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Post by colinjay on Jun 5, 2007 17:31:36 GMT -5
As I said above, I have always been a bit sceptical about the calculated speed I got after that run. It is really based on the tacho being 100% accurate, and we all know what 1970's japanese instruments were like. So I would say it could be as much as 10% high, which would give a real SOG of about 190 - 195kph.
For information, the calculated top speed of a SR500 on STD gearing at redline is 170kph (106 mph). This is based on the quick (but slightly inaccurate formula) of:
RPM / Overall Gear Ratio = Rear Wheel Revs/min
Rear Wheel Rev/min x Tyre Circumfrence = Distance Travelled/min
Distance Travelled/min x 60 = Distance Travelled/ hour
So to put some numbers to it;
7500rpm / 5.482 (overall top gear ratio) = 1368 R/W rpm
1368 x 2.08 (circumfrence in metres of an average 425 x18 tyre) = 2845.7 Metres/min
2845.7 x 60 = 170740.6 Metres/hr = 170.74kph
This formula is a rough guide as it does not take into account tyre deformation under the weight of the bike and rider which will reduce the rolling radius of the tyre and therefore the rolling circumfrence, which will effectivle lower the speed.
As you might guess I am a bit of a mechanical nerd, i.e. if I meet you, I won't remember your face or name but I would remember your bike and any technical details of it!
CJ
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Post by andy on Jun 13, 2007 14:43:34 GMT -5
hi lads,what a good post! this top speed thing used to get to me from time to time,given the right conditions i've seen 95m.p.h on my sr,but realisticaly 85-90 is about right .anymore, stability is not so good,but one big difference ive found is to 'tuck in',by that i mean especially elbows and knees have a look at the speedo you will be surprised.without doubt the most satisfying is 70 in top pulling just under 5,000 revs [17 front sprocket,open muffler,big k&n].like some of you i cant make top revs in top gear even with the 16t sprock,ive always felt the gap inbetween 4th&5th a bit to steep.17t gives me 15 m.p.h per 1,000 r.p.m on my clocks.food for thought lads,dont get bogged down with this top end thing like i did up until i had a chat with myself,if you want to sit at the ton get a bigger but equally important a more stable bike.the sr is one great bike,use it how it is meant,plenty of grunt and a 'pleasant' cruising tool. regards to all, andy
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