Power transmission through a 3 speed hub?

I've had my ebike set up with a 11.75 gearing and a 1hp scott motor and it will pull up any of the hills around here. But its a dog on the flats 20-22mph is about max. So I though about changing out my current jack shaft for a sturmey-archer AW 3 speed hub. With the hubs 1.3 - 1 - 0.75 gearing it would give me a 11.73 hill gear, a 8.88 1:1 normal gear, and a 6.65 speed gear.

But the problem I'm thinking is the old 3 speed hub old up to a 1hp 10ftlb motor? I dont want to destroy a nice hub just to test it. (plus I would be out $30)

Anyone try to use a 3 speed hub with the motor on a ebike before?

I think it's worth the $30 to find out, but that's just me.

DeathBlade said:

I dont want to destroy a nice hub just to test it. (plus I would be out $30)

Click to expand...

turn in ur avatar.

use the search, i think it wuz 'safe' who said it can handle a horse since a motor is smooth continuous power whereas pedal input has peaks exceeding 3(?) hp from a human bean, fwiw.

I would be interested to see how you plan to use the hub as a jackshaft. I was thinking of doing something similar with my RC setup, but didn't know how to attach a pulley to the hub without ruining it. My plan was to use all the spoke holes and use tiny screws in each hole.

Horsepower means nothing, in this case.

The torque at a specific point in a transmission is inversely proportional to the velocity.

So, if you are running an internal hub as a jackshaft, the torque through it will be reduced by the ratio of the gear reduction between it and the wheel.

Also bear in mind that the wheel size affects the level of torque passing through a hub gear......

etard said:

I would be interested to see how you plan to use the hub as a jackshaft. I was thinking of doing something similar with my RC setup, but didn't know how to attach a pulley to the hub without ruining it. My plan was to use all the spoke holes and use tiny screws in each hole.

Click to expand...

I was planning on turning down the oppisite side from the drive sprocket and brazing on a small piece of pipe with a keyway cut into it and then using set screws to hold on the second sprocket.

I wanna know where you got the AW for $30?

I paid $60 for mine plus shipping.

I plan on machining a 90 tooth GT2 pulley to fit
the sturmey 3 tooth sprocket input interface similar to the
gates carbon drive for bikes. They make a pulley
that will fit a Nexus drive(same 3 tooth Sturmey design), but only for the 8mm pulley pitch in a
24 tooth size special carbon drive stuff.

If you search, you'll find that Sturmey makes a hub
drive for quadracycles and tricycles for use as an intermediate
drive. all they do is what you guys have mentioned, they
use the spoke flange as a mounting flange for a sprocket.
However, this only works for the output (I think, somebody correct me if I'm wrong
, I'm no planetary drive expert).
So, I plan on going the bmx route for sprockets and machining
a sprocket to fit the spoke flange of the AW.

The Sturmey 5 speeds are really cool as well.
and the 8 speeds, and the shimanos, and the SRAMs and the Rohloffs...
yikes..
But, the best value is definitely the AW 3 speed on a price per gear range basis.

You might consider modding the edge of the hub's endcap to accept some sort of adapter. That could take a bit of load off the flange.

The pipe mod might be hard to center.

12p3phPMDC said:

I wanna know where you got the AW for $30?

I paid $60 for mine plus shipping.

I plan on machining a 90 tooth GT2 pulley to fit
the sturmey 3 tooth sprocket input interface similar to the
gates carbon drive for bikes. They make a pulley
that will fit a Nexus drive(same 3 tooth Sturmey design), but only for the 8mm pulley pitch in a
24 tooth size special carbon drive stuff.

If you search, you'll find that Sturmey makes a hub
drive for quadracycles and tricycles for use as an intermediate
drive. all they do is what you guys have mentioned, they
use the spoke flange as a mounting flange for a sprocket.
However, this only works for the output (I think, somebody correct me if I'm wrong
, I'm no planetary drive expert).
So, I plan on going the bmx route for sprockets and machining
a sprocket to fit the spoke flange of the AW.

The Sturmey 5 speeds are really cool as well.
and the 8 speeds, and the shimanos, and the SRAMs and the Rohloffs...
yikes..
But, the best value is definitely the AW 3 speed on a price per gear range basis.

Click to expand...

You do get the AW's come up on e-bay going for as little as £5.00, I paid £7.00 for the one I got. And I just got a SRAM P5 for £20.00 .

nice! I'm jealous. I guess I better check out ebay.

So, I attached my gearing spreadsheet.
You can enter Kv, battery volts,pulley 1 and pulley 2 reduction sizes
and a final reduction along with your wheel diameter.
You can change the ratios if you like, but I plugged
them in from my research on the net.

Sorry, it's all in inches, mph, ft/min, and well volts is volts.
But that's easy enough to convert to this metric funny business.

With an 8 speed Shimano Nexus intermediate drive....you can have
a crazy range of speeds! spend $1400 on a Rohloff tranny and
you could be in e-bike heaven if you don't kill yourself trying.
(Think LandSpeed e-bike!, aero package may be required)

So, anyway, $60 dollars on a 3 speed ain't too bad at all to see
if this crap will work. Maybe a 5 speed, it sure gives a nice range
and it'll be like driving a car with a manual.

