What is the impact of sprocket changes?

cos_fz1

cos_fz1

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Everyone rides their bike a little differently. I am looking for input on what different sprockets do to the bike, to decide if I want to change sprockets.

Do you change the actual sprocket size larger or smaller for the front or the back or is it just a change in the number of teeth on the same size sprocket?

What is the impact of replacing the sprocket if you put a larger sprocket on the front or back?

What is the impact of replacing the sprocket if you put a sprocket with more or less teeth on the front or back?

Thanks.
 
Adding either a smaller front or larger rear will give you more acceleration and more wheelies and less MPG. A larger from or small rear will give you in theory more top speed (wind resistance and HP play part), more MPG
 
The number of teeth changes the size of the sprocket period. The spacing between teeth have to remain a constant thus less teeth, smaller circumference. So, dropping a tooth on the front means slightly less MPG, better acceleration, shorter shifting and less top end. This also extends the wheelbase a bit because you have to adjust the rear wheel backward to take up the excess slack. It changes the dynamics of the bike just a tad.

If you leave the front the same and add teeth to the rear, this shortens the chain and creates a shorter wheelbase. Cornering becomes quicker. ;)

If you drop teeth in the back, just as Johnny pointed out, less acceleration, more top end speed, lower RPMs at cruising speeds which equates to better MPG.

So, it boils down to what is your preferred style of riding? More sport and cornering? Or more cruising/touring?
 
FZ1inNH said:
So, it boils down to what is your preferred style of riding? More sport and cornering? Or more cruising/touring?
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Thanks for information. I am considering the option of more of a crusing/touring configuration.

From what I have read, if you make any sprocket change, you need to get some type of speedo healer, correct?
 
cos_fz1 said:
Thanks for information. I am considering the option of more of a crusing/touring configuration.

From what I have read, if you make any sprocket change, you need to get some type of speedo healer, correct?
Click to expand...

Actually, it depends.... The stock bike is about 6.9% off in the negative direction. When I dropped one tooth in the front, I had to set my SpeedoDRD to -11.9% to correct it within 1 - 2 mph off my GPS. If you were to drop two or three teeth on the rear sprocket for the cruising/touring, your speedo will actually move toward the corrected state. I'm not sure what percentage that will be but you'll actually have less reason to go buy any type of speed healer than if you'd dropped a tooth in the front. So, in your case, no, you do not need a healer as you're closer to dead-on GPS than stock.

Also of note: The Gen II riders who switch from a 190/50R to the 190/55R have about the same experience as two teeth removed from the rear sprocket. What this means is, if you are close to a tire change, you could get the same effect with the taller tire on the rear. ;)
 
FZ1inNH said:
...
Also of note: The Gen II riders who switch from a 190/50R to the 190/55R have about the same experience as two teeth removed from the rear sprocket. What this means is, if you are close to a tire change, you could get the same effect with the taller tire on the rear. ;)
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cos_fz1 said:
Thanks again.... I may just wait until a tire change for the rear and see how that works.
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One thing to consider is that the FZ1 has a pretty tall first gear (same as the R1, but heavier bike) so if you put a 190/55 in the back or use a smaller sprocket in the back it will be a little more difficult to launch from a stop. This will become especially apparent if riding with a passenger...just something to keep in mind.
 
NJFZ1 said:
One thing to consider is that the FZ1 has a pretty tall first gear (same as the R1, but heavier bike) so if you put a 190/55 in the back or use a smaller sprocket in the back it will be a little more difficult to launch from a stop. This will become especially apparent if riding with a passenger...just something to keep in mind.
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Thanks Tony. Forgot that caveat of changing the rear. But, it won't be too bad for the casual rider. Someone who wants to compete at the light may not like the change at all. I should also mention that should you drop the rear tooth count, make sure your idle is set to 1200-1300 RPMs or you could stall the bike more than you want. ;)
 
FYI...-1 in the front = +3 in the rear and vice versa.

I've run on my '02...44/16 (stock) good for cruisin only...was crap for the week I spent up at the Dragon.
Last year ran 44/15...OK at the Dragon...quicker on the road, acceptable touring.
Now I'm running 46/15...can't wait to get to the Dragon, 0 - infinity in no time, but our group cruisin 150+ mile loop at 90 - 100mph @ 6.5 - 7k sucks in the florida twistys.
Will be going to 16/46 when the tires done.
 
One aspect of changing the gearing (ratio from front to back on the chain) that I seldom see mentioned or acounted for is the actual efficiency that the engine is working at before and after a change. Even though it may appear that going a tooth larger in the front or smaller in the rear would increase mileage or top end, it very well could decrease mileage and or top end if the engine must work harder because of a loss in efficiency at the speed it is driven. In race vehicles, often the result of a gearing change ends up doing just the opposite of what was anticipated because the efficiency of the engine has moved in a negative direction. This would be far more evident if the same changes were made with a 150 lb rider and then a change in riders to a 250 lb rider. With the lighter rider, the result would more than likely be close to the anticipated one than when the heavier rider was on the bike. The equation gets a lot more complicated as more factors are added and that's what happens in the real life situation.
 
Sprocket Changes

cos_fz1 said:
Everyone rides their bike a little differently. I am looking for input on what different sprockets do to the bike, to decide if I want to change sprockets.

Do you change the actual sprocket size larger or smaller for the front or the back or is it just a change in the number of teeth on the same size sprocket?

What is the impact of replacing the sprocket if you put a larger sprocket on the front or back?

What is the impact of replacing the sprocket if you put a sprocket with more or less teeth on the front or back?

Thanks.
Click to expand...
There is an excellent site which explains every single detail of every possible sprocket combination (including differences in tyre sizes eg. 55 profile as opposed to 60) It Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator.

There are so many possible advantages (and disadvantages) which you'll have never considered, and this shows them all in table format.

An interesting advantage is that by choosing the right combination, you can actually substantially increase chain and sprocket life as the chain will only pass over the same tooth far fewer times. Well worth the look.

I chose what's called a Stage 1 kit which is a 15/45 combination as opposed to the standard 16/44. The advantage here is that you get the best of both worlds. Increased acceleration (easily noticeable) as well as increased top speed. Impossible you say - not so - the reason being that with the standard gearing it will not red-line in top gear whereas now it does which increases the top speed.

The increase in revs is negligible throughout and I've not noticed an increase in fuel consumption. Overall a very worthwhile performance mod for no extra cost (if you are up for a chain and sprocket change anyway that is). Would definitely recommend it as well as using the previously mentioned site to conduct your research.
 
I recently went with a 43 tooth rear sprocket which is down two teeth from the stock 45. So far I have seen a minimal increase in fuel mileage but the bike to me feels a bit more settled and the slight drop in RPM at interstate speeds makes it less "buzzy" and a more capable touring setup IMO.

By the way I went with the Supersprox Stealth two piece rear sprocket and I friggin love it! I don't think it saves much (if any) weight but it sure looks neat!
 
Going to a 16/47 gives an increase of just about 11 % in the ratio.
You gain 2 things:
At the same rpm, you are 11 % lower in speed.
At the same rpm, you ALSO have 11 % more torque...
It does become much more docile for stop & go city traffic.
*provided the tire size remains the same*
 
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