40 Tooth Sproket Vs. 36 Tooth

Discussion in 'Hubs, Gearboxes, Sprockets and Chains' started by bradentonmotorbikes, Jan 5, 2010.

  1. bradentonmotorbikes

    bradentonmotorbikes New Member

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    Im debating between purchasing a 40T or 36T for my bike.
    Can anyone tell me the speed increase for each sprocket?
    Were maxing like 29mph with the Stock 44T.
    I live in Florida so no hills, and Id still like to have pretty good Pickup, so which should I chose?
    Thanks :)
     
  2. Riding Rich

    Riding Rich New Member

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    A 36 is great if you have an 80.

    Not too bad with a 48.

    Just depends on how much you want to peddle at takeoff.
    You will loose a little lower end but gain tons of top end.
     
  3. Bucketh12

    Bucketh12 New Member

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    I have been using the stock 44t and have attained a top speed of ~30mph. I bought a 36t sprocket from spookytoothcycles for $25 and I plan on putting it on this weekend. I'll let you know how it fares as far as speed and acceleration are concerned.
     
  4. Riding Rich

    Riding Rich New Member

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    I can 40 to 45mph with a 36T and a modded engine
     
  5. spit_fire

    spit_fire New Member

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    do you still have pick up with the 36t or do you have to peddle everytime you go, i have a 50 tooth for the winter and it only goes about 42km/h but it can push me threw any snow and i dont peddle to take of but i want to switch to a 36 in the spring once weather permits
     
  6. Cannonfish

    Cannonfish New Member

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    There were several posts on this website in months past that estimated somewhere around a 1 mph increase in speed for every 1 tooth decrease in sprocket size.

    This estimate seemed about right to me when I switched from a 36T sprocket to a 40T - I lost somewhere around 4 mph on my top end, but then I didn't have to pedal quite so much to get moving from a stop.

    My top speeds on both these sprockets were way lower than a lot of people have reported - according to my Cateye speedometer, I maxed out at about 30 mph with the 36T and about 25 mph with the 40T. And that was getting up to uncomfortably high RPMs.
     
  7. BarelyAWake

    BarelyAWake New Member

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    Thank you Cannonfish for your honest review (^)

    Despite incessant claims to the contrary - anything beyond 35mph is a simple matter of the exponential torque demand caused by wind resistance - and NO sprocket in the world is gonna add depth of stroke to your HT.

    Changing sprocket sizes will alter your acceleration by changing where the applied powerband is - but the only things that will actually make you get a higher top speed is more power/reduced wind resistance/drag reduction.


    edit: unless ofc yer limiting yerself by redlining at 20mph... which is a completely different story - but at least yer 0-20 will be amazing lol
     
    #7 BarelyAWake, Jan 6, 2010
    Last edited: Jan 6, 2010
  8. Riding Rich

    Riding Rich New Member

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    I have calculated the rpm required to hit the speeds i claim.
    Definatly your motor needs the ability to turn 8000 rpm to hit 40 MPH with a 36T.

    Yes you can get 8000 rpm outta a HT.
    If the whole setup is correctly applied.

    In the stock world your gonna be lucky to go 30mph.

    Now granted if you sacrifice some of the low end and peddle more your speed will increase in the top end.

    If you build the motor up strong to take high revs.
    Port / and Pipe and gear correctly.
    You can go very fast.
    For every motor of a given HP there is a Torque / HP Curve.

    Essentially once the curve peaks highest torque the torque then drops off down the curve.

    So if you gear right and your power band is set right you get up to say 30 MPH fairly Quickly.
    After that torque and power drop off but you allready going 30 so you dont need as much.
    You need the motor to keep reving higher.

    There is a fellow in Erie i ride with.
    MOTORBIKEMIKE45
    Hes on the other forum.

    He has a speedo and when we ride he says we goin 27MPH before i even hit half throttle.
    I ride in traffic 45 mph Zone and keep up.
    In Erie 25mph means 35mph and i ride that all day long.

