OY! Florida! OY! Sprockets!

Discussion in 'Motorized Bicycle General Discussion' started by xetaprime, Sep 2, 2011.

  1. xetaprime

    xetaprime New Member

    Joined:
    Aug 31, 2011
    Messages:
    47
    Likes Received:
    0
    Last night I was so excited about jumping on the MB bandwagon until this morning reading all about Florida's motorized bike laws AHHHH!!! One good thing is I have a motorcycle licence. Maybe that will help me 'when' I get stopped. IDK. I hate these laws!

    Sercondly, question, I have this flip flop hub on my new bike and I'd really like to use it. I have not read of anyone using a 22 tooth sprocket. What would happen? I'm not necessarily looking for speed. 20mph would be fine with me even though I ordered an 80cc engine. going 20 here might help with the fuzz also since electrics are legal at 20...

    Would the problem be starting it? What if I added on a second free rolling sprocket below making the chain extend? Would that change torque/whatever? Yeah, I have no clue here ;)

    My need for this machine is to get me to the market that is too far away for peddlin' at least when I don't want to pedal. Is there a norm calculation for teeth vs speed I can look at? Still have a week to 10 days before engine arrives so whether I mount the stock sprocket or not it's up in the air.

    Best, Xeta
     
  2. decoherence

    decoherence New Member

    Joined:
    Aug 23, 2010
    Messages:
    476
    Likes Received:
    0
    the smaller the sprocket is made for higher speeds. the opposite of 20mph. not even sure if a china girl can even make enough torque for a 22 tooth.
    if you want to only do 20mph then you are looking for a large sprocket. like 40t.
     
  3. xetaprime

    xetaprime New Member

    Joined:
    Aug 31, 2011
    Messages:
    47
    Likes Received:
    0
    Thanx dc. I wish they made a 40T fixed cog.

    Hey, but if I did drop another cog below it on a fixed plate would that change the torque a la a larger single sprocket?

    Something similar to this but not this- assuming the front is the enginge drive sproket?

    [​IMG]
     
    #3 xetaprime, Sep 2, 2011
    Last edited: Sep 2, 2011
  4. decoherence

    decoherence New Member

    Joined:
    Aug 23, 2010
    Messages:
    476
    Likes Received:
    0
    nope. it doesn't change the ratio of the final gear.
    there might be a sprocket or an application that will get a larger sprocket on a flip flop hub.
    i don't have one so i never checked.
    i know on my coaster brake hum i changed out my 20T for a 22t.
    it gave a 10% more starting power but i cant "help" my engine when going by peddling.

    you can get a shift kit. it brings the engine power to the other side of your tire and will let you use smaller sprockets because the way it is geared.
     
  5. xetaprime

    xetaprime New Member

    Joined:
    Aug 31, 2011
    Messages:
    47
    Likes Received:
    0
    What if I used this 22 tooth fixed cog with the stock 80cc sprocket and used the holes on the cog for fastening???

    [​IMG]
     
  6. decoherence

    decoherence New Member

    Joined:
    Aug 23, 2010
    Messages:
    476
    Likes Received:
    0
    if you can get a sure fit & make sure that it stays that way it is a possibility. it just needs to have no wobble from side to side & be perfectly centered.
     
  7. Nashville Kat

    Nashville Kat Active Member

    Joined:
    Apr 20, 2009
    Messages:
    1,442
    Likes Received:
    6
    Yes the 22 would be too big of a gear-

    plus- unless you secured it to the flip/flop with the holes in the cog- it would tend to unscrew under backpressure- that's why there's a lockring on the outside of a track bike cog-,

    I've searched before for track cogs but 22 is about the biggest- if someone made a 34 0r 36 or larger, we'd be in business, and could hold it in place with a lockring on a track hub

    Most flip flops these days are coming 32, but 36 spokes aren't rare- the more the better, but I still don't want to jump up to 48 spokes

    I have a 41 cog bolted directly to a flip/flop I drilled- but you need a large flange preferably not already drilled- out there but hard to find a bit

    here's thread and pictures I posted before
    http://motorbicycling.com/f15/sprocket-bolted-drilled-flip-flop-24770.html
     
    #7 Nashville Kat, Sep 2, 2011
    Last edited: Sep 2, 2011
  8. xetaprime

    xetaprime New Member

    Joined:
    Aug 31, 2011
    Messages:
    47
    Likes Received:
    0
    Thanx, I was looking at large flange hubs today. Guess I'll wait till I can hold the 40t to the bike to go forward. If I could attach the sprocket to the inside of the 22t cog and use the lock nut it could work... dunn duhnn duh.... :) Just trying to avoid attaching it to the spokes- if I can.
     
  9. xetaprime

    xetaprime New Member

    Joined:
    Aug 31, 2011
    Messages:
    47
    Likes Received:
    0
    I'm still buggin' so forgive trying to go further with this.

    Wouldn't adding that extra pully sprocket in the rear, expanding chain length, making it wider in the back, slow down rotation? The above picture is an early derailleur invention meant to change speeds... the more chain the slower the wheel turns, no? More distance the chain point A (drive shaft) has to return to point A, no? If not why?

    Oh, and good mornin' to y'all :)
     
  10. decoherence

    decoherence New Member

    Joined:
    Aug 23, 2010
    Messages:
    476
    Likes Received:
    0
    no. it isn't the length of the chain that changes the ratio.
    the derailer is to move the chain when there is more than one gear.
    look at the chain. each tooth goes into each link.
    now look at the chain @ the top of the gears.
    they are directly connected.
    if you notice many of our bikes use an idler pullry. (some even use a gear.)
    it doesn't change the ratio one iota.
     
  11. xetaprime

    xetaprime New Member

    Joined:
    Aug 31, 2011
    Messages:
    47
    Likes Received:
    0
    Thanx for the explanation. Yeah, I did wonder about the pulley. It's all good. I have a new plan :0 anyway :)

    Best,
    Xeta
     
  12. CTripps

    CTripps Active Member

    Joined:
    Aug 22, 2011
    Messages:
    1,311
    Likes Received:
    0
    My wife's 80cc is set up with a 48T sprocket, and it idles at 33kph/20mph when warmed up. That's on a 26" wheel. A 24" wheel would be a little slower.
     
  13. xetaprime

    xetaprime New Member

    Joined:
    Aug 31, 2011
    Messages:
    47
    Likes Received:
    0
    I've read here that larger sprockets 'may' cause more vibration. Maybe I could just go with the stock 40T and limit the throttle with a stop of some kind? I'm a major tweaker. I love to tweak. I dream tweak :) I can't fraking wait for that fraking engine!!!!! This week I hope. Truth is right now, I just want to mount that engine. That didn't sound right ;)
     
  14. DuctTapedGoat

    DuctTapedGoat Active Member

    Joined:
    Dec 20, 2010
    Messages:
    1,179
    Likes Received:
    8
    You don't be able to use a flip flop hub for the sprocket mount.
     
  15. xetaprime

    xetaprime New Member

    Joined:
    Aug 31, 2011
    Messages:
    47
    Likes Received:
    0
    I think I've found a way by locking the lockring. Maybe. But I'll know more once the engine arrives.
     

Share This Page