Best gear for speed 24inch tire

Discussion in 'Performance Mods' started by NARLEY PEDALSON, Oct 13, 2011.



    I am putting togetter a happy time kit on a 24inch bike and i want to cruise at a low rpm at desent speed and be able to try for 50mph on those emtpy dark roads at night

    the engeine will be blueprinted from the get go so it will have a bit more then stock power to turn a lower geared set up

    so what would be the best T rear sprocket for my bike

  2. max350

    max350 Member

    Which engine? a china engine can not run 50mph with just a blueprint!
    Last edited: Oct 14, 2011
  3. motorpsycho

    motorpsycho Active Member

    if you gear it lower,l you will get more bottom end torque, not top speed.
    If you want top speed ypu need to gear it higher (smaller rear sprocket)
    a 36 tooth woudl give you some pretty decent top speed, but your take off power will suffer.
    a 36 tooth may get you close to 40 mph (MAYBE ON A GOOD DAY), but it may take a long time to get there. think of taking off in a car from a dead stop with a manual transmission in 3rd gear. sure, it'll go but you have to feather the clutch, rev the engine and it will take awhile before the car will get up to speed.

    you can get smaller than 36 tooth rear sprockets but they are expensive.
    the smaller the rear sprocket, the more top speed / less bottom end power you will get.
    the bigger the rear sprocket, the more bottom end take off power / less top speed you will get.

    if you want to TRY to get to 50 mph with a china engine, you will need to port and polish the head, shave the head for more compression, add a hi-perf carb, high flow air filter, expansion chamber, better plug and plug wire and a shift kit with at least a 7 speed rear hub.
  4. Neon

    Neon Member

    I agree with you there, but it has to be a megadrive cassette or something along that line. The standard rear cassette gear spread has not changed since the 5 speed. The tooth count has been 28t-14t for years, at least any that i have run across. They fiddled with the in between gears to get the extra speeds. So it doesn't matter if it's a 5,6 or 7 the end result will be the same.
    Might consider larger wheels instead of the 24. Even 26 would be better for top speed than 24. But again acceleration will suffer slightly. What happened to the CR85 project?


    well um in testing the rear driver broke so i replaced the whole weel set then i was driving across grass and tryed the to rip a roster tail but found a geat way of de spoking a rime by dropping the cluch in 2ed gear so new rim again but this time from the garbage and i cold not get the chain to say on whats so ever and it took me about 10days to figer out that the frame was out of true

    all in all it was a ton of fun for maybe 2 miles and i never toped her out


    please answer this at least

    sorry its a 25inch tire so its not normal

    anyways with what rear spocket chould i use to do 50mph if my engine had the power to crank over that kind of gearing
  7. Neon

    Neon Member

    Use jpilots gear ratio calculator and figure it out for yourself. It's a sticky near the top of this thread "Wild In The Streets" that is.
    Last edited: Oct 18, 2011
  8. Easy Rider

    Easy Rider New Member

    Here's my bike with 24" tires. I ran a 52 tooth rear sprocket at the Grange race and I was radared at 41mph.

    Attached Files:

  9. 5-7HEAVEN

    5-7HEAVEN Active Member

    The boy is asking advice about a Happy time's performance w/a 24" tire, not a Morini.
  10. Easy Rider

    Easy Rider New Member

    Well since your the resident "know it all" I mean "expert", throw in your two cents. People usually use a smaller tire for low end reasons. More pop off the line or coming out of the corners. A HT motor using a 24" tire and if he wants to hit 50mph probably can't be done. Your closest bet would be using a SBP shift kit. The problem is the lack of power to maintain the speed unless you're going downhill.
  11. 5-7HEAVEN

    5-7HEAVEN Active Member

    Lol, I'm not the resident know it all, you are.

    Lookit my bike w/Morini. See how fast my bike goes on someone else's thread.

  12. Easy Rider

    Easy Rider New Member

    Ohh find another thread I put my bike in beside here.
    I don't make false facts like your so called super fast "cough cough" bike. Which we all know doesn't reach the speeds you claim.:ack2:
  13. 5-7HEAVEN

    5-7HEAVEN Active Member

    Say what you like. Your opinion means nil to me.

    I won't spar with you.

    I'm done.
  14. Easy Rider

    Easy Rider New Member

    Can't finish what you started...
    Good thing you're done.
    Have a blessed weekend and a safe Halloween!:jester:
  15. jamz1378

    jamz1378 New Member

    kids kids kids we are here to help not to argue and bicker about who is the best.
  16. jamz1378

    jamz1378 New Member


    i am in the process of putting a ht motor on my 24" chopper should be here Tuesday (fingers crossed) at this stage i am just going with the standard 44 tooth sprocket once i have it all running and broke in i will let you know how it all goes.


    THANK YOU !!!!!!!!!
  18. andyinchville1

    andyinchville1 New Member


    Generally speaking most folks w/ a 26" wheel will go to about a 32 to 36 T rear sprocket.

    Most people who have 20" wheels go w/ a 27T since it is about the same gearing about the same as a 35T on a 26" wheel (26 T is actually about the smallest sprocket that can be run using the factory 9 hole HD mount since the chain will eventually start riding the bolt heads if you get much smaller).

    On a 26" wheel, for every tooth you lose off the rear sprocket you will gain about 1 MPH in top speed (actually I think the real number is .8 MPH per tooth loss but it is easier rounding)....your speed increase of course is dependent on how much power your engine makes.

    With the above info, you can scale anticipated performance with a 24" wheel.

    Hope this helps.

    Last edited: Oct 31, 2011
  19. Neon

    Neon Member

    Umm, andyinchville everything you just said was already said by someone else before. This kid is not worth even leaving a comment because he will not listen anyway.
  20. jamz1378

    jamz1378 New Member

    to neon

    you might not want to help this kid but there are others that are readying and posting for other people me for one that is doing the same thing as this kid is

    andyinchville thank you for your assistance and will keep this in mind as i am a noob to motorized bikes but have been working on bikrs for the last 27 yrs and i am also building my own bicycles