Ev Bike drive/gearing design

this is a place to put bike design ideas concepts inovations etc...

1. running motor off rear left side internal 3 spd hub. right side could have small cluster added for conventional deraileur set-up

1a. central mounted motor running off rear left side internal 3 spd
hub.right side could have small cluster added for conventional
deraileur set-up

2. central mounted engine running off common free wheeled drive/crank
sprocket with 3 spd hub or conventional cluster gears in back

2a. central mounted engine running seperately off right rear 3 spd
geared hub with extra sprocket for added manual pedaling.

3. Bottom bracket mounted motor (cyclone)

3a. motorized bottom bracket (optibike)

3b. motor enclosed bottom bracket mounted (Giant L.A. Free or Twist
Gazelle easy glider)

4.Transmision Enclosed Bottom bracket (motor mounted seperately)

4a. motorized transmision enclosed bottom bracket

kisshu said:

this is a place to put bike design ideas concepts inovations etc...

Click to expand...

Yes it is...

The idea of introducing the multispeed hub before you even get to the rear wheel was sent to me as an idea by email. (possibly from some activity going on elsewhere I don't know) The big advantage is that you can obtain the gearing ability BEFORE the major geardown to the rear wheel. The net result is that you expose your hub to much less torque (since torque is associated with gearing... the lower the final gear the higher the torque) and that means less breakage potential.

A very good idea...

On the flip side the extra rpms going through the hub will increase heat... so what you protect yourself from (torque) comes back in a new danger which is the friction induced heat.

On my transaxle I had been using standard bicycle hub grease and I had found that it would completely break down into a sort of liquid. It would essentially fail to lubricate after a while. I switched to a higher grade (thicker) wheel bearing grease and have found that this grease can survive the heat. (and the bearings are no longer wearing out)

So it might be a good idea with such a setup to clean and rebuild your multispeed hub with thicker grease rather than light oil or bicycle grease.

safe said:

The idea of introducing the multispeed hub before you even get to the rear wheel was sent to me as an idea by email. (possibly from some activity going on elsewhere I don't know) The big advantage is that you can obtain the gearing ability BEFORE the major geardown to the rear wheel. The net result is that you expose your hub to much less torque (since torque is associated with gearing... the lower the final gear the higher the torque) and that means less breakage potential.

A very good idea...

Click to expand...

Yes, way to go...

Even for pedal bikes, it has advantages... http://www.g-boxx.org/

Oh - My - God (that's wild)

http://www.srsuntour-cycling.com/SID=si398dbde7b671703a667e875cda4840/index.php?screen=sh.detail&tnid=1555

kisshu said:

2. central mounted engine running off common free wheeled drive/crank sprocket
with 3 spd hub or conventional cluster gears in back
.

Click to expand...

here's mine like that..

Version 1.0




This configuration with a 9 tooth motor gear and a 90 tooth crank gear along with a 24 tooth chainring resulted in a top speed of ~24 mph in top gear. However whenever you wanted to pedal it was rather retarded with only the 24 tooth front chainring.... I also didn't like my motor mount so I revised...

Version 1.1
This bike has a lashout gearhead, 4.7-1 ratio then goes from a 17 tooth motor gear to a 90 tooth chainring resulting in a cadence of about 112.
This version has a chain tensioner and a little different motor mount utilizing the water bottle holder bolts. This has a 26, 39 and 52 tooth chainring on the crank. This results in a range of speeds from 9mph to 30.6 (theoretically) more realistically a top speed of ~25mph without wind.

I have been riding this version to work for about 10 days (only 6 workdays) and haven't riden every day but I have riden ~155 miles in the last 10 days. I average anywhere from 20mph to ~24 mph depending on wind, and with a tailwind today I averaged ~26 on the way there and about 19 with the headwind in the afternoon (a vicious headwind)

Anyway Heres what I built..





~Sean
http://www.flickr.com/photos/7205482@N03/sets/72157600395113016/

Now that's a nice setup 8)

It's possible to mount a BMC motor to one of those planetary reduction units.

How did you do the freewheel between the crank and the chainring?

fechter said:

Now that's a nice setup 8)

It's possible to mount a BMC motor to one of those planetary reduction units.

How did you do the freewheel between the crank and the chainring?

Click to expand...

The planetary head also would fit a BMC with NO modifications.

The freewheeling crank was one purchased as an IPS however I wouldn't purchase one again I will make my next ones with Freewheels as I am very disatisfied with the quality of the product. It has lateral play that I find unacceptable.

I have 3 more Kols so I want to try one with more volts and an external controller.. if that really isn't enough I will go with a BMC.

I am already getting 25 mph w/out peddaling with a 400w? motor at 24 V and only a 30Amp fuse. With it running at 48 Volts I Imagine I will have a Lot more torque and top speed of ~35 or >...

fechter said:

It's possible to mount a BMC motor to one of those planetary reduction units.

Click to expand...

