How to select gear/sprocket ratios for vehicle?

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The mass of vehicle with driver is 150kg. The specification of motor are 12kw, 27Nm torque, using 110/80 R17 wheels . 1. what is the general consideration to do transmission calculations of bikes 2.How to select gear ratios and sprocket ratio?
 
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"110/80 R17 wheels ." ... This does not help we need to Know the RADIUS of wheel , including tire.
 
oz93666 said:
"110/80 R17 wheels ." ... This does not help we need to Know the RADIUS of wheel , including tire.
110/80 R17 is enough information to calculate the radius/diameter; the 110/80 is a tire specification even though OP said "wheel".
 
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oz93666 said:
"110/80 R17 wheels ." ... This does not help we need to Know the RADIUS of wheel , including tire.
I think the below example will be clear you doubt on calculating radius.
Example: 285/75R16 (285 X 75 / 2540 x 2) + 16 = 32.8 inches tall.
 
I guess 'tall' means dia?? ... In which case we have a radius 0.42 meters

We are told the torque is 27Nm which means if the wheel had a radius of 1 meter , it would push horizontally on the ground with a force of 27 Newtons ...

and this would be the force accelerating the bike and passenger ... but the wheel is smaller and so we get more force ... 27/0.42 = 64.3 Newtons

Since the mass is 150kg , the acceleration is ... F=ma ... 64.3/150 =0.429 m/sec

1MPH = 0.45m/sec

So that's the acceleration with no gears ... an increase of 1MPH every second ... it would take you 20 secs to reach 20MPH !

You need to decide what is an acceptable acceleration 5MPH increase every second would need a 5 to 1 gear... that's 0 to 30MPH in 6 secs

If you want to reach 30MPH in 3 secs , that's an accn, of 10MPH/sec ... a 10 to 1 gear is needed .
 
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Since the mass is 150kg , the acceleration is ... F=ma ... 64.3/150 =0.429 m/sec

The 0.429 is acceleration you put it as m/sec how? i can't able to get it.
 
Thathrooban said:
The 0.429 is acceleration you put it as m/sec how?
It's m/s2.
 
A.T. said:
It's m/s2.
yeah that's why I ask him.
 
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