Jackshaft Advice on IGH as a jackshaft 4 my bikee e2 recumbent, already with GX35 and Nuvinci?

bigoilbob

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Soliciting advice, and candid comments on practicality. My overlong videos and explanation of my bikee e2 with a GX35 and a Nuvinci Developers kit are linked.

The bike has been great, taking my wife and I all over south St. Louis this summer. It's fun squeezing thru traffic at crowded summer outdoor events and parking close to the action. What I would like, in addition to the hill climbing ability and automatic transmission is an overdrive and underdrive. Even though the bike is heavy (well over 100#) and poorly powered (GX35 thru a Staton trihybrid gearbox and Nuvinci hub), it has very little drag or wind resistance. So, even with 2 aboard, on level roads we rev out at ~19 m/h and the tiny engine spins freely. I think if I had the 33% overdrive of, say, a Sturmey Archer 3 speed IGH, acting as a jackshaft, we would be safe at ~25 m/h. I could also winch up ~24% grades, up from ~18% grades now, with 2 aboard, in the "underdrive" low range. I have a great IGH mounting point on my heavy outboard motor mounts (visible in videos), and the Nuvinci hub freewheels, so no problems there.

I would like forum input on;

* What would be the best IGH? The SA seems strong, especially if I transmit the power at a higher r/m. But the Shimano 3 speed has an available electric shift, and I have a constant 12 volt power source.
* Does the 90-95" distance from my left hand grip (preferable shift point) to the IGH mounting point make the installation impractical?
* Are there any kits or other cheats a non welder could employ to install the second sprocket?
* Post mortem assessments from anyone who has tried this, on any MB.

Not that worried about $. I have about the same brains/money ratio as Jay Leno, if at a much, much, lower level.

Thanks, and don't hold back if it's a really stupid idea.


http://www.motoredbikes.com/showthread.php?39332-Powered-BikeE2-Recumbent-Tandem-Long-Description-and-Video
 

bigoilbob

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No response, so I think I might have done a poor job explaining myself. Let me try this. Has anybody installed the sturmey archer/station hub kit http://www.staton-inc.com/store/pro...RIKE_HUB_CB_CONV_KIT_STURMEY_ARCHER-84-0.html on a bike. These, on trikes, are functionally "jack shafts".

The idea would be to cruise most of time in "2" (1/1 input/output ratio), using the NuVinci auto shift, with it's ~3.6/1 low/high spread. When I was on smooth, level road, go to high (0.75/1 input/output ratio), and when in San Francisco and the need arose, got to low (1.33/1 input/output ratio), admittedly torquing hard on the Nuvinci hub.

Interested in opinions, experiences. Anything would be appreciated.

Separately, a FYI tip. Do NOT buy a Staton gearbox without the available ~3/8" diameter high strength mounting pin. This is not well explained in his product descriptions - unusual for him. Took me 2 sheared pins to write Staton and get wised up. I even dug my 35 year old mechanics of materials text out of the basement and did the arithmetic from a free body diagram ('member them?). "Duhhh, that Dave Staton ain't so dumb after all....".
 

bigoilbob

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See your point, LR. 70% more torque, 60% more power, for less than 5# extra. I had thought about it, but was concerned about over twist on my NV171 hub. At 1.3 lb.*ft. of engine torque, 18.75/1 Staton gearbox reduction, a 13 tooth gearbox sprocket, and a 27 tooth hub sprocket, I am at ~51 lb*ft hub input torque. Doesn't account for losses, but they are not big when just starting the gearbox turning. The NV171 hub is rated for 48 lb*ft steady state hub input torque, and I am often close to that. But going from a 13 to about an 18 tooth gearbox sprocket would keep me "sort of" in the safe zone. A little harder on the clutch, but probably ok, as it now engages at less than 3 mph. Best part of your idea is no increase in moving parts.

Leaving for a couple of "post retirement" month on/month off rotations in Kurdistan as soon as the visa comes thru, and the lovely Ms. bigoilbob let's me keep some of those $ for blow money. Thanks 4 a great me gift idea!
 

Sidewinder Jerry

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Here is my current ratios. Gearbox 18.75, GB to shiftkit 18-44, SK to rear freewheel. 34 (34, 28, 24, 20, 16). I use a Robin Sabaru EHO 35 engine at 1.2 ft/lbs at 5000 rpm. So my current reductions are (45.83-21.57):1 at 55ft/lbs in low gear. When I upgrade this will be my ratios. GB-SK 22-44. I'll change the 18 gear to a 22. This will be my reductions (37.5-17.65):1 at 70 ft/lbs in low gear.

I use 26 inch wheels so that's why I need the lower reductions. In your case you have smaller wheels but much more weight. I'm just happy to see others building autoshift systems.
 

bigoilbob

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LR, since we're in the weeds with torques and such, I feel the need to brag about the one thing I have (and need to have), push. In addition to my input hub torque of ~50 ft.*lb, I have an additional starting reduction of 2/1 through the hub, giving me about 100 ft.*lb. Since my powered wheel rolling radius is a puny ~9.6", I get pushed at ~125# to start. Would be interested in others with comparable starting thrust.

Now, point well taken about weight, especially with 2 aboard. And I'm indeed a slow poke, maxing out at 19-20 m/h. Not even mentioning that my efficiency is 5-10% less than yours. All told, I like my bike, but your system is (1) way under appreciated, and (2) the wave of the future.
 
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