Rule of Thumb for rear sprocket change??

[MO350X]

Hey folks,
What is the rule of thumb for sprocket tooth count change on the rear sprocket?
I am accustomed to front sprocket changes but the rear has different math, right?
Meaning even a single tooth change at the rear sprocket is like more than one tooth change on the front sprocket, right?
My situation is going from 39 tooth to a 38.
I can tell you from experience that it makes taking off in 1st gear feel like taking off in second!

Hope that all made sense. :)

Thanks for any and all help.

[bigyellow4x4]

wrong changing 3-4 on ther rear is like changing one on the front the more count the slower more torq you get

[MO350X]

I didn't realize it took THAT many teeth change in the rear to make only one tooth's worth of change on the front.

[Wickedfinger]

you have it backwards

[Wickedfinger]

you have it backwards. Look at it from a 10 speed bike point of view and you'll get the math.

[MO350X]

Yep, I thought changes to the rear sprocket made more of a difference than that.
Thanks for clearing that up.

[TimSr]

One tooth on the front equals about 3 1/2 teeth on the back. Bigyellow4x4 has it exactly right. If you change the rear by one tooth, you probably wont notice the difference.

Adding to the front gears up. Adding to the back gears down.

[ATCnut]

The other thing to remember about rear sprocket changes is you have to be able to tighten the chain. Usually you change the rear by 4 teeth. This makes a chain that is two links (barrels) shorter or longer work with the same adjustment. If you visualize that the chain only goes on half of the sprocket it works out.

[Oldshell4481]

so if i wanted to make my big red not revv so much at higher rates of speed i should get a bigger front sprocket?

[freewheel3]

so if i wanted to make my big red not revv so much at higher rates of speed i should get a bigger front sprocket?
Yes, that is correct.