Jackshaft Jackshaft research

Discussion in 'Transmission / Drivetrain' started by Rob_E_Rob, Nov 10, 2009.

  1. Rob_E_Rob

    Rob_E_Rob Member

    A jackshaft like the one SBP sells looks really cool. I am sure they work pretty well, but it also looks like it could tear your leg up if something went wrong. Does anyone have any input on a jackshaft? I am trying to figure out if it's worth it.



  2. super dave

    super dave Member

    i have one on my bike and works very well. i used this kit because i have front and rear disc brake, so in order to keep the rear brakes. all is good with this kit for me. the only think i don't like is it is a little hard to start but not a big deal once you get use to it. easy to install just take your time.
  3. Were can I get one

    Were can I get one and how much did it cost????
  4. Fabian

    Fabian Well-Known Member

    Hi Rob E Rob

    I'm glad you've made the wise decision to look into getting a Shift kit.
    Some 5 months ago, my personal circumstances changed, requiring the need for a motorised pushbike.
    After a lot of research, the sensible option was the SickBikeParts Shift kit - they were the only people with a professionally made system capable of doing the job.
    A single speed drive method is a complete waste of time.

    I have had no problems with the shift kit itself but in the beginning had a lot of problems with the original bicycle chain drive to the rear wheel with serious chain suck issues when in 1st gear (chain closest to the spokes) on bumpy dirt tracks; chain bouncing around like crazy.
    The issue never raised it head riding around town on bitumen roads.

    These problems were fixed by strategic placement of the original idler wheels supplied in the Chinese motorised bicycle kit, fitting them close the the chain wheel, eliminating chain bounce as the chain engaged the chainwheel teeth.
    I've not had one singe problem with chain suck since doing the modification.

    Although not necessary, i've made a chain tensioner for the chainwheel to jackshaft chain.
    It just means you never have to adjust the chain tension after installing the kit.

    Follow this link and you'll see my concept for idler wheels and chain tensioner.


    Cheers Fabian
    Last edited: Nov 11, 2009
  5. super dave

    super dave Member

  6. give me vtec

    give me vtec Active Member

    the sick bikes kit comes with a chain gaurd if you want to install it... most people just choose not to. I have one on my red baron, no problems yet.
  7. Thanks for the link,but I was thinking some other company was making them now....I was half awake when I read this post,my bad....
  8. Rob_E_Rob

    Rob_E_Rob Member


    I gotta tell you that is one cool tensioner, but how come you need it? Was the chain loose? I just wonder if having all that around your leg is dangerous?

  9. SuperDave,I have your bike as my computer screen background....That is one bad to the bone bike....I seen felt has them priced around 1500....Man I wish I had the money for one of those....
  10. Fabian

    Fabian Well-Known Member

    Chain stretches the most when new, so for the first 200 kilometers, you'll have to readjust the chain tension a couple of times.
    After that, it settles down and you'll need to readjust every 400 kilometers.

    It's no big deal. Takes less that 2 minutes.
    My situation is a bit different as i'm towing heavy loads; putting significantly more strain through the shift kit and chains.

    In my application, a base grade Shimano HG-53 9 speed chain lasts 1000 kilometers before breaking in half - an amazing distance considering it's small size and light weight.
    Surprisingly, i breaks from fatigue, not wear.
    Up until breakage, the chain is within stretch specifications of 0.5%.
    Just incredible how well made and durable these chains have come to be.

    The shift kit comes with protective covers for the jackshaft output sprocket so you can't get anything caught in the chain drive mechanism.
    I don't use the protective covers, preferring the exposed gear and chain "look" - chains and gears spinning around are captivating to watch.
    To prevent my jeans going anywhere they shouldn't, i use bicycle leg clips, stopping the leg end flopping about and getting caught in the system, if not using the supplied protective covers.

    Photos of my bike and trailer setup in the links- best explains how much load and stress is going through the SickBikeParts shift kit and chains.
    One word of advise - get the "Deluxe Shift Kit" as it comes with the rebuildable heavy duty crank bearing and tool assortment and some quality extras.



    Cheers Fabian
    Last edited: Nov 12, 2009
  11. Alaskavan

    Alaskavan Guest

    KMC xtreme (free style) chain works really good.
  12. 210061741

    210061741 Guest

    Nice taco post Fabian

    I like it.

    Someday i'll finish my jackshaft design.
    No $$ and little time right now.