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Discussion in 'Motorized Bicycle General Discussion' started by ferball, Jul 26, 2010.
Sounds realy good,simple. But I am with SB need to see how it works. Or a better explanation?
Its the same principle as a lawnmower, one fixed pulley and one you can change size. Or modern CVT used on modern scooters
It is done by having two separate sets of pulleys and two belts. A simple rocker mechanism tensions one set (lower gear) then when you move the shift lever halfway both belts are loose, then when you pull the lever all the way it tensions the other set (higher gears). It was seen on a lot of mini bikes and go karts in the 40-60 in Popular Mechanic, ect.
I think Bikeguy Joe is talking about something different? But anyway you are right I have one of them Verydrive pullys its all in one its a double pully were the center web moves back and forth as you move it to diffeent speeds. It would take up a lot of space It sure would be nice if some one could make one that would be a lot smaller and use the narrow auto motove belts insted of the wide B or 5/8's belts?
Thanks I think I remember seeing some thing like that. There again it would be nice if some of that would be down sized to run smaller belts.
With respect to the origional concept, if the parameters are 1. bolt on (i.e. no replacing hubs) 2. retain left hand drive. 3. shift on the fly is nice but NOT a requirement. 4. inexpensive and easy to install without special tools...well then, stacked gears would be the way to go, I rekon, but even then wouldn't you need to either spread out the rear tire mounts or get a narrower hub to make room for the new stack?....that S tensioner seems like a dandy idea, you'd need to mount that fairly far forward so you wouldn't have issues with chain alignment, right?
I am really enjoying this thread and am on pins and needles to see if someone can get the origional concept to work. Great to see a comunity like this working on an engineering problem collectively
AND sorry if this get's away from the origional concept but I origionally started following this thread because I liked the idea of a CVT (like the comet TAV 2) on a 2 stroke and was looking for some insight...so why don't I just ask...if spending the cash for it and doing a little "customization" wasn't a big issue, why couldn't I put on a torque-a-verter on a 2 stroke, looks like plenty of folks are doing that on 4 strokes, why not a china girl?
I know this topic is like 17 pages long now and this is a quote from like page 15 or something but I do have to chime in on the goats comment on Jackshafts...
No offense buddy, but the only loss of power to wheel I loose with J 3-speed hub shifter is my little stock 48cc motor trying to pull me sitting up in 3rd, but it will do me near 30MPH on a constant basis.
An expansion chamber tuned for speed would fix that too I imagine.
But my point is the same as it was in my post on like page 2 of this topic...
For the life of me I just can't understand wanting to gear a second drive train.
Don't tell me 'keeping the stock look' as an answer either, you are adding a motor and a second drive train!
Come on, please go back to basic math and logic.
I simply can not see any logic in either cost or logic to try to 'improve' an otherwise unwanted second drive train at all when you can simply use one with a Jackshaft!
Again I am sorry if I have offended anyone in this multi-page topic, and hey, best of luck, but I just can't see the logic especially when you start talking about adjustable tensioners on both sides!
I say if you have a vintage bike, put a 3-speed hub shifter and Jackshaft on it.
One chain, 3 gears, and about as stock looking as you can get with a motor.
I don't recall people talking about wanting 'that stock look' as a motivating force. You keep talking about cost when I don't see how you can compare a known with an unknown. So what is the cost of a jack shaft and three speed hub? That can be looked up and it isn't cheap. What is the cost of this proposed gear stack and shifter that hasn't even been worked out yet? No one knows. So how can you compare? You keep talking about logic, but this makes no sense. Saying something is logical doesn't make it so. And who is talking about adjustable tensioners on both sides. Both sides of what? The whole premise was to make a low cost shifter without having to buy a new wheel and internally geared hub along with a jackshaft kit. Would it be as good? I don't know. I know the SBP kit is awfully nice, also for a one speed cruiser is not cheap. Many of us just can't afford it. If your pockets are deep enough I think what you are suggesting is a real good way to go. Then there's the rest of us.
I have compared J shaft to straight drive. J shaft robs power. Take an air ratchet put a long extension on it , and what do you have? Put a cheap Harbor Freight impact socket straight off the air gun with a stubborn fastener. Put an old school Snap On socket on the same air gun it will get a move on.
While I have too J shaft bikes, because I love the gears. I beyond a shadow of a doubt I compromised power doing it.
I peddled way more in my life time than MB. A good stiff frame transferred the power more directly to the pavement. The bikes I had that swayed more under the cranks were slower bikes.
While gears are awesome direct transfer to the pavement wins hands down. My buddies with direct drive have quicker bikes. Why is that? This could be compared to stock China motors all day long.
You can run a shift kit to a mathematical match to a side by side comparison of a fixed rear gear. While all the chains, brackets bearings etc are rattling away the direct drive will be further down the road.
Now some one will say but with my gears I can make up for that.
It does not change simple physics. While I run two J shaft creations and love them. I loath for the day I could keep my gears and have just one chain!
If That Flipped Over 3 Speed Internal Hub That Was Posted About Would Work On The Left With A Large Sprocket Of Proper Size Bolted To It. Then Thread The Brake Arm Side For A Rh Freewheel Sprocket For Pedal Side.
Hope Someone Can Post Pic`s Of The 3 Speed Hub Flipped For Left Side Drive.
It Seems To Good To Be True.
Is A Anchored Brake Arm Needed For The Internal Shifting??
Oh, Now I Remember A Thought I Had The Other Day. With the 3 speed flipped over, Mount A Pedal Sprocket Solidly To The Rear Hub And Use A Free On The Pedal Crank.
Just Some Thoughts.
Jim = Mm Has A Big Challenge On His Hands. Hoping He An Get It Done.
I don't mean to be an a$$, because I get what you are saying completely, but "loath" means hate. You "long" for the day....
Nah...A simple 3 sprocket shifter on the drive side is no problem...a mirror image, (functionally), of a 3-speed internal hub...BIG PROBLEM!
My Desk Top Dictionary And Spell Check Has Help Me Hide All The Days That I Slept Thru English Class`s. They Have Saved Me From Many Worse Abuse`s! Lol
I Am With You Getting It Done!! Would Be A Durable Option.
From Owning, Maintaining And Operating My Stump Grinders For 30 Years "durable" Is Number One.
Just Like Racing! The Race Is Won In The Shop. We See That With Nascar, Too Much Lately!
Your Only As Good As What You Are Sitting. A Statement By Ernie Derr A Long Time Ago.
I Hope I Have Redeemed My "own" Self!! Dum & Dummer.
Please put this one in the Snork Thread.
Sorry Ron, human error!
Nope I was being sarcastic and cynical. From my point of view. Something else to fear and loath the design. Time for me to get a Motorcycle. Why is there not a left side geared drive out there
I am already studying the N.V. wondering why it was never designed with a left side drive. Now someone will miss that too!
I mean the cog driving by the motor with the N.V.'s internal gearing working with the sprocket connected to the motor. That would mean no J Shaft and one chain to rule them all!
what about the pedals and chain on the right?
What about them? Look through all the links painfully and the alternatives to the right side will present them selves. Simply put a sprocket on the right side. They make free wheels to go on the cranks etc. We are already putting a rag joint together with multiple sprockets. There are top hat adapters, disk break mounts. I don't get what you mean that's the easiest hurdle to do ever compared to a a geared hub? What do you mean?
What is so hard to understand about the s3x fixed gear 3-speed?