Gear Ratio Theory??

[General Zod]

I need to replace my chain sprockets both front and rear.

What is the rule about modifying gears?

small rear/large front=better top end speed via freeway?
large rear/small front=better off the line speed?

what about:...

small rear/small front?
large rear/large front?



what I dont get is I am told that when you increase by one tooth,...you actually take away from the other sprocket by three teeth?
WHAT THE HELL??????????!!!!!!!!!!WHAT????????????!!!!!!!!du h!!!!?????


MORE IMPORTANT......

my stock ratio is:

16 front
45 rear.

my chain is:

530/104

SO.........if, I change my front sprocket to a 17....
do I have to change my rear OR can I leave it the same? and vice versa?


A-L-S-O ....WHERE CAN I GET SPROCKETS FOR A 1978 GS 400 XC?

[8trackmind]

Go here.

http://www.z1enterprises.com/reference/chainsprockets.aspx

Then here.

http://www.z1enterprises.com/catalog.aspx?pid=GS400XC-1978-MP0

[Tarbash 27]

45 divide 16 gives you a 2.8125 ratio. If you go down to a 42 and a 15. 1 in the front to 3 in the back. You get a ratio of 2.8. So its about the same. You divide the big number by small number to get your ratio. So your 45/16 gearing means the front sprocket spins 2.8125 times for the rear to spin one full rotation. As long as you have the same ratio or close to. The bike would have the same gearing.

[rphillips]

Changing one tooth on the front sprocket will do apprx. the same thing, for the overall gearing, as changing the rear sprocket 3 teeth. If you go up 1 on front & down 3 on rear, the overall will remain appx. the same. What are you trying to do? If there isn't a problem, go back with the orig. set-up

[General Zod]

I see......

Nothing wrong.
I figure I might get a better performance out of a 400..?
I guess I will stick with 45/16?

what does bigger gears do for the bike?
what does smaller geras do for the bike in terms of changing both gears?

Changing one tooth on the front sprocket will do apprx. the same thing, for the overall gearing, as changing the rear sprocket 3 teeth. If you go up 1 on front & down 3 on rear, the overall will remain appx. the same. What are you trying to do? If there isn't a problem, go back with the orig. set-up

[General Zod]

ok.
so now I understand the math part....

45 divide 16 gives you a 2.8125 ratio. If you go down to a 42 and a 15. 1 in the front to 3 in the back. You get a ratio of 2.8. So its about the same. You divide the big number by small number to get your ratio. So your 45/16 gearing means the front sprocket spins 2.8125 times for the rear to spin one full rotation. As long as you have the same ratio or close to. The bike would have the same gearing.

[General Zod]

General Zod thanx you.....

Go here.

http://www.z1enterprises.com/reference/chainsprockets.aspx

Then here.

http://www.z1enterprises.com/catalog...400XC-1978-MP0