Sjs Cycles in England sells the quadra and tricycle sturmey intermediate drives
with sprocket on the flange. Hell they even have one with reverse!

http://www.sjscycles.co.uk/product.asp?pf_id=19015&changecurrency=USD

I have two bikes with 3-speed hubs, and one with a Nexus-8. All eventually will get RC-based setups. The bike in my avatar is a 20" folding bike, with a Cyclone 1000W setup and a Nexus 3-speed hub. It used a 16s5p 48V/11.5Ah pack and hit peaks of 2650W. I "played" with the gearing a bit too much and it had way too much torque in 1st, and my mods made the pedals pretty useless, even in 3rd. The Cyclone setup used a 6T/44T chain drive to the front crank, and then came with a 36T chainring to drive the rear. I was worried there wouldn't be enough low-end torque, so I change the 36T for a 24T "granny gear", and changed the stock 18T cog on the hub to a 23T, so I could get pretty close to a 1:1 front-to-back ratio. If I had it to do over, I would have left the 36T alone, but maybe still swapped the 23T for the 18T in back.

I've already taken off the Cyclone setup, and it is in the midst of getting an AstroFlight 3210, along with one of Matt's drives, with a 70T/17T belt drive. The output shaft of this has a 12T track cog and will drive a 53T chainring on the crank. There will be a 40T chainring to drive the hub, which will retain the 23T cog that is on there now. That is a total reduction of (70/17) * (53/12) * (23/40), or 4.12 * 4.42 * .575 = 10.46:1 in 2nd, which is 1:1. In first, the ratio goes up to 14.33:1, and in 3rd, down to 7.69:1. That translates to 24.4 mph top speed in 1st, 33.5 mph in 2nd and 45.5 mph in 3rd. By comparison, the Cyclone 1000W setup topped out at 18.9 mph in 1st, 25.8 mph in 2nd and 35.1 mph in 3rd. I'll never need 45 mph on a folding bike, but this compromise gearing setup makes the pedals useful again.

I also have a 16" folding bike that has a 3-speed SRAM hub. It is going to also get an RC-based setup, but with a slightly different configuration.

-- Gary

GGoodrum,

What is your impression of the multispeed planetary hubs? I remember riding a three speed back in the day when I was a kid
at my uncles place. It intrigued me enough to remember it and that it was simple. I've read reviews on them, but I've never heard anyone talk about putting down 1000W to 2500 peak through them. As others have mentioned, human peak power can put large impulses into a drive, therefore, I'm of the opinion that the planetaries will be stout enough to take the kind of loads that we are talking about. How do you shift it? Do you drop throttle for a sec(or until freewheel), shift and resume? Do you jamb it in there? What kind of abuse have you hit it with under load? Do they misshift on you? are they super smooth...sorry with the questions, but I'm digging for planetary drive experience here! Do they give you trouble with 10x human power?

On a granny trike i have used both a Nexus 3spd and a Nexus 4spd hub used as a jackshaft. the motor was a 500W Cyclone. iit has drawn 40A peaks @24V = 1000W.

I know that that is lower than what you are talking about, but there was never any mechanical trouble with either. and i am talking about a 250lb rider on a heavy steel frame trike with a couple of 40Ahr SLAs. maybe i wasn't working the hub on the input side but i was definitetly using it on the output side.

now how well it would survive with 2KW or 3KW input and the same kind of output load may be a different story. but the results with 1000W are encouraging enough for me to risk it if i had a motor big enough.

rick

Rick,

Awesome... 8)

Hey thanks for the input....

How did you shift it....do you just jamb it in there, shift on fly? Do you cut throttle then shift?

Do you know if you can buy just the spoke-flange mounted sprocket? How many teeth did the jackshaft
output sprocket have? Where did you buy the hubs/jackshafts from? SJ Cycles?

anyway, my confidence in these hubs is growing. We will see!

Chris

I know a guy in San Diego who makes custom chopper-styled bikes with Etek and Mars motors, running through Nexus-3 hubs, and he's never had a problem. That's actually why I picked the Nexus-3, and I got it from him. The bike originally had a 7-speed derailleur setup.

As for shifting, I think you can do it on the fly, but on mine, I had the shifter and a half-twist throttle on the same side, so I had to let go of the throttle to shift. It likes to stay in 2nd, and it takes just slightly more force to go up to 3rd, or down to 1st.

-- Gary

Thanks Gary.

Right on.....fun stuff!!!

yea, I think that Schwinn sold Nexus hubs on there chopper style bikes. The model they use
is longer than the AW that I bought. The long hub is used for those fatty chopper tires. The only place I could find a 3 speed with disc brake 6 bolt was from a bike chopper place, same kind of deal. In the end, I went with the 3 speed.
A 5 speed is only 100 bones and gives a nice range of gears.

