1098s is 15/41 tooth gearing too much? front end comes up to easy? clearance probs? - Ducati Superbikes

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1098s is 15/41 tooth gearing too much? front end comes up to easy? clearance probs?


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#1 Brian777

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Posted 16 March 2010 - 05:25 PM

Hello Ducatisti,

On my 1098s, I am planning to get a new chain and replace the sprockets at the same time. I went up 3 in the rear on my previous 999 before and I liked it. Is 15/41T sprocket gearing ratio too much? Will it be trying to pull up the front wheel all the time.

I found on the 999 going three up in the rear helped alot on Deal's gap style curves (tight), it put me in the right gear at the right RPM instead of being in-between a too low or too high gear. I like to ride mostly curvy roads if I can.

As long as I am adding a link or two on the chain, will I have any clearance problems? with the sprocket? with the tire? is there a thread which shows how where to shave the brake caliper bracket?

THANKS so much in advance!!!
Brian

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#2 elevens

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Posted 18 March 2010 - 04:11 AM

15/41 is exactly what I run in a 520 conversion. The bike in no more wheelie prone that in ever was. However, even with stock gearing, I couldn't apply full throttle until 4th gear without the front coming up. With 15/41, full throttle in 3rd will ride the front wheel off the ground the whole way, but not go high enough where I have to back off. Around town and on a short tight track (http://www.gingerman...om/track-layout), 15/41 is far, far easier and useful. On the highway, you will give up top end. My gixxer buddy likes to take advantage of that fact :shifty

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#3 pat1098S

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Posted 18 March 2010 - 04:55 AM

As an actual ratio, 15/41 is very close to 14/38 (just slightly 'shorter' again) which many go too. This change will not affect tyre clearance, but depending on what length of chain you run, raises other issues.
As you alter the position of the axle eccentric to accommodate the different sprockets, you alter the wheelbase (obviously), and you also affect the ride height, as the axle moves on an arc (ie. up and down, as well as fore and aft).
So you need to measure your ride height before fitting the sprockets, so you can reset that (via the adjustable suspension tierod) to your original setting.
As a general rule-of-thumb, moving your rear wheel further back (ie. lengthening the wheelbase) places more weight bias on the front wheel. Many of the Superbike teams have done this over the years with the 15mm longer Magnesium swing-arm.
If you go too far with this with the stock swing-arm, you run into problems with the rear brake caliper mount, and may have problems with clearance between chain and swing-arm/chainguard, due to the larger rear sprocket.
Just be aware of the implications of these changes, and try to make just one change at a time. If you jump in and change your gearing, wheelbase, ride height and weight bias all at once, and don't like it, it becomes difficult to diagnose and cure. Having said that, the other contributor above is happy with his, so clearly it CAN be done, with a satisfactory result.
People generally just go to the 14T front to achieve the similar result, with minimal effect on wheelbase or ride height, and because they are not necessarily changing the chain at the same time.

Edited by pat1098S, 18 March 2010 - 05:00 AM.


#4 Brian777

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Posted 18 March 2010 - 05:18 AM

this is great info!! thanks so much. i originally was going to go with a quick change carrier but since afam has been backordered for a while on 41 tooth, i think on 40 and 39 too... i am planning on the supersprox. i really did not want and aluminum sprocket anyway. my previous 999 came with one wheen i bought it and it shreded rather disappointingly quickly!

thanks so much again!!
Brian

#5 Trent1098S

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Posted 18 March 2010 - 05:59 AM

I'm going to play with gearing this year for Blackhawk Farms CCS races. All last year I was chasing a problem between turn 4&5 where I'd either run out of 2nd gear, or not get enough drive in 3rd. Also getting stomped flat out on the short straightaways by the inline 4's. Blackhawk is a short, technical point & shoot track, perfect for a change. Max front straight speed is about 135-140mph so top end doesn't really matter at all, I've don't think I've ever seen 5th gear on that track. Lap records on that track between literbikes and 600's are within a half second (and currently held by a 600, if I recall correctly!).

I'll go back to stock gearing for Road America where speed matters. :)
2008 Ducati 1098S (race), 2007 Suzuki GSXR-1000 (race), 2006 Kawasaki ZX-14 (street), project bikes: 1970 Honda CB750, 1996 Suzuki Katana

#6 pat1098S

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Posted 18 March 2010 - 06:13 AM

Of course this is another aspect I didn't mention in my previous (already too long!) post - that shortening final gearing closes gears up (just as taller gearing spaces them out).
This can be an advantage at some tracks, but at others can have you changing gears too much. And of course loses the top-end referred to by others above.
I find that the 1098 is almost never lacking a suitable gear, as it has such a broad spread of torque. I should say that I find the spread of accessible torque to be my favourite property of the Ducati 90 degree V-twins I have loved since the mid-70s.
Mind you I only do track days at Phillip Island, and found Jennings (on a 996 last year) fairly challenging, being much tighter, with so many corners in such a short distance..

#7 Trent1098S

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Posted 18 March 2010 - 03:50 PM

When I order, I'll get a range of rears to play with at that track (Blackhawk). I'm just sick of not being able to be in the right gear.. either hitting the choice of "revlimit before I'm out of the corner, or not getting drive." This is purely a 2 & 3rd gear track, < 2 miles, very tight. I touch fourth on the front straight, but not for long.. it's only a quarter mile long.

Hopefully I can find a sweet spot somewhere.
2008 Ducati 1098S (race), 2007 Suzuki GSXR-1000 (race), 2006 Kawasaki ZX-14 (street), project bikes: 1970 Honda CB750, 1996 Suzuki Katana





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