Nexus inter3 rules!

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bowljoman

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Aug 7, 2010
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Its the same hub, with coaster brake. THe Sturmey archer site does not show the driver sprocket. I assure you, the link at SJS and Niagara are the same hub model. src-3 = ts srf-3.

You are lucky if you can find a trike hub at all.

Why cant you use coaster brake version? Do you really plan on your engine spinning backwards? Ive yet to see an engine spin backwards and apply the brakes on a coaster hub.....

:p

If there is some other reason, just take out the pucks....

The only 3-speed hub that is different that the sram, sturmey-3, or inter-3. is a sturmey s3x fixed gear hub. THe advantage of the fixed gear hub jack-shaft is that you can roll-start a china girl through the hub.
 
d_gizzle

d_gizzle

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May 29, 2012
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Alright then Ill just get the one from Niagara. Thanks for the info.

Now about the gear ratios. I really just need to know what they mean by direct drive. It says a 1:1 ratio in 2nd gear but is that with a 22 tooth sprocket on both the input and the output? After that I just add or subtract 25% to get 1st and 3rd gears,right?
 
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bowljoman

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The ratios are not corresponding to the tooth count.

The ratio internal is consistent. The input sprocket can be 16 to 24 tooth.

Yes, the math is something like that.

It is a shame you cant see the flash calculator application. It covers everything from crankshaft to rear wheel size.
 
d_gizzle

d_gizzle

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I seen that it is exactly what I need for the math of the 'Suicide Scoot'.

But how do I figure out final drive ratio? If my math is right then 9:1 or 10:1 in second would be perfect for me.

My sprocket teeth count~

20T-72T=3.6:1

11T-22T=2:1

22T-30T=1.4:1

For a final ratio of about 10:1. But that's not right,right? Because of the internals?
 
d_gizzle

d_gizzle

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I seen that it is exactly what I need for the math of the 'Suicide Scoot'.

So how do I figure out final drive ratio? If my math is right then 9:1 or 10:1 in second would be perfect for me.

My sprocket teeth count~

20T-72T=3.6:1

11T-22T=2:1

22T-30T=1.4:1

For a final ratio of about 10:1. But that's not right,right? Because of the internals?
 
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bowljoman

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Aug 7, 2010
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I dont bother trying to figure the fabled 10 to 1 ratio. It only applies to a certain tire size(26 ") and a certain power band(weak 2 stroke).

The calculator really helps you after you have a real-world measurement. So take from other's experience that you can setup a 42-tooth rear wheel sprocket on a 26" wheel. If your crankshaft does not have reducer gears before the engine sprocket, it is harder.


input / output.
Something like this.

ratio = rearWHeelSprocket / (tranny-out/ (tranny-in / engine-out))

So set the rear wheel to 26", set the rear wheel sprocket to 42 teeth, and then put your crankshaft ratio where it should be...

First gear should be about 15-20 MPH at peak HP.
 
d_gizzle

d_gizzle

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I know what the hub ratio is. How do you think I got the 10:1 ratio?
And I need the freewheel hub because my rear sprocket will be solid mounted to a "12.5 inch" scooter wheel. When i coast the rear wheel will 'turn' the coaster brake. And I'd rather buy the REAL trike hub from the UK than alter a converted hub. If it was the same model hub it would have the same name on it. I will be emailing or calling sturmey archer to find out for certain later today.
 
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bowljoman

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Yeah, you're still missing the point that the rear sprocket on your wheel , which is fixed, will not engage the brake whether it is a coaster or not....


I too have a 12.5 inch wheel, and I too have a coaster-brake model.

And I WISH WISH WISH my rear wheel sprocket was fixed like yours, because it aids in shifting to have the rear wheel push the hub faster than the input sprocket.

So, again, it is perfectly fine to have a fixed sprocket on your rear tire while using a coaster brake jackshaft. To engage the brake, the engine sprocket must rotate backwards 1/4 turn. it will never engage by the rear wheel turning.


If you are designing a system that drives the hub into the sprocket rather than the conventional way of driving the sprocket into the hub, then all you need to do is remove the coaster brake shoes. Then the hub will drive in reverse.

BUT, you will find the sturmey archer may not shift while driving backwards, and that is true for some other roller clutch hubs. THey only shift out of first if rolling forward.

If you must drive a hub backwards, you need the S3X hub, or an older more-dangerous pawl-hub.
 
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bowljoman

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d_gizzle said:
And I'd rather buy the REAL trike hub from the UK than alter a converted hub. If it was the same model hub it would have the same name on it. I will be emailing or calling sturmey archer to find out for certain later today.
Click to expand...
Tricycle hubs are made as an after thought. THey are identical to the non-tricycle hubs. THe only difference in hubs is cargo/tandem or non-cargo/tandem. The trike hubs are not cargo-hubs.
 
d_gizzle

d_gizzle

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Man,I feel like an idiot right now. You are absolutey correct about the coaster. I haven't used a CB in,well,ever so I don't know why my mouth was open anyway. Thanks for clearing that up.

If you need a solid mount for your sprocket you just need one of these:

http://electricscooterparts.com/electricscooterwheels.html#.

With a top hat adapator and a sprocket for it. That's what I'm using. The rear wheel looks to wide for my scooter and I can't find any dimensions for it either. But the rear comes with freewheel threads/disc mount or freewheel/band brake.
 
d_gizzle

d_gizzle

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And is what you're saying about the hub ratio is if 2nd gear is 7.2:1,1st and 3rd gear change the hub ratio? Then I add the rear gear ratio to those three ratios?
 
d_gizzle

d_gizzle

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This is from Sheldon Brown's website:

¤
S-RC3
3 Wide
133.3
100
75
Aluminum-shell version of the AWC, with coaster brake
¤
TS-RF3
3 Wide
133.3
100
75
No brake, high-polish aluminum shell, reverse gear and second sprocket: made for a tricycle. This is a gearbox, not a hub, and must be used in an intermediate position on the frame, with two chains, because the second sprocket attaches at the spoke holes on the right side.
¤

The ratios are the same,and I'm sure so are the internals,but who wouldn't want reverse on a motorized bike/scooter/trike/quad?
 
Velodrome

Velodrome

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May 27, 2011
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d_gizzle said:
Man,I feel like an idiot right now. You are absolutey correct about the coaster. I haven't used a CB in,well,ever so I don't know why my mouth was open anyway. Thanks for clearing that up.

If you need a solid mount for your sprocket you just need one of these:

http://electricscooterparts.com/electricscooterwheels.html#.

With a top hat adapator and a sprocket for it. That's what I'm using. The rear wheel looks to wide for my scooter and I can't find any dimensions for it either. But the rear comes with freewheel threads/disc mount or freewheel/band brake.
Click to expand...
This I gotta see. You gonna do a build thread?
 
NEAT TIMES

NEAT TIMES

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May 28, 2008
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HI ALL

Bowljoman is putting all the torque stress into the back wheel. That takes the torque stress out of the 3 speed hub.

When racing 700 hp late model stock car yrs ago, never had driveshaft or 3 speed stock tranny problems because the gearing was in the Quick Change rear differential (rear axle). Ran the stock 3 speed tranny in high gear same as engine rpm.

Bowljoman may have less torque transfered to 3 his speed than an original pedal powered bike, imho.

Just thought this may help some members.

Ron
 
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