Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > chain

[TP]

Originally posted by Redruth
Whatever the outcome of the know all quiz, I'm sending you a prize

There'll be some extra postage on that one!

[madmav]

Ok i have a Question for Shazzam?

When i was in germany on the AutoBarn
and we all did some high speed runs


i noticed the maximum speed i could get in 5th gear would not increase when i hooked 6th gear

some times on a down hill section she would gain 4-8 mph more!

and it would not pull anymore revs in top gear!!

as i have spent most of my life on jap bikes !

i just assumed the bike had run out of HP (Horse power)

and therefore had not got the power to pull back into the sweetspot in 6th gear

so if i go for the 15/43 option will the bike give me more top speed because it can pull back up into the power /torque range in top gear?

or will it just BLOW UP!!!

[Redruth]

Originally posted by tp-996

There'll be some extra postage on that one!

That's already factored in, mate!

Not that I intend to prejudge this whole thing, but frankly, he's out there in no-man's land, aka HarleyDavisonworld.com and he needs all the encouragement he can get!

[Edited on 9-2-2005 by Redruth]

[Shazaam!]

Originally posted by Redruth
What does this mean

"your tach at 70mph will read about 750 rpm higher (4,647 instead of 3,890)"

With your current stock 15/36 sprockets and 94-link chain, your tach will read 3,890 rpm in 6th gear when your speedometer reads 70mph.

When you change the rear sprocket to 43-teeth (which requires a longer 98-link chain,) your tach will then read 4,647 rpm in 6th gear when your speedometer reads 70mph.

You'll be reving higher at the same road speed - in any gear. You'll also gain more torque for starting-off too.

Clear?

[Shazaam!]

Originally posted by madmav
Ok i have a Question for Shazzam?

so if i go for the 15/43 option will the bike give me more top speed because it can pull back up into the power /torque range in top gear?

It depends on a number of factors, but essentially you've got the right idea. To reach the highest to speed you need to keep lowering the gear ratio until you max your terminal velocity concurrent with your red line. Trial and error will give you the answer. The biggest factor is air drag which quadruples when you double speed. 15/43 is a nice all-round ratio, but probably isn't the best top speed ratio.

[madmav]

Thanks Shazzam!
i'm sure i'm running 14/38 at the moment not sure i will check to morrow!

[Redruth]

Thanks Shazaam. I actually understand all of that now.

[Edited on 10-2-2005 by Redruth]

[andyb]

Originally posted by Shazaam!
Sorry, let me clarify ...

Andyb made a general suggestion that 15/38 was a good choice for 99* bikes. I just wanted to point out that the 996's are an exception because of their much higher gearing.

The 996R's use the close-ratio box like the 998's and 999's.

I wasn't suggesting using 15/43 for a 996R, adam.

Damm! I thought id caught him out, sat here smiling to myself....

[adam]

Right, im going to buy 15/38. also im going to buy some spare teeth so i can glue them on depending where i am riding. Bostic or evo stick should work on metal. this way i will cover all situations.

[andyb]

get a renthal carrier mate and two or 3 sprockets 38.40.42... job done!