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Rear Sprocket

2K views 5 replies 6 participants last post by  Beach 
#1 ·
Has anyone changed out the rear sprocket for a bigger one?
I have an 18T on the front. But curious what another tooth on the back would do.
 
#2 ·
There has been discussions on this one, by people far better equipped to answer it than me. I remember a chap here made up an Excel spreadsheet that would calculate the RPM difference and (I think) how that would affect top speed.

I just did 18T up front, and kept the stock 43T out back. Recently replaced both sprockets (Renthal) & chain (DID) and did not feel the need to monkey with the rear sprocket. But sprockets are relatively cheap, so why not experiment!
 
#3 ·
KD,

Stock rear sprockets have 43 teeth. So going up or down by one tooth will change RPM at any MPH by a little over 2%. Adding a tooth raises the RPM at any given MPH and feels like more torque during acceleration; reducing a tooth drops the RPM.

A lot of riders like the feel of a larger rear sprocket. You can do a search to see their discussions.

Bern
 
#4 ·
I installed a 44T sprocket on my RS. a GSXR1000 sprocket fit perfectly and at 1/3 the price. but won't fit on the SSSA.

made a noticable difference in drive. not as astonishing as the 18Tfront, but definately smoother and more direct power delivery. Seems more like an electric motor.

a good mod with no downsides.
 
#5 ·
G'day.

I have 18/45 (OEM 19/43) sprockets that were done when I replaced the chain last year. Kinda funny because I already had an 18 front and ordered same but new 18/43.

This dealer has since gone broke? I didn't notice till I was cleaning the bike one day - kero chain clean, etc, etc, and sure enough - it says 45 ( not 43 ) on the back ??

This service was a big one - new P/Diablo tires, front brake pads and all, so I remember thinking the bike feels good, brisk, nice - but did not really feel a big difference in performance or even fuel economy with the 2 more back teeth.

You can feel the front will want to lift a bit easier on hard acceleration in first and second - but I thought that was me not the bike ??

Per the pic below 210 klm per hour at 8000 rpm, and it gets there real quick - with higher gearing I'd get more top speed, but would rather the brisk acceleration, how many times do you ride at over 200 klm p/h anyway..



[ This message was edited by: harrya13 on 2006-09-05 20:36 ]
 
#6 ·
Dropping one tooth on the front is equivalent to going up two teeth on the back. This will give you more acceleration and less top speed. And of course vice versa.

You can work out the ratio from the number of teeth on each sprocket.

E.g. 18t front, 45t rear - 45/18 = 2.5.

So the front sprocket rotates 2.5 times per 1 rotation for the rear spocket.

Changing the numbers doesnt change the ratio much, but one tooth difference on the front or two on the back is very noticeable. Doing both will make a significant difference and make it a lot easier to lift the front wheel, as Harry found out.

Its also one of the cheapest performance upgrades you can do and the easiest to put back if you dont like it, with negligable effect on fuel economy.

Hope this helps,
Brett.
 
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