[Nico]

I have seen a few posts recently about speedo correction factors and gearing so I thought I would post up a chart that shows exactly what percentage error you will have for a given sprocket size.

If you have no idea about what gearing you would like and how it will affect your bike it is also worth noting that the percentage in the chart can be applied to your top speed and RPM for a given speed.

A couple of examples:
If you used to run at about 5.5k rpm doing 80kph and you do a -1/+2 conversion on your 03 your new rpm will be about 6k rpm (10.4% increase)
If your top speed was 167mph on your 03 and you do the -1/+2 conversion you new top speed will be around 150mph (10.4% decrease).

The math to work this out for yourself is nice and easy, here is the equation:

% = 100 * (A - B) / A

Where A is the stock gear ratio, A = (# of front teeth / # of rear teeth)
which for your 03 -06 would be (16 / 43) = 0.372093
and for your 07-10 would be (16 / 42) = 0.380952

Where B is the new gear ratio, B = (new # of front teeth / new # of rear teeth)


I have also attached the spreadsheet this screen capture is of if anyone is interested, you just have to unzip it.

Hope someone finds this helpful.

I thought I'd add this post from rr3 just for a little more info on gearing ratios and the like:

I think most of this has been covered in the various other threads on this topic but, here we go:

What will each type of change do?

Generally speaking:

If you drop teeth on the front sprocket, or go up teeth on the rear sprocket, then it will give you greater acceleration.

If you go up teeth on the front sprocket, or down teeth on the rear sprocket, then it will give you a higher top speed, at the expense of worse acceleration

A change of one tooth at the front is roughly equivalent to going almost three teeth, in the opposite direction, on the back. e.g. -1 at the front is almost equivalent to +3 on the rear.

If you go -1 at the front and -3 on the rear then its really a waste of time and the change will, to a certain extent, cancel each other out.

Here is a useful website where you can input your bike and it will show you the effects of just about any gearing change you can dream up.

www.gearingcommander.com

Does it give me more horespower?
Changing your gearing doesn't give you any more hp, it just plays about with the rpm you'll be running at certain speeds, in certain gears (you can move the power to where you need it).

Type of Sprockets:
Front sprockets will always be steel. Usually, you will have three main choices of rear sprocket material:

- Aluminium
- Steel
- Hybrid (steel teeth/aluminium centre)

Steel sprockets should be more durable, at the expense of being a little heavier with less efficient power delivery to the rear wheel (more mass for the engine to turn).

Aluminum sprockets are said to be less durable but are much lighter than steel, allowing more efficient power delivery to the rear wheel (less mass for the engine to turn).

Hybrid sprockets attempt to offer the middle ground between the two; providing good durability and a reduction in mass over an all steel rear sprocket.

Chain:
If you are changing your gearing then it makes sense to change your chain at the same time. Using an old chain on new sprockets can increase wear. In any event, your old chain may not be long enough for the new sprockets anyway.

Side effects:
If you change your gearing then it will mess up the calibration of your speedo and, therefore, your odometer.

This can be fixed by purchasing and programming a corrective device like a Speedohealer, or SpeedoDRD.

You can work out the exact calibration value using a radar gun, dyno or, if you are of a masochistic ilk, speed cameras/police officers!

There are also tools on the following websites where you input the details of your bike and the gearing changes and it will give you a calibration value to input into your chosen correction device.

SpeedoDRD; or
Speedohealer

Another side effect of gearing changes is that, by chasing acceleration, your fuel consumption may suffer (You will be higher in the rev range more often).

Most common changes for a CBR600RR:
The most common change of gearing for the CBR600RR has to be going down one tooth at the front sprocket and up two teeth at the rear (-1/+2). This gives a noticeable increase in acceleration whilst still maintaining a reasonable top speed.

520 Conversion?
Many users will also convert to a 520 pitch chain and sprocket set ("520 conversion"). The bike comes stock with a 525 pitch chain and sprocket set. You can only use a 520 pitch chain with 520 pitch sprockets and you can only use a 525 pitch chain with 525 pitch sprockets.

The main reason for going to 520 pitch is that the chain, in particular, will be smaller and lighter. This reduces the rotational mass in the drivetrain. The theory is that this will allow a greater transmission of engine power to the rear wheel, as less energy is sapped in turning the chain and sprockets themselves.

