How do I work out theoretical rear wheel revolutions?
 

OK, messing about with stuff, and was just trying to work out how you calculate the theoretical wheel speeds for a known RPM and gear. I've got the gear ratios, and Primary and Final reduction ratio, but my brains tired, and I can't quite work out the figures.

Anyone got any ideas?

Re: How do I work out theoretical rear wheel revolutions?
 

i would have though rear wheel rpms would be

RW RPM = (Engine RPM) * (1 / Gear Ratio) * (1/Final drive ratio)

Gear ratios:

1st = 2.461 (32/13)
2nd = 1 .777 (32/18)
3rd = 1 .380 (29/21)
4th = 1 .125 (27/24)
5th = 0.961 (25/26)
6th = 0.851 (23/27)

Final drive ratios:

SV650 = 3.000 (45/15)
SV650S = 2.933 (44/15)

Re: How do I work out theoretical rear wheel revolutions?
 

Ta :D

Re: How do I work out theoretical rear wheel revolutions?
 

well i know that if i'm in second gear 5k rpm is as near as dammit 30mph

so, a bit of math

rear tyre is 17 inches in diameter, which = 0.432m, therefore the wheel's circumference is (2 * pi * radius) = (2 * 3.14 * (0.432/2)) = 1.36m

30mph = 48000 meters/hour = 13.3m/s

number of wheel revolutions per second = 13.3/1.36 = 9.78

therefore rear wheel rpm = 9.78 * 60 = 587rpm
______________________________________

now calculating the other way:

5000rpm * (18/32) * (15/44) = 958rpm

sounds reasonable to me:cool:

Re: How do I work out theoretical rear wheel revolutions?
 

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Re: How do I work out theoretical rear wheel revolutions?
 

units?:confused:

Re: How do I work out theoretical rear wheel revolutions?
 

...

Re: How do I work out theoretical rear wheel revolutions?
 

i meant the diameter...

using inches in this formula:

gives you just over 1000rpm for 30mph in second gear - not right unless they accidentally put the cogs on my bike back to front...

Re: How do I work out theoretical rear wheel revolutions?
 

Could I ask - why do you need this information? Will it materially improve your life?:D TBH I've managed many years without even thinking of the calculation let alone trying it and I can't say I'm bereft:p

Re: How do I work out theoretical rear wheel revolutions?
 

Isn't 17 inches the wheel diameter rather than the tyre diameter? And there's a primary gear reduction to factor in as well?
Anyway, my head's hurting and I can't find a late night kebab house in Willenhall that delivers and I've got to go to bed hungry so I'm in a bad mood:(