiser shown is $500.

http://www.treehugger.com/files/2008/02/buygreen-large-wheel-folding-bikes.php

 

[spinningmagnets]

The Dahon Espresso is $370. Here's a recent list of folders, and a few of them might work for this.

http://www.optimalride.com/folding-bicycles/best-folding-bikes.html

 

[MitchJi]

Hi Miles,

Gary,

The advantage of using #219 is that the Extron composite sprockets (only available in that size) are a bit quieter.

I think the appearance, the lighter weight and slightly smaller pitch are equally good reasons.
http://www.cometkartsales.com/store/sprocket/extron.htm

# Made from Extremely durable composite construction
# Over 40% lighter than the leading aluminum sprocket
# Improved sprocket life
# Improved chain life
# Decreased chain noise

 

[GGoodrum]

Well, I'm all for quieter, that's for sure. : Today my wife and I took a ride, up to our local shopping center. It was 12 miles, round-trip, and almost all of it is pretty hilly. Lots of shifting, back and forth, between 2nd and 3rd. It makes the most noise when under max loads like this. My wife's Townie has a 5304 and a 12-cell PSI 72V setup, and it is definitely a hell of a lot quieter. I need to try a 12 or 13t motor sprocket, to see if that will help make it a bit stealthier.

-- Gary

 

[Miles]

My point is that we need motors as well designed as these RC motors, but that are meant for ebikes, not driving propellers. I'm pretty confident that a larger diameter is the ideal we want. Guys can come up with all the beautiful multi-stage drive systems they want, but it's not the most efficient use of space, weight or battery. I thought we had a motor builder coming up with a purpose built motor, but that seems to have evaporated. The ideal Kv probably needs to be in the 12-20rpm/volt range, and once we remove the stresses of in-wheel mounting and allow for some ventilation, how lightweight can we go and still achieve those 90%+ efficiencies?

A multi-stage system will usually be lighter.

One stage 'gearbox' plus reduction to wheel seems the best compromise for torque to weight versus efficiency.

Straight reduction to wheel seems the best compromise for efficiency & simplicity.

 

[lesdit]

I like how things are evolving here, it's a moving target as far as starting my own project!
Speaking of efficiencies, has anyone measured how many watts a dual reduction RC setup draws, let's say at 1/2 speed with the bike on a stand ? In other words, how many watts are used in spinning the belt and chains ?

 

[John in CR]

My point is that we need motors as well designed as these RC motors, but that are meant for ebikes, not driving propellers. I'm pretty confident that a larger diameter is the ideal we want. Guys can come up with all the beautiful multi-stage drive systems they want, but it's not the most efficient use of space, weight or battery. I thought we had a motor builder coming up with a purpose built motor, but that seems to have evaporated. The ideal Kv probably needs to be in the 12-20rpm/volt range, and once we remove the stresses of in-wheel mounting and allow for some ventilation, how lightweight can we go and still achieve those 90%+ efficiencies?

A multi-stage system will usually be lighter.

One stage 'gearbox' plus reduction to wheel seems the best compromise for torque to weight versus efficiency.

Straight reduction to wheel seems the best compromise for efficiency & simplicity.

I'd like to see a motor about halfway in size between a small direct drive hub motor and the motors found in the geared hub, but nicely ventilated instead of sealed. Now that I think about it, I have a geared hub with shot freewheel. I should take a look and evaluate running it without the cover. Just attach a drive sprocket at the sun gear, along with some larger size phase wires. The 500W48V rated motor should easily handle several Kw at 72V and well ventilated instead of sealed with no thermal route. Hmmm, I think I just figured out an easy route to a lightweight rig I want to try.

Too bad the phase wires are so darn spindly on the geared hubs I have, or I'd just ventilate the covers and wouldn't need a large sprocket at the rear wheel. Plus I wouldn't have the FW issues trying to be dealt with on the parallel drive thread. Just attach the drive sprocket to the cover, which freewheels, and screw on a FW or cassette to the existing threads to be driven by the cranks. 2 way Isolation or combined drive with a regular rear wheel, super easy to set up, small enough to put right on the swingarm just by going to a 20" wheel. Small wheel and a 3 speed hub, would give billy goat climbing even at a 1:1 sprocket ratio motor to wheel.

John