Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > General Motorcycles only > Effects of changing sprocket sizes

[davep]

Could someone explain the effects of changing sprockets?

Some people talk about reducing the front sprocket size, others talk about increasing rear sprocket size, etc.

I understand that changing sprockets will impact top speed /acceleration, as you are affecting the final drive / gearing.

But can anyone explain which does what and what changes you might expect? For example, if you change a sprocket(s) to improve acceleration, how much might the top speed be affected?



Many thanks,

Dave.

[Rattler]

As a quick response;

If you make the front sprocket smaller this has the same effect as increasing the number of teeth on the rear sprocket. (if you reduce the front sprocket by 1 tooth, this has the same effect as adding approx 3 to the rear).

This move will make the rear wheel rotate faster for a given amount of revs, and the bike will accelerate faster, but then when the bike reaches maximum revs in top gear the rear wheel is actually spinning slower than if you had the standard gearing on. (if that makes sense). In reality this effect on top speed may be worth 10mph or so at the top end, but as you're unlikely to hit top speed too often (if at all) has no significant impact.

For a 996/748 changing the gearing is a popular move as you can improve the rideability of the bike. The easiest way to do this is to reduce the size of the front sprocket. This will have a potential detrimental effect on the chain (as its not designed to rotate around a smaller cog than standard. So this may effect the wear rate of the chain.

The best way to achieve this gearing change is to add 2 or 3 teeth to the rear, but here you run into the potential problem of requiring a longer chain. Do most people do what's easiest and swap the front sprocket for a smaller one.

For the DD racing, I am trying to gear trhe Monnie so that she will reach peak revs in top at the fastest part of the track, (which may only be 110mph) this may mean gearing the bike by going down one on the front and up 2 on the rear (as I did at Cadwell).

HTH
Tim

[Carbon749]

One thing that was pointed out to me about going for a smaller front sprocket on the 748 / 9**. Not sure if it's true but I was told .....

9** have a 15 tooth sprocket and a 748 has a 14 tooth sprocket as standard. Dropping a 9** down to 14 tooth is OK, but you can't drop the 748 down to 13 tooth sprocket as the diameter is too small for the chain.

[rockhopper]

That is all true Mr Carbon. You can go to a 13 tooth though but its not recomended and the chain rubs on the top of the swingarm.

[Wylie1]

Basically, smaller sprocket on the front and/ or bigger rear sprocket = bigger grin

I've fitted a larger rear sprocket to my 749s (2 extra teeth to keep the standard chain). Acceleration on road + track is definitely better/ more fun at all speeds. Top speed seems to be reduced by roughly 5mph'ish (tested on private roads obviously officer ).

[Glyn]

see here
http://ducatisportingclub.com/xmb/vi...6156#pid142860