Some fear that a 520 pitch chain is too small and weak to handle a 600cc sportsbike. The quoted strength of the higher quality 520 pitch chains is, however, more than enough to actually handle most 1000c bikes, let alone 600s.

 

[DeathWish]

Great chart. Pretty on-par with what I have found with my -1/+2 gearing. This doesn't take into account speedo inaccuracy from the factory, which while worse on bikes like Ninja 250s where the speedo sensor is on the front wheel, it can still be +/- a few % off.

 

[Nico]

I wasn't aiming to account for factory error margins, just those created by changing sprocket sizes from standard.

 

[MikeyP]

This should be made a sticky!

 

[Nico]

Thanks mate!

 

[cichlid_baby]

If I remember correctly... I think I have read many times that the factory speedo error is about 5%-10% faster than actual GPS readings.... also that the factory error is done intentionally especially on bikes.

I don't know for sure since I have not tried testing my bike with a GPS yet.

 

[Nico]

5%-10% sounds about right, but it will vary depending on how worn the drive train is so personally I'm happy to leave the factory error in there. Might get out the gps and see how far out it is though - job for tomorrow

 

[v-tec crx]

with my 15/43 (-1, +1) on my 07rr

the GPS reading was 88kmh when my speedo said I was going 100kmh

that is a -12% difference...

just to give an idea on the factory speedo error

 

[Nico]

3% from factory isn't bad...

 

[05'Scorpion]

Good post thanks Nico

 

[haf2race]

Is there anyway to recalibrate speedo once you do a sprocket change?

 

[tenjin]

Is there anyway to recalibrate speedo once you do a sprocket change?

thats what the speedo healer / speedo drd are for.

 

[dkeets]

I just cal'd my 06 -1/+2 with GPS and mine was of by -17%!

 

[05'Scorpion]

I just cal'd my 06 -1/+2 with GPS and mine was of by -17%!

sounds about right man...mines gotta be off by about that much...doing it tonight.

 

[dkeets]

sounds about right man...mines gotta be off by about that much...doing it tonight.

Hope you have better luck then I did today when i did mine. I got stuck in a sick down pour on the way home that came from no where! I was freaking out since I did the ram air MOD and thought water for sure was going to get into my intake!!! And the GPS I used was a little jumpy so I had to work really hard to maintain 60 on the road...

 

[tenjin]

Hope you have better luck then I did today when i did mine. I got stuck in a sick down pour on the way home that came from no where! I was freaking out since I did the ram air MOD and thought water for sure was going to get into my intake!!! And the GPS I used was a little jumpy so I had to work really hard to maintain 60 on the road...

while not 100%

i used the bike speedo as the "hold it" at mark, did 60 on bike held it there, did some math, found that 60 mph on gps would be roughly 72 mph on the bike

held 72mph on the freeway, and sure enough, boom, i had 60 on gps, went home used my numbers and setup the speedo drd, am now within 1mph of gps at all times.

 

[TribalCBR06]

Very useful chart. Thanks for sharing

 

[dkeets]

while not 100%

i used the bike speedo as the "hold it" at mark, did 60 on bike held it there, did some math, found that 60 mph on gps would be roughly 72 mph on the bike

held 72mph on the freeway, and sure enough, boom, i had 60 on gps, went home used my numbers and setup the speedo drd, am now within 1mph of gps at all times.

That's about what I found. Mine showed 73 while at 60.6 on the gps... Haven't had a chance to check it but sounds like I don't need to now.

 

[05'Scorpion]

Did a side by side with my buddy on his 954 which is pretty accurate....Im within 2 mph or so at any speed...any way to correct this last little bit so its dead on at every speed?

 

[dkeets]

You will have to get a GPS but even then it won't be spot on due to the rounded speeds your speedo shows. A GPS will give you decibel values where as your speedo just gives you whole numbers which have to be rounded to. There for exact accuracy is I'm possible unless you have a radar detector and a GPS with both showing decibel values... So moral of the story is that 1-2 mph's off is pretty good and going more in depth isn't really worth the trouble(in my opinion anyways)...