New sprocket size?

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Sep 24, 2016
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#1
My bike right now (29'' tires) has a 44T sprocket on it and currently has a top speed of 39-40mph. It has enough torque with that sprocket to pull away from a stop with minimal pedaling. I don't mind pedaling and was looking to cruise at lower rpms and have a higher top speed :D but I'm not sure with what size sprocket to put on. Is a 36 too extreme, and what would my top speed increase be with a 36?
 


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#2
Need more info about your setup. What engine, what gearbox, what front sprocket?

Roughly, though, 44/36 =1.222 so assuming you have the power your top speed would be 40x1.222 or 48 mph.
 
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#3
2 Stroke Zeda engine dynoed at 5hp (but i dont have the MZ65 pipe), 10T front sprocket. Not sure what you mean by gear box, I don't know the reduction rate from the crank to the front sprocket..
 

Tyler6357

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#4
If you are hitting 40, I don't know how much faster you want to go on your bicycle. If you lose power going up steep hills you might need a higher tooth sprocket but if you put the 36 on it will have great top end but the bottom will be even more sluggish. If you want more low end you can put a reed valve on or get a good expansion pipe.
 
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#5
If you've got 5 HP to play with, you can make that speed. Just for reference, the Land Speed Record for 50cc bikes is 144.9 mph

Hill climbing will suffer, and starts will be sluggish.

I'm not your mom, but if I was I'd tell you to get a good set of leathers and a full-face helmet. Crashes hurt.
 
Last edited:

crassius

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#6
these are all different, best to try 41T first and go to 36T if that seems OK - then if 36T fails, go back to 41T
 

JerboaJohn

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#8
If you build more than a couple bikes, it'd be no real loss to have a couple diff sprockets as you'll use them at some point.
I have 4 now with just one 2-stroke bike :p, and need to test much bigger ones with a 4 stroke, so I know Im gonna need 2 or 3 just for that
 
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#9
If you are hitting 40, I don't know how much faster you want to go on your bicycle. If you lose power going up steep hills you might need a higher tooth sprocket but if you put the 36 on it will have great top end but the bottom will be even more sluggish. If you want more low end you can put a reed valve on or get a good expansion pipe.
Yep, I definitely should get some better gear, but I wear a full face and denim pants (which I know aren't good enough for higher speeds) every time I ride.
 
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