That would make things very easy. Take a BMC motor and use the planetary reduction unit to drop the gear ratio down to a level that you can handle. Very nice setup.

sean said:

The planetary head also would fit a BMC with NO modifications.

Click to expand...

It seems there are two different shaft options with the BMC motors. The ones used on the USPD have the shaft that works with the planetary reducer.

The ones used on scooters have the 12mm smooth shaft, which won't fit the planetary. It is possible to use a grinder to make one of these shafts fit, but it's a tricky process.

The Kollmorgen motor should fly at 48v. Knoxie says they fly apart at around 60v.

Another nice thing about using an external controller is you can make the motor about 1/2" thinner by getting rid of the internal controller and making a new cover from sheet metal. It would look cool if you drilled out the hall sensor board and made a clear plastic motor cover so you could see the insides of the motor.

Ok ... here's my idea (more of a combination of ideas already in production). Forgive me if I'm a little loose with the terminology. Obviously, I'm leaving out specific controller, battery, and motor selection/specs.

1. Optibike style frame, motor location and internal batteries.
2. Driveshaft (no chain) from pedals goes to right, rear hub.
3. Second driveshaft going from motor to right, rear hub.
(Two driveshafts possibly encased in single "chain stay." Two driveshafts may not be necessary. I wish I could get a conceptual grip on how the Optibike outputs pedal and motor power into a single chain. Anybody have some better pictures?)
4. Freewheel in between driveshaft inputs on hub.
5. Output of the 2 driveshafts goes into a NuVinci gearbox, then to wheel.
6. NuVinci gearbox is controlled by computer and servos mappable by user. Basic efficiency, mid, and all-out modes can be selected by user.
7. Front fairing.

I haven't tried to draw anything, but here's the basic concepts from pictures at

http://www.optibike.com, http://www.sussex.com, http://www.staton-inc.com, http://www.fallbrooktech.com, and http://www.zzipper.com

I haven't quite figured out how the driveshaft from the motor to the hub works with a rear suspension (not an engineer here). The sussex bike design of the driveshaft going from the pedal to the hub looks like it works well, but the introduction of a motor in an optibike style location would complicate things.

So, basically, the goal would be to have an Optibike style bike with a drive shaft instead of chain drive, computer mapped/controlled NuVinci gearing, and a decent front fairing. (and all the volts, amps, amphours, discharge rates, etc. that could be run while maintaining a fairly stealth look).

Leaving aside the technical difficulties of implementing your system....

Driveshafts with bevel gears are a bit less efficient, and usually heavier, than chain drives.

The Nu Vinci hub would be 4.2 Kg of unsprung mass - better to keep it out of the wheel.... :wink:

I've always thought that the Rans "crank forward" bikes (your last photo) had great conversion potential

Miles,

Your points are well taken. I like the shaft drive/Nuvinci concept for several reasons. The first primarily comes from my experience with admittedly less than high end chain bikes (Giant Iguana). The shifting on the bike was often a pain, particularly with upshifting. Sometimes it would take 5-10 seconds to get the dang thing to upshift. This was even after it was gone over by the LBS. Because the NuVinci does not use multiple sprockets, changing gear should be very smooth and immediate. In addition, the infinite gear ranges should make it no problem to find the perfect gear. Further, the ability to map out the shifts should make it easier to get into the most efficient gear for the circumstances (would this make up for the 3% or so less efficiency of the driveshaft vs. chain?)(cost considerations aside).

I also like the shaft concept because there's nothing to get pant legs caught in, fingers caught in, and it should be easier to keep it in appropriate adjustment. It's also cleaner, so there should be no grease on pant legs. These things can be very important to a commuter. From what I've read, the difference in a chain drive bike vs. a shaft drive bike is about 1 pound, and I'm pretty sure its not all in the drivshaft/bevel gears itself. Not having the background, I can't tell you how big of a difference this would be in real-life.

Its true that the NuVinci has more unsprung weight. Not as much as a hub motor though, although maybe the hub motor makes up for it with more torque?

If it would be better to put the transmission at the crank, how about something like this? This is obviously not to scale, does not include gear ratios, and the NuVinci gearbox would have an output shaft, as opposed to rotating the whole unit like the bicycle design appears to.

primalfuture,

You could always enclose the chain..... in the swingarm, even, like the Nicolai bikes.

It's fun to play around with ideas but, if this is your first project, I'd start with something much simpler.

In your new schematic, you only have 1 freewheel. Don't you want one for the motor, as well?

Miles,

Just fantasizing here. You've probably figured out, I don't have the technical expertise, yet? to pull something like this off. You're right about the freewheel for the motor. Gotta have 2 or downhill coasting could really mess things up. Would you put the 2nd freewheel in between the motor and the transmission, or in between the transmission and the driveshaft?

primalfuture said:

Miles,
Just fantasizing here.

Click to expand...

No harm in that

If you want to fantasize in 3D, you can use the free Alibre Xpress: http://www.alibre.com/xpress/software/alibre-design-xpress.asp