A new shift concept for the engineers....

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

  1. BarelyAWake

    BarelyAWake New Member

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    Not disparaging a different method of having gears, the lack of a jackshaft is in some ways attractive for it's simplicity, even redundancy (bust & loose a chain = still get home w/o walkin') - but I do gotta point out that SBP's prices are not "out of line", the basic kit costs $144 and I just priced out the components yesterday to help with a friend's DIY jackshaft project and it's perilously close to $100 already... still tryin' to find a workaround fer that lol - he's jus' a kid and his allowance doesn't stretch that far... prolly gonna copy Russell's http://motorbicycling.com/f3/combined-mtr-mount-jack-shaft-21463.html

    Just saying ;)
     
    #61 BarelyAWake, Jul 30, 2010
    Last edited: Jul 30, 2010
  2. silverbear

    silverbear The Boy Who Never Grew Up

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    Curtis,
    Without a very thorough understanding of all this, I would imagine that three sprockets, the axle adapter and derailleur bracket would still cost some bucks to produce. I think the SBP kit is elegant and is tried and proven. And while it isn't cheap to buy, it also isn't cheaply made, with manufacturing of the kit coming from the good old USA. For what it does for a bike which is already geared I think it is reasonable. What starts to jack the price of going that route is with a bike which does not already have external gears. For someone like me who always ends up building a cruiser with no gears and a coaster brake, the cost of converting to an internally geared axle strong enough to withstand the forces generated by an engine is beyond my meager pocketbook. I looked in to what Barely did with his Rollfast and it is a wonderful setup, but there was nothing quick and easy nor inexpensive about it, further made difficult by his wanting a wheel with heavy duty spokes. Also, the axle could not have a coaster brake as a freewheel hub is necessary. Even if I had the funds, I don't know that I could do it as Barely's mechanical skills are much greater than mine. What I see as the beauty of this little sprocket cluster approach is that it makes gearing a cruiser a more straightforward endeavor and with a only kit to buy should make converting a coaster brake cruiser a relatively inexpensive modification... the key word being "relative". Having different kits available for different kinds of bikes is a good thing, as I see it. If I understand correctly how these sprockets mount, the hub adapter is necessary and that is now being made for only select standard axles. So it may be that you would need to have an axle appropriate for the adapter. For me that it not a great problem since I have been swapping out the original tired old wheel I find on vintage bikes for a heavy duty wheel with thick spokes, but still a single speed coaster brake as original. Heavy duty wheels is something I do anyway and Jim's sprocket adapter is also something I started using with the Elgin build last winter. There was such an improvement over the old rag joint that I'll never go back. So for me I already have the right wheel just asking for the sprocket cluster now being made.
    SB
     
  3. ferball

    ferball New Member

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    As far as the aluminum cluster goes, I would think that if the spacer was close to the diameter of the sprocket, the layering would help keep things from flexing and bending.
     
  4. Creative Engineering

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    I'm thinking the same thing...for the steel ones I'm just going to space them with ground washers, (standard washers placed on a surface grinder and ground perfectly uiniform and flat).

    For the Aluminum cluster, full circle rings could be made that should eliminate flex.

    I love experiments...:D

    Jim
     
  5. Ghost0

    Ghost0 New Member

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    Like the patent guy said, "everything has already been invented". Attached are pics of my first attempt at gearing a motorized bike. I too felt this was going to be a simple solution but it turned out not to be the case. Going with a derailleur on the left or right causes problems with a fixed rear sprocket and the want to bump start. But maybe you all can find better solutions to the problem than I was able to come up with.
     

    Attached Files:

  6. Creative Engineering

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    Whoever made those sprockets didn't realize that the 10-11 degree bevel at the teeth is critical.

    The chain plates will snag if there is even the slightest bit of mis-alignment.

    Jim
     
  7. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    I think the way Camlifter used a internal gear hub on the drive chain for his 'Biker build off' bike is the only way this is going to happen. ;)
     
  8. curtisfox

    curtisfox Well-Known Member

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    I was implying that if they pay that much for SBP the new one should sell I for one am intrested. Like you sit back and change gears when (Going gets tough the oldtough get going.)
     
  9. silverbear

    silverbear The Boy Who Never Grew Up

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    GhostO said, "Going with a derailleur on the left or right causes problems with a fixed rear sprocket and the want to bump start "
    What if the engine had a pull start? That would ease things up a good bit on the sprockets and chain. I'm planning to install a pull start kit on the PK-80 anyway.
    Curtis,
    Yeah, wouldn't that be great at the bottom of hill to shift it down and climb right up to the top with no pedaling til your pants catch on fire, no tongue hanging out and no heart attack. I'm ready.
    SB
     
  10. curtisfox

    curtisfox Well-Known Member

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    AMEN!!
    Nothing spoiles a old farts good ride like have to get off and push or pedal up hill
     
  11. NEAT TIMES

    NEAT TIMES New Member

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    Jim

    Would It Be Possible To Reverse The Spring Force Direction On The Derailer Spring Tension Arm ?

