[ST] Re: Gear ratios year to year

["barry.croft" <barry.croft@xxxxxxxxxxx>]

Interesting thread. This keeps coming up on the list, but every time it does
I learn a little more.

FWIW I swapped from 19 to 18 on my RS, and I love the extra pull it gives.
Not TOO wild, but a definite improvement. NOT just for wheelies (tho it
does) but it's also better just for plain trickling about in traffic and so
on. And the top speed has actually improved. On 19 it ran out of puff way
before the redline (tho I am a big fat b******) and topped out at about
150mph. On 18 it pulls all the way to the old 9500 redline, at 155mph. Maybe
it'd do more - that is just where I chickened out and backed off, but with
the latest tune for the race can, the actual physical rev limit seems to
have moved up to over 10000.

Maybe Triumph chose 19 to suit a smaller lighter rider? Or more likely for
laziness and economy on fast European roads. Although it did feel a bit
busier on motorways at first (I kept fishing for another gear) I soon got
used to it. On my mixed riding I couldn't measure any change in fuel
consumption, and I'd guess what I lost on fast straight cruising I gained by
being in a more efficient gear in twisty bends.

I shortened the chain from 104 to 102 at the same time, because I thought
the smaller front sprocket would lose me too much of my adjustment at the
back ... which was a mistake! I've since learnt that there's plenty of
adjustment anyway. The downside is that the tyre now runs too close to the
swingarm, making it impossible to fit that carbon hugger I lust for, and
*possibly* even causing a run of punctures I suffered. It has also shortened
the wheelbase, and tho this may have improved handling slightly in the
twisties it has also made the bike more 'nervous' on fast straights and in
bumpy corners.

Final comment on ratios. The ideal is to have prime numbers of teeth (e.g.
19/43) on both front and rear sprocket, since that way every front tooth
pulls via the chain on every rear tooth completely evenly over time. An even
number on one halves this even spread, and even on both at least quarters
it. The very worst is to have common factors - so for (silly) example, if
you ran a 16/32 with 64 link chain (I said it was silly) then 1 damaged
front tooth would transmit damage to just the same 4 chain links and hence
to just the same 2 rear teeth, all the time. In that respect at least, 17 or
19 is better than 18, and 43 better than 44 or even 45.

Barry
00RS
97S3


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