Ducati Monster Forum

Moto Board => Accessories & Mods => Topic started by: cbcanada on September 05, 2014, 05:39:50 PM

Title: Rear sprocket upgrade. Whats your opinion
Post by: cbcanada on September 05, 2014, 05:39:50 PM
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?
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: DarkMonster620 on September 05, 2014, 06:28:17 PM
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 . . .
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: jduke on September 05, 2014, 06:45:04 PM
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 (//http://)
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: brad black on September 05, 2014, 07:12:53 PM
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.
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: SpikeC on September 05, 2014, 07:58:52 PM
 I have 15 front and 38 back and that is perfect. Everyone should have this setup. Or they are banana heads.
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: Ducatamount on September 06, 2014, 01:13:54 AM
(http://i1145.photobucket.com/albums/o508/jobo12/emoticons/Crying_banana_zpsb8f87a7c.gif) (http://s1145.photobucket.com/user/jobo12/media/emoticons/Crying_banana_zpsb8f87a7c.gif.html)
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: stopintime on September 06, 2014, 01:55:24 AM
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.
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: jduke on September 06, 2014, 06:27:19 AM
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...
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: ducatigirl100 on September 06, 2014, 07:13:43 AM
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  [bang]

15/42   to mutch rev's on the highway  [bang]

15/ 39 works like a charm  [thumbsup]


In my case  a good carb setup was what gave the bike life
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: 1.21GW on September 06, 2014, 08:24:44 AM
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. :)


Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: 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.

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?
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: brad black on September 06, 2014, 03:56:29 PM
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.
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: 1.21GW on September 06, 2014, 05:49:03 PM
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?   ;D

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 (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.
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: cbcanada on September 06, 2014, 05:52:41 PM
I have 15t/40t I am looking for a little bottom end without revving super high in highway
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: Skybarney on September 07, 2014, 04:36:43 AM
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)
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: cbcanada on September 07, 2014, 11:51:39 AM
I am thinking going up to 43 in the back. I currently have a 40.

Do i need to change the chain length?

Keep in mind that my bike is geared stock 42. The owner prior to me took her down to 40
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: stopintime on September 07, 2014, 02:56:36 PM
See my post on the first page  [thumbsup]
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: cbcanada on September 09, 2014, 04:38:03 AM
Quote from: stopintime on September 07, 2014, 02:56:36 PM
See my post on the first page  [thumbsup]

Bit confused so you recommend the 15/43

But the second part you mention some cons regarding it? Or am i misunderstanding ?
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: stopintime on September 09, 2014, 02:07:34 PM
Quote from: cbcanada on September 09, 2014, 04:38:03 AM
Bit confused so you recommend the 15/43

But the second part you mention some cons regarding it? Or am i misunderstanding ?

I think changing to a larger rear sprocket, or smaller front, is a good idea as it seem to please most Monster riders.
If you don't like it - go back - which BTW will be cheaper if it's only the front...
The result of 15 to 14 is the same as 40 to 43.

Mods tend to come with secondary results in addition to the intended. Different size sprockets changes the wheel base and the ride height. With the stock 104 links chain - the wheel base becomes ~9 mm shorter - maybe you'll notice, maybe not. Also, with the axle 9 mm forward - the bike will become slightly lower (can be adjusted with the ride height rod). Chain with 106 links will put the axle quite close to the 3 o'clock position, which can make it impossible to tighten after 'a while' and this position also lowers the ride height by ~ 10 mm.

If you think all this axle-, height-, links and adjustments-talk is hard to understand and get under control... I suggest doing a 15 to 14 conversion as a much simpler and cheaper method.
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: Rudemouthsky on September 09, 2014, 06:05:36 PM
I'm at 15/41 on my old 900, and I may go to 14 up front. Depending on how I like the current gearing with the new engine mods. The bike was a dog for many reasons that were no fault of the gearing.

Not that this is a survey or anything...
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: koko64 on September 09, 2014, 06:34:39 PM
15/41 on my '95 M900. Very nice compromise.
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: cbcanada on September 10, 2014, 03:43:02 AM
Quote from: stopintime on September 09, 2014, 02:07:34 PM
I think changing to a larger rear sprocket, or smaller front, is a good idea as it seem to please most Monster riders.
If you don't like it - go back - which BTW will be cheaper if it's only the front...
The result of 15 to 14 is the same as 40 to 43.

Mods tend to come with secondary results in addition to the intended. Different size sprockets changes the wheel base and the ride height. With the stock 104 links chain - the wheel base becomes ~9 mm shorter - maybe you'll notice, maybe not. Also, with the axle 9 mm forward - the bike will become slightly lower (can be adjusted with the ride height rod). Chain with 106 links will put the axle quite close to the 3 o'clock position, which can make it impossible to tighten after 'a while' and this position also lowers the ride height by ~ 10 mm.

If you think all this axle-, height-, links and adjustments-talk is hard to understand and get under control... I suggest doing a 15 to 14 conversion as a much simpler and cheaper method.

Okay i definately dont want to lower the ride height. If i do the 14t front then i can keep same height? Or is their anyway to do the 43t back without lowering the height and or not being able to possible re adjust chain.

Thanks for the clear up
Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: stopintime on September 10, 2014, 04:07:02 AM
Quote from: cbcanada on September 10, 2014, 03:43:02 AM
Okay i definately dont want to lower the ride height. If i do the 14t front then i can keep same height? Or is their anyway to do the 43t back without lowering the height and or not being able to possible re adjust chain.

Thanks for the clear up

All chain/sprocket mods and new chain lengths affect the axle position - some more than others.
If a mod, or combination of several, makes the bike lower - you can raise it back up with the adjuster rod, but it requires careful measurements and often some swearing and bloody knuckles.

So, a 43 will make the wheelbase shorter and you 'should' adjust the ride height to stock, where it is now or wherever you want it. The same gearing change is achieved with a 14 front - without changing the wheelbase or ride height much at all.

Title: Re: Rear sprocket upgrade. Whats your opinion
Post by: dbran1949 on September 10, 2014, 03:32:24 PM
I did this a few years ago in excel just to compare ratios sorted by ratio

Front   Rear   Ratio
15   38   2.533
15   39   2.600
15   40   2.667
14   38   2.714
15   41   2.733
14   39   2.786
15   42   2.800
14   40   2.857
15   43   2.867
14   41   2.929
15   44   2.933
15   45   3.000
14   42   3.000
15   46   3.067
14   43   3.071
15   47   3.133
14   44   3.143
15   48   3.200
14   45   3.214
15   49   3.267
14   46   3.286
15   50   3.333
14   47   3.357
14   48   3.429
14   49   3.500
14   50   3.571