A new shift concept for the engineers....

Discussion in 'Motorized Bicycle General Discussion' started by ferball, Jul 26, 2010.

  1. ferball

    ferball New Member

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    Crazy idea for some of the shop guys out there. I lack the facilities and the know how to even begin to fabricate this idea. Why not make a shift kit for the 44t sprocket? Bolt a 36t and a 56 or 60t to either side of the 44t and simple derailer. Suddenly a 1 Speed cruiser bike has options, plus the derailer would take care of the dreaded "tensioner" question. It is only 3 speeds but if you could work it out it would be a neat alternative to the jack shaft shift kits. Plus who ever figures it out could sell the "derailer" as a very nice chain tensioner alternative. Heck even two speeds would be cool. I know there some obvious up front problems like axle width and stuff but I bet it could be done.

    All ask is in exchange for this million dollar idea is that it be called the Ferball Shift Kit, and I you send me one.
     
  2. Creative Engineering

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    Can we compromise and call it the "Fireball shift kit" :D

    Jim
     
  3. professor

    professor New Member

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    The problem with the HT kits for this idea is that it lacks a freewheel to accomidate the derailer.
    The bike derailer works because there is force only in one direction.
    If there was an intermediate shaft with a freewheel on it - it would work- IF there was enough room back by the wheel to fit 2 more sprockets.
     
  4. silverbear

    silverbear The Boy Who Never Grew Up

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    Even a two speed would be great... something for low speed and hill climbing and the higher gear for normal cruising. Wouldn't that be great! Come on Jim, I'm ready to place an order.
    SB
     
  5. Creative Engineering

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    It's doable...:D I'm more concerned about the outcome "cost-wise" than the technicalities of making it work.

    I don't think a deraileur will make a large jump, (2-speed); although you're right SB 2-speeds would work just fine...I just finished modeling up a 44, 40, 36, scenario, and I think that would work fine.

    The main thing is that the chain is going to need to be fairly taught on the 44T for starting. In other words the deraileur/chain length will have to be adjusted so that there is very little spring action in the deraileur.

    If the engine shut-off while riding on the 36T...it would be a problem as you would then be at full deraileur travel...i.e. a lot of potential slack on the bottom chain run. This could prove to be an annoying aspect of the set-up if the rider were not paying attention to gear selection before shut-off.

    The system works, conventionally, when pedaled in forward motion...so I don't see a freewheel being critical to operation.

    A sprocket adapter, with a 3-stack of 410 size sprockets, and a deraileur adapter should do it. This is, off course, over simplified as there would undoubtedly be a lot of adjustments to be made to get it to work just right.

    I might try it...It should only take 2 days to prototype...now where am I going to find 2 days of free time. laff

    Jim
     

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  6. BarelyAWake

    BarelyAWake New Member

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    Perhaps I've just not noticed bfore... but are left side rear derailleurs common/available? I don't see how ya could use a right hand one on the left side...

    Enlighten me plox :D
     
  7. ferball

    ferball New Member

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    We can call it the Fireball... I guess.

    As far as the free wheel goes I never ride in reverse so I don't think that would be a problem. You could also offer different gear set ups, because I would want something with a larger sprocket for hauling fat guys up hill, as opposed to trying to break the sound barrier.

    As far as as a 410 size goes that should still work for those of us that run a 415 as long as that is taken into consideration, because the pitch is the same just a bit wider right?
     
  8. Goat Herder

    Goat Herder Gutter Rider

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    A 410 is the same pitch its narrower. It is the ultra tough BMX chain.
     
  9. ferball

    ferball New Member

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    Left side derailer would need to be engineered to accomodate the beefier chain, I would think. Or just modify an existing one, but I don't think there is one out there, because if there was we would see them used as a tensioner alternative.
     
  10. silverbear

    silverbear The Boy Who Never Grew Up

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    If chain tension with start up is a problem, even if this is only practical with a pull start motor, that's fine with me.
    SB
     
  11. bairdco

    bairdco a guy who makes cool bikes

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    here's a couple of things to consider;

    steel sprockets would have to be used. because of the drag of the chain when switching from gear to gear, it would destroy an aluminum sprocket in a matter of days.

    the average bicycle will not accomodate 3 sprockets on the rear. a 410 chain is almost 1/2" wide, and you need space between the sprockets for it to ride on. probably at least 2.5 - 3 inches on the left side.

    the major force of the chain is on the top as it's pulled into the motor. while a derailler could work to shift the chain, it won't do anything to help the alignment. with three sprockets, the center one would have to be aligned with the motor, and the other two would be offset. this could potentially cause the chain to come off the side sprockets. also, if the center one was aligned, there wouldn't be enough room on the inside for another sprocket unless the motor was offset.

    as cool as having gears would be, trying to adapt conventional bicycle gearing doesn't sound feasable to me. one good shift from 2nd to 3rd at 45 mph would probably rip the derailleur to shreds.

    what i'd be interested in would be making a left side drive internally geared flip flop hub.
     
