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Re: [ST] Re: sprockets
- Subject: Re: [ST] Re: sprockets
- From: "Mike Bostock" <mike@xxxxxxxxxxxxxx>
- Date: Mon, 19 Apr 2004 16:04:30 +0100
In your message regarding Re: [ST] Re: sprockets dated Sun, 18 Apr
2004 21:12:09 -0400, Garry Simmons said that ...
>GS- 43/19 gearing is a final ratio of 2.263
>GS- 43/18 gearing is a final ratio of 2.388 a change of 5.5% from stock
>GS- 45/18 gearing is a final ratio of 2.500, a change of 10.5% from stock
>GS-
>GS- You can calculate other combinations if you care, but the bottom line is
>GS- that you'll spin 5.5% more RPM for the same MPH with 43/18, and 10.5% more
>GS- RPM for the same MPH with 45/18. Of course that means you'll lose that many
>GS- percent off your theoretical top speed too.
43/18 ('99 stock)
Speed @ 10000 rpm
1st 63.44589
2nd 89.05288
3rd 112.2121
4th 134.2597
5th 150.2963
6th 161.4588
45/18 (me)
Speed @ 10000 rpm
1st 60.62607
2nd 85.09497
3rd 107.2249
4th 128.2926
5th 143.6164
6th 154.2829
43/19 ('00 stock)
Speed @ 10000 rpm
1st 66.97066
2nd 94.00026
3rd 118.4461
4th 141.7186
5th 158.6461
6th 170.4288
Acknowledgement to BRG for his spreadsheet.
Also from BRG (Ex Wolfram)
<Quote>
Keeping a 108-link chain will mean that other ratios alter the
wheelbase (nominal 1470 mm) and ride height as follows:
Height Wheelbase
17/43 -1.07 +3.74 to 1473.74 mm
18/45 -1.84 -8.51 to 1461.49 mm
19/43 -0.06 -3.73 to 1466.27 mm
A shorter wheelbase will make steeing quicker/lighter, but will mean
less straight-line stability at speed. My change to 18/45 has made a
noticeable effect in this area - IMHO for the better - but that's the
way I ride!
Reduction in ride height will mean less cornering clearance, though
I'm not of the opinion that 2mm makes an awful lot of difference!
</Quote>
- --
Mike Bostock
http://www.toothfairy.co.uk/
Wales & SW ST Riders
http://www.sprint-st.org/
'99 Red ST
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