Currenty i have a 40t rear
My bike (2005 s2r800) should be stock 41t
I am looking to go to 42 or 43
Anyone have any input on which?

you want "fast of the line" or top speed and "fuel economy"?

the higher you go, the "slower" the bike will become from standing to moving and you will use lots of low gears in commuting/city riding . . .

What tooth sprocket is on the front? Dropping 1 on the front is like going up 3 on the back.
Here a good link to see what different sprockets will do.
www.gearingcommander.com

i'd go 43, as i found them nicer with a 14 front and the std rear.

while there is truth to the theories of going bigger or smaller, often there's gearing that just works better all round.

 I have 15 front and 38 back and that is perfect. Everyone should have this setup. Or they are banana heads.

Do you have a 14 or 15 on the front?

If a 15, yes, go 43 on the rear - much more fun and easier city riding - no loss of top speed (wind resistance is greater than power at top speed)

The axle, in it's eccentric hub, will be positioned 9 mm forward from the usual 5 o'clock position ( = shorter wheel base) which probably isn't a problem (it will become a tiny bit lower in the back). This with stock chain length 104 links. 106 links will position the axle so far back that you might not be able to adjust it far enough when the chain gets some miles on it.

I've always heard that people who think 15 / 38 is perfect like to stuff an over ripe banana down their pants before a ride. I have no proof of this, just something I've always heard...

I did a bot of trial and error

15/ 41 is what I add  : when I rode whit the gang, it alway's seam that I was missing a gear 

15/42   to mutch rev's on the highway 

15/ 39 works like a charm 


In my case  a good carb setup was what gave the bike life

I say do the 43.  You are familiar with 40 because that's what you have.  Try the 43, and after a year if you don't like it go back to the 40 or change to a 38-39.  Then you'll know what the difference feels like.

And just to add another datum to the cairn, I'm currently running 15/42 (stock for mine is 15/39; bought bike used with 14/39 on it).  I am happy with it.

the girl seems to know the most about these bikes, but i trust the guy because he has magnum as his avatar.

i just got an 1100 evo, which feels slow compared to my m900. guess i'll go out and count the sprockets on my old bike and change to that?

please bear in mind all gearing conversations are very much model specific.  we're talking about an s2r800 here, which has a different gearbox and possibly primary drive ratio to all bigger 6 speed models.

Quote from: showerfan on September 06, 2014, 02:29:13 PM
the girl seems to know the most about these bikes, but i trust the guy because he has magnum as his avatar.

How can you be sure I'm a guy?  

FTR - I would trust the guy that has a whole webpage on ducati sprockets.  How humble of you, BB, not to point to this...

http://www.bikeboy.org/ducgearing.html


Showerfan: It may seem like a complicated read, but it actually is simple enough my idiot self understood it, and it allowed me to reset my 14 front to a stock 15 and then adjust the rear to roughly match the ratio I had.  Likewise, you might investigate what your m900 was on the chart and then figure out what is comparable for the 1100 if you want to keep your 900 final drive gearing.

I have 15t/40t I am looking for a little bottom end without revving super high in highway

I went 15/43.  Runs out nicer than the straight 14t as it is not quite as short.

As soemone else said, gearing is all about riding style.  I am a canyon carver and rarely run above 85mph.  The few times I do it I can skip shifting again and the M1100 evo will still run out to a stated 136.  (123 actual)