First you need to be clear about what you're talking about.
In regular Bike-speak, sprockets go at the rear, and chainrings/chainwheels go at the front.
In BMX-speak, a sprocket goes at the front, and a driver goes at the rear.
If you're speaking BMX, a small sprocket will increase the ground clearance.
Better if you're riding ramps as there's less risk of the sprocket/chain hitting the lip as you drop in.
For speed it doesn't matter, as long as you pick a driver with a suitable tooth count.
If you're not riding ramps, well, a smaller sprocket is still lighter, which is a kinda-sorta advantage.
The downside is that with a smaller sprocket, you will have to use a smaller driver. And the smaller they get, the faster they wear. And the chain wears too.
Small sprockets reduce the weight of your bike so that's always a plus. Also a smaller sprocket doesnt get in the way and they look cooler :)
The recommended size of the chain to use with a small sprocket is typically a smaller chain size to ensure proper fit and function.
Look closly at the sprocket and you will see a small dot or indentation,you align both dots (cam and crank sprocket dots)
Big chainwheel(by the pedals) and small sprocket(at the rear wheel) = big effort. Small chainwheel and big sprocket = small effort
Normally that indicates a worn out sprocket. Replace and you should be OK.
Larrge at the front and small at the rear
well if you have a 8 tooth rear driver you will need a 23t sprocket, if u have a 9 tooth rear driver you will need a 25t sprocket, if u have a 10 tooth rear driver you will need a 28t sprocket, and if you have a 11 tooth rear driver you will need a 30t sprocket
remove bar, chain there should be a small cover over the drive sprocket, held on woth a screw, remove cover, then there should be a screw or bolt holding the sprocket on, remove that, pull old sprocket off, replace it in reverse.
a 9 will do but an 8 would be better
First you need to be clear about what you're talking about.In regular Bike-speak, sprockets go at the rear, and chainrings/chainwheels go at the front.In BMX-speak, a sprocket goes at the front, and a driver goes at the rear.If you're speaking BMX, the most obvious difference is the size, the tooth count.For the same size driver, a bigger sprocket will make the bike slower off the start, but give it a higher top speed.For the same size driver, a smaller sprocket will make the bike quicker off the start, but give it a lower top speed.If you change the driver to match, start and top speed will remain the same, even with a smaller/bigger sprocket. A small sprocket will increase the ground clearance. Better if you're riding ramps as there's less risk of the sprocket/chain hitting the lip as you drop in. If you're not riding ramps, well, a smaller sprocket is still lighter, which is a kinda-sorta advantage. The downside is that the smaller they get, the faster they wear. And the chain wears too.
As far a the sprocket in the front goes, i think they make them as small as 22 tooth, and in the back, it is called a freewheel or a driver. Freewheels are generally larger and drivers are smaller. Drivers can go as small as 8 teeth i beleave.
with a bigger rear sprocket u will be gearing down. therefor u will have better takeoff but lower top speed.