Kawasaki Sportsbike Riders Club - Australia - Online Forum

I've actually scrounged enough cash together to get my new cahin and sprockets. Some people say that 14 on the front (of a zx6r) puts stress on the output and you should go up at the rear, but all the quick accelleration kits are 14/40. Does anyone know of any proof that the output does get stressed or is it an old wives tale?

Aussie Ninja wrote:I've actually scrounged enough cash together to get my new cahin and sprockets. Some people say that 14 on the front (of a zx6r) puts stress on the output and you should go up at the rear, but all the quick accelleration kits are 14/40. Does anyone know of any proof that the output does get stressed or is it an old wives tale?

I think the main reason for changing the front rather than the back is because you don't 'have' to swap the chain for a longer one. If you are going to be changing the chain anyway (which you should) you might as well go for a different rear instead.

Don't know if it will fit but I have a brand new 14 front and a 44 rear set of renthal sprockets in light weight 520 size.... They fit a zx9 and quite a few other models....

Rear is a renthal 184 and the front is renthal 321...

mr madkaw

how much $$$$$$$$

fab

I went a 14 front on mine and for 27bucks it did the trick, now if you need a new set you may as well go the 15/43 but if you dont just go the front sprocket its cheap and it works and if you have to go for a long ride somewhere you can just pop the 15 back on.

MadFab wrote:mr madkaw

how much $$$$$$$$

fab

For you... ummmm $500, then we'll be square...

Not sure what there worth these days, make me a reasonable offer....
and I said reasonable not like the ones you started with on the zx9r..

Aussie Ninja wrote:Does anyone know of any proof that the output does get stressed or is it an old wives tale?

It's not an old wives tail, it does load the chain up more because you're decreasing the radius. I could post the math up if you're interested, but basically it's bugger all, the extra load just happens to be the same % wise as the ratio change.

So if you go from a 15 to a 14 that's 7.1% increase on chain pin loading. I don't know how it translates into chain wear though, does that mean if you got 20,000km out of a chain you now could expect 18,571km out of the chain.

Plus you're also turning the chain through a tighter radius. Mustn't be an issue with your bike, but smaller fronts can cause swingarm guides to wear out faster too.

There is one disadvantage of going up on the rear, it's more unsprung weight and great rotating mass. So take your pick

(Me, I decided on the largest rear I could use with the OEM length chain (+2) as I did it very early in the bikes life and didn't need a chain change, it also means I lost about 1" of wheelbase.)