Rear Sprocket.

Discussion in 'Frame Mounted Engines' started by Drunkskunk, Aug 31, 2008.

  1. Drunkskunk

    Drunkskunk Member

    I've got HT "80" i'm looking to install soon, but the guy who sold it to me said he can hit 35-40 with it. The book spec it at 38mph. Thats fine, but I want to go slower

    Yeah, thats right. Slower. :shock:
    I'm going to title it as a moped, and for legal reasons, need a max speed of 30. That, and from personal experiance with Ebikes, 35 on a bicycle is well beyond the capability of bicycle brakes or suspensions to handle. And then there is the added torque and acceleration of lower gearing. torque is good!

    Long story short, rough math shows I need a 60 tooth rear sprocket, or a front sprocket with 1 fewer teeth, and a 54 tooth sprocket to hit 30 max.
    Are those parts available, and if so, where would I find them?

    Also, who's a good reputable vendor for parts like that?
    Who should I avoid at all cost?

  2. HI,

    Yes, sprockets are available that can read more about them at

    Hope this helps you.

  3. Drunkskunk

    Drunkskunk Member

    Cool, thanks. I like the possiblity of the disk brake mounted sproket, too. I might have to look into changing hubs.

    WHat about the motor's drive sprocket. I saw one listed on a site that also soled a kit to let you drive a HT through the main chain ring, but that was a while ago, and I don't remember the link. anyone see this, or know who else might have a diffrent motor side drive sprocket?
  4. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    As to your original question, a comfortable cruising speed
    is far more important than your top speed.
    If you are geared too low your engine will be screaming and
    vibrating you to death.
    Don't make any changes until you have tried it out.

    No one is going to check your top speed if you title it as a moped.
    If you don't want to go that fast don't twist the throttle all the way....
    Last edited: Sep 1, 2008
  5. HoughMade

    HoughMade Guest

    I agree- I understand the legal issues, but I think you want to try it out with a standard sprocket before getting something custom made. From what I have read, with a 44 tooth, some of these don't do much over 30 anyway.
  6. relaxxx

    relaxxx Member

    Yeah 44T on my HT was doing 26MPH absolute screaming max. Found 36T has just as much hill climbing punch and now my motor is not screaming to do 25 and I increased my mileage a little, not much (70MPG to 75). Like I've said 44T to 36T was not nearly as big a difference as I anticipated so I'm working on getting even smaller sprocket. My motor seems to have plenty torque to spare. Smaller sprocket = lower RPM = longer lifespan + More MPG = More $ for me! Get a small sprocket! You will love it!!

    Can you imagine if Cars and trucks had to be designed to red line at 55MPH as a form of speed control!? Absolute disaster, why should motored bikes be forced to do this? It's simply retarded!
    Last edited: Sep 6, 2008
  7. Skyliner70cc

    Skyliner70cc Active Member

    There is nothing retarded about it. These motors are single speed and you have to decide what you want, hill climbing ability at expense of top speed, or top speed at the expense of hill climbing ability.

    Luckily, we have a jackshaft kit that can be purchased to give more flexibility.