Nice Jackshaft Idea

Discussion in 'Performance Mods' started by motoredhobart, Mar 4, 2008.

  1. motoredhobart

    motoredhobart New Member

    I just came across this on the ZBOX site.
    I've been pondering a very similar idea for my bike for a while now. Been thinking about the same jack shaft setup and freewheel
    at the front but using an internal 3 speed hub at the back.
    This is just be the inspiration I needed!

    Pics are good..

  2. fetor56

    fetor56 Guest

    Fantastic idea and well executed.................too tough for me.
  3. Ghost0

    Ghost0 Guest

    I just finished doing the same mod on my bike. Well almost the same. Mine is a little more elegant and will be easy for all to do. I am looking into marketing it as a kit but I will share how to's. I am using a front freewheel with a standard 6 speed cassette on the rear. It is awesome to be able to shift. Will keep everyone posted. I have a few more tweaks to make before I publish.
  4. That's the thing though. Freewheel cranks are tough to come by. Unless you know of a source.
    That's truly a helper engine setup,helping you right at the crank.
  5. Torques

    Torques Guest

    I guess I don't get that system. Does it mean if you were under throttle and your feet slipped off the peddles, they would keep spinning on their own?
  6. The rear wheel would have fixed gears. No more freewheel. The freewheel is in the cranks. So the chain would always be moving. Always. When engine powers the bike the crank can stay still cause it's freewheeling.

    ...but then again,the rear doesen't HAVE to be fixed....right?
    The front DEFINETLY has to be freewheel though.

    (edit) rear sprockets have to be fixed so the Happy Time can be bump started
    Last edited by a moderator: Mar 4, 2008
  7. gone_fishin

    gone_fishin Guest

    good post, 'hobart

    good on ya! that's the MBc spirit that keeps us goin' :cool:

    edited out stoopid freewheel remark as stoopid.

    i've often wondered why i haven't seen any adaptations of this style...scroll down for freewheel crank parts:
  8. Hey all,

    Wow....Good find....I would love to be able to find a commercial jack shaft like what that bike has!....I would love to see a video of that bike running....Top end would be insane!....Acceleration should be good too.....Too neat!!

    Torques - In that setup it is the front 2 chain rings that can remain freewheeling while your pedals remain stationary.... When we were kids my sister had an old Sears bike set with a front freewheeling system....It looked like a regular 10 speed but could be shifted while coasting (the rear sprockets were not on a freewheel...all the sprockets were was the front chain rings that rotated while coasting with your feet on the pedals.....if you took your feet off the pedals the pedals should remain stationary unless the very slight friction of the front freewheeling pawls caused them to move a little--- which they often would with no weight on the pedals. Hope this is clear enough for you.

    Ghost - I am dying for some pics or a video too!!...Technology is definitely moving ahead here!

  9. Attached Files:

  10. sklein25

    sklein25 Guest

    I think I'm a little on the fence with Torques on this one?


    I see this as a helper engine that transfers power to the jack shaft and to the crank, to which the pedals and our feet are attached to. The way I see it, if you pedal and engage the engine and then twist the throttle. You will make the bike go faster and will feel less work for your legs. In fact if you lift your feet off the pedals, the crank will keep spinning under power as long as you keep twisting the throttle and using the power of the engine. It looks like you will have to get used to always pedaling when you engage the engine, unless you pull in the clutch and then be able to coast with the pedals in a stationary (9 o'clock- 3 o'clock) position.

    Maybe I'm just not seeing it here and a video would be a great tool to help describe the workings of a system such as this.

    In the meantime, here's a link to a Swiss company that has this electric assisted motor that can be engaged anytime you need the extra power for climbing up a steep hill or anything else:

    They have a few different versions available, but please check out their "Lanz V4 (Free Ride)" version that looks like it says "Version with a crank-free run for technically demanding terrain". Does this mean you can engage the motor and still not have to pedal? Cuz that would be great for very technical terrain where standing up on the pedals and balancing yourself would be very important and not having to worry about pedaling.

    Can anyone else shed some light about this type of system where attaching the motor or engine directly to the crank and then to the rear wheel.

  11. A freewheel crank means that the front sprocket spins INDEPENDENT of your crank. When you pedal foward THEN it catches the sprocket and you pedal as always.
    The chain is ALWAYS SPINNING for the rear wheel has FIXED SPROCKETS.
    If you're moving forward,you can pedal backwards to your heart's content.
    The front sprocket will be spinning with the bike.
    Last edited by a moderator: Mar 4, 2008
  12. sklein25

    sklein25 Guest

    The Swiss have beaten us!!!!!!!

    That answers my question exactly!!!! And I see that now in the design of the freewheel crank!!!! You can stop pedaling but still continue to run the engine as it delivers power through the crank, but not to your pedals. This is a great way to utilize the engine's power with the rear derailure and gears and still be able to free pedal your way around when needed!!!!

    Here's a pic of that freewheel crank (specially made by Shimano):

    And here is what the set up looks like mounted on a bike (electric motor-assisted):

    It looks like the Swiss have almost figured all this out already! Maybe they know a few things more than just how to make great swiss army knives!!!!!LOL

    Mind you this company is doing it with electric motors, but it can easily be experimented on with Happy Times engines!!!
    I'm currently waiting on email feedback from this company regarding pricing for the entire electric kit and just the freewheel crank assembly alone. They don't have any pricing on their site, but I'll fill everyone in on my findings. In the meantime, do check out their site, it's pretty cool all the stuff they do.

    Last edited by a moderator: Mar 5, 2008
  13. turkeyssr

    turkeyssr Guest

    This e-bay store is doing something similar: from Australia. You could ask if he would sell you just the adapter kit without the motor controller, motor, etc. His kits are too expensive for my tastes since they don't include a battery, but I do like the idea. -- John
  14. Isn't that shimano crank like over a hundred bucks? Boy if I had that,all I would need is a jackshaft and I would have...sniff..GEARS!
  15. motoredhobart

    motoredhobart New Member

    I saw those electric ebay kits too, emailed one of the sellers to see if they could sell me just the freewheel setup, 225+p&h...
    As for starting the engine wouldn't it be possible to just use the pedals kind of like the kick start on a motorbike? Assuming the jackshaft doesn't have any freewheels. But then If you just want to pedal the bike you'd still get resistance from the engine even when the clutch is engaged.
  16. Then get a pull starter and leave the rear wheel freewheel also.

    ...wait. Naw. When you pedal you still get resistance.
  17. Papasaun

    Papasaun Guest

  18. gone_fishin

    gone_fishin Guest

    that's what he sed :p

    yaknow, papa...i've posted links to these parts quite a few times and am suprised noone's tried any of it.
  19. Papasaun

    Papasaun Guest

    I would but,,, don't need em on my trike! :rolleyes::p:grin:

    I remember when you first posted that link, looked there and saved it but, moved on to my trike before I could use the info.

  20. Bolt on JACK

    This looks like a lot of potential... I like it a lot. Makes any frame have the ability for multi-speed with no frame mod. That is what these bikes need most. Buy it & assemble it on any 3 piece crank is what I'm reading. That is awesome.
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