Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 999 / 749 > 749r v's 749s - gearing differences

[Carbon749]

Hi,

I may be being a numpty and there may be a simple answer, but, according to ducati web site the new 749r has a 15 tooth front and 35 tooth rear, whilst the 749s has a 14 tooth front and a 38 tooth rear.

Any idea why the difference ?

I know that on the 9** style bikes that have 15 tooth front sprockets a quick and easy mod is to fit the 748 14 tooth front sprocket .... is the same case on the 749r ?

Has any one with a 749R played around with their gearing ?

[Carbon749]

boing

[Twinfan]

15/35 and 14/38 will give very similar overall gearing. As to why they're set up that way I have no idea.

I would think going to 14/35 would be a good thing, and you could use the standard chain. Shazaam gave a chart on here a while back with ideal gearing for each Duke. You might want to do a search and dig it out...

[Twinfan]

Found it:

[pedro]

ive gone 14t at the front, very happy with

[Ducnow]

Originally posted by Twinfan
15/35 and 14/38 will give very similar overall gearing. As to why they're set up that way I have no idea.

Sorry, but if you want a closer gearing shouldn't you go a tooth less on the front or add more teeth to the rear???
And that would mean that 15/35 is wayyyyyyyyyyy taller than 14/38, right??
I mean, if it was 14/35 vs 15/38, then it would be more balanced, right???

Now...... how come the 749R have such tall gearing

[JPM]

Probably the box.... it'll be a tall first/close ratio box in the R over the other models I'm guessing

[Ducnow]

Originally posted by JPM
Probably the box.... it'll be a tall first/close ratio box in the R over the other models I'm guessing

Maybe that's it.
Anyway........ i didn't expect such a big difference in gearing.....

[electricsheep]

it is because the 749R has a different primary drive ratio, therefore it needs a different final drice ratio (chain and sprockets)

[Shazaam!]

Any final drive ratio represents a trade-off between acceleration and gear range. The lower the ratio, the quicker the acceleration and the narrower the range of speed for any one gear. Consequently, a lower final-drive ratio means that while the bike scats aggressively in any gear, it requires a more shifting because the gear range is so narrow. Add to that a closely-spaced set of transmission gears and you have a bike that requires more fiddling with gear selection to stay on the torque curve.

The stronger 749R engine will give better acceleration in any gear so it need less help from the gear ratio.