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Fool of the universe
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Discussion Starter · #1 ·
Nothing dificult I am sure for people to answer, so here goes. I was reading something about the new 696 Monster online and it said the following:

The gearing is miles too high and when you buy this bike from your Ducati dealer absolutely insist on having a 14 tooth gearbox sprocket instead of the 15t which comes as standard. This is not Ducati's fault - merely a by-product of getting through Euro 3 emission regulations. Unless you intend on competing at Daytona, gear it down

So what is the reasoning behind this? What does the size in sprockets mean really in this situation. THis is on the rear obviously right? Can you just tell by looking at it or counting teeth what is currently on it?

Figured I'd ask, that's what the forum is for.

Thanks.
 

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OO=[][]=OO
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That would be in reference to the front sprocket. To help qualify the bike as ‘euro 3’ the larger front sprocket is installed, which will lowers the RPM’s in any given gear at any speed. This will reduce both noise and exhaust emissions. The larger front sprocket is a good thing though; it allows for a more lenient tune on the engine and is very easy to change out once the bike is brought home. This is a common practice with other manufacturers too.
 

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He's talking about the front sprocket. A smaller front sprocket will give you move acceleration, but you will loose* some top end. It's like when you changed the front gear on your 10-speed. The smaller sprocket allowed you to accelerate faster, but the b***** sprocktet gave you a faster top speed.

*Loose spelled incorrectly IAW unwritten internet law.
 

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Silent pipes take lives
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Dropping from 15 to 14 teeth on the rear increases torque by 7.14%. Of course, it lowers speed at redline in each gear by 6.67%.

The initially taller gearing, as mentioned before, lowers engine speed at any given speed/gear combo, which reduces both emissions and noise.
 

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Fool of the universe
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Discussion Starter · #5 ·
ah.. okay, this clairifies things.

So do you agree with the writers argument though that this is totally not neccesary for just regular occasional spirited street riding??
 

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Silent pipes take lives
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ah.. okay, this clairifies things.

So do you agree with the writers argument though that this is totally not neccesary for just regular occasional spirited street riding??
I'll put it this way: the stock gearing isn't going to suck. It won't be "all that it can be," but it'll do and riding will be plenty spirited.

I went up two teeth on my Ducati's rear sprocket. The "seat of the pants" difference was minor, but it did make sixth gear usable at legal speeds. :D

I wouldn't worry about it. :cheers
 

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Dropping from 15 to 14 teeth on the rear increases torque by 7.14%. Of course, it lowers speed at redline in each gear by 6.67%.

The initially taller gearing, as mentioned before, lowers engine speed at any given speed/gear combo, which reduces both emissions and noise.
correct me if i'm wrong, but isn't torque created at the crank?
 

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Silent pipes take lives
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correct me if i'm wrong, but isn't torque created at the crank?
Force is converted into twisting force (torque) at the crank, which is then transmitted through the clutch, transmitted and multiplied (or divided) through the transmission, and transmitted and multiplied through the sprockets/chain (or differential in a car.)

We'll ignore frictional losses for a moment.

If your engine outputs 60 lb. ft., you're in first gear, that gear ratio is 3:1, and you have a 15-tooth front sprocket and a 40-tooth rear sprocket (2.67:1), then:
The engine produces 60 lb. ft.
The transmission's first gear ups that to 180 lb. ft.
The sprockets up that to 480 lb. ft.
 

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Wow you guys are like encyclopedias (^^^ you in particular). Learned some interesting stuff today :beer
 

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Force is converted into twisting force (torque) at the crank, which is then transmitted through the clutch, transmitted and multiplied (or divided) through the transmission, and transmitted and multiplied through the sprockets/chain (or differential in a car.)

We'll ignore frictional losses for a moment.

If your engine outputs 60 lb. ft., you're in first gear, that gear ratio is 3:1, and you have a 15-tooth front sprocket and a 40-tooth rear sprocket (2.67:1), then:
The engine produces 60 lb. ft.
The transmission's first gear ups that to 180 lb. ft.
The sprockets up that to 480 lb. ft.
thanks for the 411. I was unclear to exactly were torque is generated from.
 

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A guy on a scruffy bike
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Since the Monster is generally considered a short trip bike rather than a long distance tourer, and since as a naked bike you generally don't want to be spending a lot of time at high cruising speed anyhow, it is *very* common to gear down your Monster from stock. Mine came stock with 15t/39t (front/rear); going to a 14t/39t or even 14t/41t was almost universal; livens up acceleration and responsiveness at the expense of a lower top speed and a bit more busyness and lower highway gas mileage.

I actually went the other way, though. Since I spend a lot of my local time on the freeway, and travel/tour on it more than I ride the twisties, I went to 15t/37t for a more relaxed highway ride and a small lift in gas mileage. Acceleration suffered a small bit, but the big twin is torquey enough for that not to be a problem.

PhilB
 
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