Shimano Geared Hub and Jackshaft?

[mikegrundvig]

I've got a bonus check coming and I'm going to spend a good bit of the money on high-quality bike that I can use for many years to come. So my first (of many I suspect) question is this:

Can I get away with using a jackshaft combined with a Shimano Alfine or Nexus internally geared hub so the motor is benefiting from the gears of the hub? The jackshaft would require two freewheels - one for the pedals, one for the motor, then it would be tied to the rear sprocket for the rest. While this adds some complexity, I think the benefits of the gearing are pretty huge and let me use a smaller motor and get both a higher top speed AND better torque than a fixed gearing equivalent. Anyone have any thoughts on this? I'm very interested in everyone's opinion. Thanks!

-Mike

 

[StudEbiker]

You may want to consider the Sturmey-Archer 3x9. Here are a couple of threads where people have used them.

http://endless-sphere.com/forums/viewtopic.php?f=28&t=24274&hilit=+sturmey+archer

http://endless-sphere.com/forums/viewtopic.php?f=28&t=25591&hilit=+sturmey+archer

 

[mikegrundvig]

Those threads were pretty interesting and informative. What is the advantage of the SA over the Shimano? I'm a little confused about why to choose one over the other.

-Mike

 

[Rassy]

I used the Shimano Nexus 8 speed and am fairly happy with it. My main concern is whatever allows it to slip when applying high torque in 8th gear. I.e., if I don't shift down when going up a steep hill there will be an occasional slip somewhere. However, it has been in use for over a year, and still works perfectly. Since I try not to pull over 10 amps (500 watts), I only run into this issue when not paying attention.

Another option might be the Nuvinci CVT. LI-ghtcycle likes his setup

And, I don't use a jackshaft, since my motor is a low speed hub motor used as a mid-drive.

 

[mikegrundvig]

Thanks Rassy; I've read your threads and learned a good bit. So now I'm more confused than ever... If these adapters are available:

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=17602

Then I believe I can just run two of those together on the rear hub - Nexus or Alfine. Is that correct? That eliminates the need for a jackshaft which I REALLY like.

-Mike

 

[Rassy]

So now I'm more confused than ever... If these adapters are available

Mike, if this comment was directed at me, I don't have any answer. My mid-drive motor just pulls on the same chain the pedals pull on so there are no adapters used, just standard off the shelf freewheels, etc.

 

[spinningmagnets]

You may have misunderstood the thread you linked to, the Nexus and Alfine cannot accept two independent Freewheels since they do not have the splined freehub (GGoodrum has an adapter that has two freewheels, with only one being independent). The SRAM-Dual-Drive is a combination of a 3-speed Internally-Geared-Hub (IGH), and a splined freehub, onto which certain types of chain-cogs can be installed, which use the common external derailler.

The original intent was that the internal 3-speed would replace the front Bottom-Bracket (BB, the pedal axle) so that instead of having three external chainrings on the BB, there is only a single chainring, and the 3-speed + the 5 external cogs would result in a 15-speed bike with a single chainring in front.

This also allows the user to change the entire gearing group for flat land or hills, by simply changing the single front chainring. Broaching is a machining method that pushes a cutting-tool through something with a high-pressure press, and it leaves behind grooves. The White Industries ENO freewheel (FW) is very strong, and the inner race is not hardened steel, which allows the ENO ID to be broached so that it will slide onto any splined freehub.

The common freehub will only accomodate two side-by-side FWs. The SRAM-DD combined with 2 broached ENOs allows the motor and also the pedals to each have 3 gears, while maintaining total independance from each other. The pedals do not require a FW with the strength of the ENO, but the inner races of common FWs are hardened, and cannot be broached, though a few have used a hand-file to make the spline-grooves in a cheap Dicta BMX FW (in order to save a few dollars)

IIRC the ENO is about $120, and the SRAM-DD is around $240, and a Dicta can be had for around $20 (prices are averaged, and include tax/shipping). Giving the motor 3-speeds will help motor and controller heat, and will also make life easier on a C-rate limited battery pack by reducing the max amp-draw (if loads are constant compared to a 1-speed motor-chain), however...this is about $400, and thats before you add the bike, motor, battery, etc...

edit: if you want a splined ENO, the process is to PM LFP and ask if he is still involved in that and ask what the broaching cost is. You would buy an ENO, and mark the delivery to the address LFP gives you.

