Usefull gearing chart & a question for the technophiles

[smed]

Imagine it is impossible to get the correct size sprockets for your bike.

Lets say for this exercise the stock gearing is    15-45 = 3.00.
Lets say you can get correct fitting sprockets in 13-39 = 3.00.

So the same overall ratio is achieved,My question is at a given speed,say 70kmh, Is the countershaft spinning at the same rpm with both of these gearing options,The rear wheel at the point of contact with the driving surface must be the same to give 70kmh at the same rpm i would have thought,I am no mechanical engineer or mathematician but the more i think about it the more confused i get,or have i just got too much time on my hands to be asking dumb questions ,And no I don't need a custom one off sprocket made coz i can't get the right one just curious to know others thoughts

[evo550]

I'd imagine the engine would be at about the same rpm as the final ratio is the same between the two sets.

[tony27]

If the ratio is the same then the countershaft speed is also the same

[JC]

7000a093.jpg

Imagine it is impossible to get the correct size sprockets for your bike.

Lets say for this exercise the stock gearing is    15-45 = 3.00.
Lets say you can get correct fitting sprockets in 13-39 = 3.00.

So the same overall ratio is achieved,My question is at a given speed,say 70kmh, Is the countershaft spinning at the same rpm with both of these gearing options,

Yes, definitely

[TT5 Matt]

3.00 is 3.00 reguardless of the spocket sizes but smaller countershaft spockets like 12 teeth or so sure help wear your chain out faster then larger spockets

[smed]

Thanks guys,I have got my head around it now