    Now honestly most will never see 35MPh but the person that dose every last thing possable to there motor and dose it correctly.

    Will see higher speeds.
     
  9. BarelyAWake

    BarelyAWake New Member

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    While I agree with some of what you've said - the above quote is dead wrong. As your speed increases (in the real world vs "calculations") you've got wind and mechanical drag to contend with and that's an exponential equation.

    [​IMG]

    or;

    http://en.wikipedia.org/wiki/Drag_(physics)

    THIS above all things is what limits the speed of these lil Chinese motors - modded or otherwise and is why I view all unsubstantiated claims with... skepticism (bicycle speedometers being famed for inaccuracy and incorrect settings - only GPS or a pace car is believable).

    This is an example of a substantiated claim;
    http://motorbicycling.com/f13/hybrid-chinese-motors-performance-tuning-14204.html#post140947
    YouTube - 2 stroke hybrid puch motorized bicycle
     
    #9 BarelyAWake, Jan 6, 2010
    Last edited: Jan 6, 2010
  10. Riding Rich

    Riding Rich New Member

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    Yes i do agree with you on that 100 percent.

    A person on a bicycle has about as much or more wind resistance as a Tractor Trailer.

    Check Out
    Thunder Products - Performance carburetor and clutching for snowmobiles, motorcycles and ATVs.

    Affordable Accurate tacometer that reads the spark.

    No way to cheat it and make it read higher or lower.

    This spring i'll get one and see what kinda RPM i really get.

    With accurate RPM it is possible to calculate accurate speeds.

    I'd really like to know my true speed.

    Too much snow here now to even attempt it.
     
  11. pauliedata

    pauliedata New Member

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    you guys read into this too much just build the motor and run it i'm going 43 mph with a 40 sprocket from jim @ manic and i did no calculations i just ran my bike i have a cns carb with jims intake a pipe from spooky tooth and some port work by me and i have a tach reading 8250 and i'm ready to turn my next one 12000 and see where i go i've already turned one 14500 on a dyno and it held together so i say build and run it see what happens good luck and keep the wheels turning
     
  12. stv1jzgte

    stv1jzgte New Member

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    Man some of these claims are gettin pretty bad, i tell ya your pullin ya pud if your gunna get up here and claim 45mph you would want to prove it. so far 1 person has.

    Get a video or get a radar gun leave the stupid CYCLE COMPUTERS to the kiddies!
     
  13. spit_fire

    spit_fire New Member

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    i dont understand y people think that the bike speedos are inacurate, a properly set bike speedo cant go wrong its to simple a magnet that passes by a pickup its math as long as the comp knows the distance between each revolution(depending on your tire size) it cant be wrong
     
  14. stv1jzgte

    stv1jzgte New Member

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    oh for cryin out loud..... lock it please!!!
     
  15. spit_fire

    spit_fire New Member

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    no but seriously if you know something i dont tell me how a set distance multiplied by the number of revolution per second or wutever can be wrong, i caim no such speed as i have a 50 tooth sprocket for the winter so i can push threw the snow we get in canada and i git 45km/h no bull**** i no its not fast but its fast enough on snow
     
  16. stv1jzgte

    stv1jzgte New Member

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    Yeh unfortunatly we humans have to set the wheel diameter usually by measuring the rolling circumfrence of da wheel.

    Get 10 people to measure the same wheel i guarantee you'll get 10 different measurements.
    So in my opinion there as accurate as the opperator
     
  17. Zenoptic

    Zenoptic New Member

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    With a Trail Tech Vapor (I have one for my stella) you can get RPM,MPH,Cyl head temp, plus it keeps time and mileage and ambient temp. I plan on geting a second one for my bike.
     
  18. Zenoptic

    Zenoptic New Member

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    They are very accurate. operator error is unlikely.
     
  19. Cabinfever1977

    Cabinfever1977 New Member

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    If you put in the wrong tire size or hit kph instead of mph you will get alot higher number for your speed than youre actually moving.
     
  20. stv1jzgte

    stv1jzgte New Member

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