  12. Creative Engineering

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    Baird,

    I would use #410 heavy duty bicycle chain, not the typical kit supplied 415 chain. A three sprocket stack is actually quite narrow...diagram below.

    In addition to the fact that the sprockets need to be steel...the sprocket teeth on a standard cluster are slightly twisted. I'm sure this is done to ease the chain onto the next larger diameter sprocket when downshifting. Although not impossible to do here at the shop, I really don't want to make a special tool for an experiment. I'll try it with straight tooth sprockets.

    I don't see any problems with alignment; but as you pointed out the deraileur may fly apart!

    We'll see what happens.

    Jim
     

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  13. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    A multi speed bike chain is also made for the gear set/derailuer, the #410 #415 ect are not.

    But you knew that.
     
  14. ferball

    ferball New Member

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    I don't think alignment would be to big a problem, my bike is not realy close as far as that goes and it works fine. Even if the shifting was like the old school 4x4 when you had to stop the vehicle, get out and engage the hubs. I mean if you had to stop the bike and kick a lever to change the sprocket it would still be nice to have that versatility. Cruise around on a 44t and kick it to a 52 to go off road, or kick it to a 36 for some nice flat cruising.
     
  15. Creative Engineering

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    No...I didn't.

    I looked it up, and it looks to me like this chain works together with the twist in the teeth for a smooth engagement...especially at a low chain speed.

    The department store bikes I've seen do not use this special chain.

    Jim
     
  16. Maxvision

    Maxvision New Member

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    Gawd I LOVE it! Creative minds at work.... .cptr.
     
  17. K-dregg

    K-dregg New Member

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    Interresting concept.. As i see it the weak link is the derrailure, even the beefiest ones are weak so to speak and it wouldnt hold up for the forces generated from the engine.. Another thing is that when you shift gears on a bicycle the derraliure operates better if you dont load the pedals, you ease of a bit until the chain pops in place.. Try to shift gears while peadling up a steep hill and you'll notice the difference. So shifting under power could be problematic..
    And to my knowing there are no left side mounted derrailures, scratch build maybe?
     
  18. silverbear

    silverbear The Boy Who Never Grew Up

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    I've got my fingers crossed that this is going to work, you guys. I have admired the SBP shift kit for some time and think it is perfect for a multi speed bike with a derailleur. When I saw BarelyAWakes Rollfast build I was so enamored of what he had done... it just seemed to lift motorbicycling to another level. Where I live both here in Minnesota in the summer and in the mountains of northwestern Maryland in the winter it is hilly. With a coaster brake one speed there are places I can not ride without getting off and walking the bike. What a difference it would make to be able to shift to another gear and as Ferball said, if I had to stop the bike to change the gearing then I could live with that. It would be lots better on the fly of course, but it would make an old cruiser so much more versatile. And not just old cruisers, but say a Worksman which is the same thing but more recently made. Barely went through some money, time and careful fitting to make the SBP kit work on his vintage cruiser. It can be done, but not without dedication and kind of deep pockets. If you can make this setup work with a coaster brake un geared hub it will make solid old cruisers much more appealing to a wider range of riders. More guys would be riding on strong foundations.
    Unlike Bairdco, I have no concern about something flying apart at 45 mph. I'd
    never go that fast unless I went over the edge of a cliff. I promise that if you can make this work I'll baby it and kiss it into the next gear, never going over 30, never abusing it. I'm following this thread really closely.
    SB
     
  19. Goat Herder

    Goat Herder Gutter Rider

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    If a 410 chain had a cleverly designed derailleur it could work. Well maybe? Me thinks only two gears at best. Problem being will be folks not paying attention to a proper way to shift it.

    As a kid I would take a BMX chain and make it work with a front derailleur by widening it to make it fit as well as a back derailleur for a said now needed tensioner [only]. Now I am not talking about a rear set of cogs spacing will never work.

    It would be nearly impossible to see folks not tear it up on a motor as shifting will have to be done at a lower speed than the given load. I do think it can be done in that respect.

    As for the teeth and the cog sets gently cut out slopes that raise the chain into the bigger gear not bent teeth.
     
  20. Goat Herder

    Goat Herder Gutter Rider

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    On the note of chains and gracefully moving around sprockets. The SBP shift kit has proven what a standard derailleur bike chain can do!
     

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