 

[mikegrundvig]

Gah, I assumed the Shimano had the standard splines and could support the twin freewheels. I see instead that it has an odd three lobe thing. I hate how few standards there are in bikes!

I REALLY want a solution that gives me a fair number of gears or I'll just end up using the motor constantly and not peddling like I should. I'd like to avoid working it into a standard derailleur system if I can as that would be nasty. Sounds like the jackshaft solution is still the only realistic way to go if I want to use a global gear mechanism. That, or this one which I'm having a hell of a time following:

http://www.endless-sphere.com/forums/viewtopic.php?t=23861

-Mike

 

[amberwolf]

Well, one option is to use two 3-speed geared hubs (IGH)...one in the wheel, and one as the jackshaft. If the motor only needs three gears, then drive the jackshaft hub's shell directly with the motor's output, and drive the jackshaft's input sprocket with the pedal chain.

Then you get three more gears for pedalling, if you need them, and just the one for the motor.

I do recommend some sort of either slipper clutch for the motor, or rubber mounting spacers for the sprocket on it (like a "floating" disc brake rotor). That way the motor can't hammer the IGH so hard that it shears teeth off the sun gear (a problem encountered by a few people driving an IGH with a powerful enough motor).

Alternately, some sort of throttle ramp-up so it won't just suddenly apply full power to it, even by accident.


There are a number of jackshaft setups that have been done or conceived of. My original powerchair motor system for CrazyBike2 did this, using the second BB on the bike (it's so long there are two) as both the jackshaft for those inputs and as the front chainrings for the regular bike drivetrain; pedals were on the front BB.

A reconceived version of this bike is in progress, and will use a hubmotor driving a NuVinci as a jackshaft, with both pedals and motor inputting into the sprocket side of it.

There are also a few other NuVinci builds in progress now, some of which will use a jackshaft to feed the NV or the NV as the jackshaft.

 

[Miles]

I see instead that it has an odd three lobe thing. I hate how few standards there are in bikes!

It's as much a "standard" as the 9-spline cassette driver is....

 

[MitchJi]

Hi,

Gah, I assumed the Shimano had the standard splines and could support the twin freewheels. I see instead that it has an odd three lobe thing. I hate how few standards there are in bikes!

The issue isn't the number of splines. The issue is that the SRAM dual drive is the only IGH on the market designed to accommodate derailleurs on the rear, so its the only IGH with room for dual FW's.

Can I get away with using a jackshaft combined with a Shimano Alfine or Nexus internally geared hub so the motor is benefiting from the gears of the hub? The jackshaft would require two freewheels - one for the pedals, one for the motor, then it would be tied to the rear sprocket for the rest. While this adds some complexity, I think the benefits of the gearing are pretty huge and let me use a smaller motor and get both a higher top speed AND better torque than a fixed gearing equivalent. Anyone have any thoughts on this? I'm very interested in everyone's opinion. Thanks!

Very elegant (IMO) solution but a lot more work to implement. Something like the following using a jackshaft in place of the hub motor:

I REALLY want a solution that gives me a fair number of gears or I'll just end up using the motor constantly and not peddling like I should. I'd like to avoid working it into a standard derailleur system if I can as that would be nasty. Sounds like the jackshaft solution is still the only realistic way to go if I want to use a global gear mechanism. That, or this one which I'm having a hell of a time following:

That's a complicated example. All you need is Cranks with a freewheeling chainring driven (a lot more information here) by the motor so that the motor doesn't back-drive the pedals and a FW on the motor output so you can pedal without driving the motor.

Using a jackshaft to emulate something similar to the pictured bike has some advantages but it will require a lot more work to implement. Unless there is a feature or features that are really important to you I'd just drive through a chainring with a FW.

 

[Chalo]

The issue isn't the number of splines. The issue is that the SRAM dual drive is the only IGH on the market designed to accommodate derailleurs on the rear, so its the only IGH with room for dual FW's.

Your information is out of date. Sunrace/Sturmey Archer makes a cassette hub with a 3-speed internal gearbox.

And SRAM has withdrawn its internally geared hubs from the US market.

Chalo