Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 999 / 749 > '04 749S - lowered gearing?

[yellowisfriedegg]

Originally posted by jk2

I have a 999s, with 1 tooth less on the fr sprocket, how much more difference does going up one on the rear make? Any problems with chain length?

One down at the front and 1 up at the back is the equivalent of 3 (and a bit) up at the back , the advantage being you do not need a new chain to do it where you probably would have to replace the chain too if you just altered the rear sprocket.

In reply to Shazzams post , I will check the front sprocket on Mrs eggs 749S when I get home for number of teeth , I thought it was a 15 front standard so going down to a 14 is not an issue , I do know without checking though that ALL 749's and 999's come fitted with 525 chain and sprockets as standard.

[Edited on 31-5-2004 by yellowisfriedegg]

[Shazaam!]

You're right, I had forgotten that the 749’s get 525 chains. Probably more for parts standardization than for strength requirements. I remember from the product introduction that that was one of the major design objectives of the new models.

[nelly]

According to the info I have here all the 749's have a 14T front. 13T are like hens teeth and run the chain too tight. Only real world alternative is to up the rear. 3T is a good start, and you may get away with the standard chain?
Both Renthal and STM do alloy real sprockets for them now. Rentha are about £25, the STM £58 but are real works of art

[electricsheep]

Looking at ducati.com (not sure if this is accurate)

749S has 14F 39R with primary drive 1,84 (is this 1.84:1 ? )
749R has 15F 35R with primary drive 2,11

I not sure which way the maths goes, so which has taller gearing ?

Rob

[749R]

If it's any help, I went up 3 teeth on the back, the gearing is spot on now and still using the standard chain.

[andyb]

When you say still using the std chain to get an extra 3 teeth in. How much did you move the rear wheel forward then? which mark are you on on the swingarm? Any piccies?

[Shazaam!]

749R, going from a 15/35 to a 15/38 using the same chain will shorten your wheelbase 12mm. In general, it's better to go to a longer wheelbase than a shorter wheelbase because it improves high speed handling. Superbike corsa swingarms, for example, are 15mm - 25mm longer than street versions for this reason. Shortening the wheelbase beyond the stock setting is really not a good idea.

A good approach gearing is to set the wheelbase at maximum (still allowing the adjuster an additional 10mm for chain stretch) and then use a combination of sprockets and chain length to shorten the gearing.

The length of each link from pin-to-pin for a 5XX chain is 5/8-inch (16mm.) So in your case of using a 15/38, if you use the next longer length (adding two links at a time) you’ll get a wheelbase 4mm longer than stock instead of 12mm shorter. I’d do it.

[andyb]

We knew that........

[Shazaam!]

I'll get me coat ...

[andyb]

er... not really...