    As You Know, The Cable Pulls The Arm To And Away From The Wheel, For Chain Alignment. The Main Problem Is The Derailer Bicycle Chain Tension Arm, Swinging the wrong way.

    When You Flop A Freewheel Over It Reverse`s. Would The Coil Spring Do The Same? Think About It Till You Get A Headache, Then Post!! Lol.

    Maybe Stock Rear Derailers Could Be Modified To Swing The Chain Tension Arm The Other Way, For Left Side Use.

    I Think You Can Do It. Imho, The Derailer Is The Big Problem .

    All You Need Is A Spring Making Machine ! Lol.

    Thanks For Tackling This Endeavor!

    "We Must Endeavor To Persevere" (Josey Wales = Indian)

    Ron .cvlt1
     
    #71 NEAT TIMES, Jul 30, 2010
    Last edited: Jul 30, 2010
  12. Creative Engineering

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    Ron,

    I watched that movie just a few nights ago...Outlaw Josey Wales...Clint Eastwood. It was on one of the movie channels. I remember seeing it years ago in the theater.

    Utilizing a standard deraileur may end up posing a problem...don't know yet. If I have to make something that will allow the chain to float from one sprocket to another; I will.

    I like to get one thing at a time out of the way, and then move on to the next. Once the cluster is mounted to the wheel, and the chain run from the engine to the second sprocket is aligned; I'll look at a shifter mechanism.

    It's easier this way...to work with the known...and not let the "how" confuse things too early into the process.

    Jim
     
  13. Goat Herder

    Goat Herder Gutter Rider

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    Make us a simple click shifter that runs one of the BMX variety of chains. This would be for the j shaft approach. One could then run 4 or five cogs spaced out to accommodate wider chain where there cassette is on the right side.That would be good for some of us running higher powered engines.

    Sorta the same approach for a click shifter you will be making for the left side? Its a thought
     
  14. Goat Herder

    Goat Herder Gutter Rider

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    Then again the old penny shifters on the bars [could re tighten with a penny] Had numbers on it to sorta tell where ya were. Rapid Fire shifter is the best handler bar shifter I ever liked

    To use today's clique shifter you gotta have a one to one action derailleur.
     
  15. Creative Engineering

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    That's a good idea GH!

    I wouldn't want to venture down that road myself as SBP already has experience with this arrangement.

    Jim
     
  16. ferball

    ferball New Member

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    suicide shifter on the top tube would be awesome.
     
  17. silverbear

    silverbear The Boy Who Never Grew Up

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    I plan to use an old throttle type shifter from the sixties that was for a 3 speed English bike. Should work OK.
    SB
     
  18. Creative Engineering

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    I'm looking back through some of the other comments...

    I can't for the life of me understand what possible difference a freewheel action could have on the gear selector. The cluster has to be in forward motion in order for the chain to make the transition up or down from one sprocket to another.

    You don't pedal backwards to change gears on the right side?

    Obviously a freewheel is a nice design feature when the chain is attached to pedals...but when attached to an engine; I just don't get the need for a freewheel.

    Jim
     
  19. bairdco

    bairdco a guy who makes cool bikes

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    i was thinking about that, too. with a freewheel you'd need to pull start it.

    the main reasons for a freewheel are to set up your pedals for corners, stops, etc, and with multi-geared bikes, deraileurs don't work when pedaling backwards, so they don't work with a coaster brake.

    weight is another reason. internally geared hubs and coasters weigh a lot more than what's essentially a front hub with a gear(s) screwed on.

    it would be awesome to have a freewheel for coasting down hills, so your chain's not slapping around, but if i had gears, i wouldn't need to coast down hills...
     
  20. NEAT TIMES

    NEAT TIMES New Member

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    Jim

    As You Sort Of Say; It Would Shift Easier With The Direct Drive Hub.

    On My Shifter Bike I Need To Give It Gas To Down Shift, Because Of The Freewheel Cassette And The Freewheel And The Pedal Crank, To Make The Chain Turn.

    When Gaining Speed And Up Shifting, I Let Off the Throttle For A Second, Or It Will Slam Into The Next Gear When Taking Up The Chain Slack From Going To A Smaller Cog.

    Looked At A New 5 Speed Cassette I Recently Bought On Ebay. It Has The 38 Tooth Starting Cog. (then I Can Use A Larger Tooth Count On The Bottom Bracketchain Ring = Drives Rear Wheel).

    The Teeth On The Cassette Are All Straight, No Twist Or Angle On The Teeth.

    Jim, Thanks Again For Your "endeavor`s To Persevere" !! Your Congregation Faithfully Applauds You.

    Ronnie
     

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