I think that these are hubs are the easiest tranny to integrate. The 2 speed thread has some cool ideas, etc...
but, it's hard to beat these hub drives in terms of simplicity, amazingly tight package, sealed, etc..etc...

I think that the nexus 8 speed hubs would be an amazing thing to have on one these bikes. A compound series drive
with two of these would be cheaper than a rolhoff by more than half including integration. 64 combos is a lot,
so you may want a 3 - 8 series combo. 8 speeds give you like a 300% range anyway. 30 mph to 90 mph if you can actually push it that high.

The nexus 8 has an underdrive, whereas the sturmey 8 speed is direct then all overdrive. At least the 3 and 5 speed sturmeys are underdrive ...direct....then overdrive. Seems like such a small detail, but when you pile on all of the other constraints we face, the underdrive really helps when it comes down to picking the gearing. Gary, you've mentioned that several times as well..

Chris,

The thing to avoid with these hubs is shock loads. So, a chain drive direct to a high torque motor is more risky than a dual stage synchro belt drive to a low torque/high speed RC motor, everything else being equal.

A hub which will be interesting for us, is the new SA fixed gear 3 speed. Although it has relatively close ratios, both are underdrives (direct-drive is top gear). Being a fixed gear hub, it also has the potential to be used for regen.... Also, the Shimano spec., splined input driver is arguably more adaptable, for custom set-ups. http://sunrace-sturmeyarcher.blogspot.com/

Maybe the shock loads may just go to the small contact patch on the tire
where it'll just break the rear end loose. Are you guys doing burnouts??!?
(i know some of you guys are)

Yea, that fixie 3 speed is cool. You're right, the shimano interface
is nice for custom setups....that gives you alot of
options on cogs and custom pulleys...alot more of the "id" of a custom shimano
pulley would engage the teeth and won't have the loose fit that causes slight slop
in the plane of the sprocket due to the spring clip retention on the old style and the narrow cog.
It would be tight!

I downloaded the new SA catalog.
The reversible hub for 5 speeds is pretty cool
for somebody wanting to do a velomobile electric.
But with the fixed 3 speed, you could just reverse the motor plus regen like you said.

I

Unless you are needing the extra gears for pedaling, a motor setup is not like to even need more than 2-3 gears, period. With the Cyclone setup, I usually started in second, which is 1:1, and then shifted to 3rd pretty quick. The only time I used 1st was starting out at the bottom of a steep hill.

-- Gary

12p3phPMDC said:

Rick,

<snip>
How did you shift it....do you just jamb it in there, shift on fly? Do you cut throttle then shift?

<snip>
Chris

Click to expand...

the 4spd was an AUTO-D. It came from shimano with a speed sensor and a sevo motor and was fully automatic. it shifted on the fly all of the time. the part number is SG-4C35 for the system. i removed it from a wrecked bike i bougth at the annual police auction. i drilled and boltes a 36 tooth chainring to the left side spoke flange. i mounted a matching 36 tooth to the rear axle.

the auto shift 4 spd replaced the 3spd that came stock on the trike. the 3 spd was a manual shift and i also shifyed it on the fly. the 4spd automatic was an upgradde.

both use 21 tooth input sprockets. but they are chageable and several sizes are available. the 20 tooth output sprocket of the 3 speed is welded in the same place as the right side spoke flange. part number is SG-3C41.

rick

Automatic??!?!? what...that's too cool !! Thanks for throwing that part number out
there. Now I can make it even more complicated!! :wink:

We can hack it and turn into push button controlled
manu-matic paddle shift mammahamma.

You can also get an auto version of the Shimano 8 speed hub:
http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/products/city___comfort_bike/cyber_nexus.html

looks complicated, but so are alot of things..

Looks like shimano already took care of the manumatic.

dead simple. it comes with a little control box mounted to the handlebars. you can select manual or auto shift via a switch and there are up and down push buttons for shifting. it also has a speed display. it is also programmable for wheel diameter.

there is also an auto shifter for the 3 speed shimano hub part number AI-3S30. the motor unit on this one mounts to the frame and it controls the shift cable so it can be added to any of shimano's 3spd internal hubs.

unfortunatetly it is not sold in the US or Canada. Shimano in north America will not get any parts for it. and the EU service and repair depots refuse to talk to me about getting one. they just refer me to the US office.

I wonder if on of our EU cousins could look into a price for one?

rick

well, complicated in relative sense, like a TH350 and a 4LE60.
both have planetary gears, oil pumps, and clutches, but one of them has electronics.

So, for the secondary stage on my drive, I'm gonna abandon the idea of modifying a gt2 pulley to fit the Sturmey
and use chain. It would have worked, no doubt about it. See pic from Gates Carbon drive for bikes.

But, initially, I wanted to do a single reduction and those large pulleys are way too big for the small space I have. So, since I'm doing a double reduction now, the off the shelf cogs give me enough reduction on the secondary stage so that I don't need to reinvent the wheel.

The smallest track cog I can find is 12 teeth and the largest for the Sturmey is 25 for ~2:1 reduction off the shelf.