I'm quite new to track racing and have been given a terry dolan track bike to start off. Only problem is the gearing. I have a miche sprocket on at the moment and would like to go from a 16 to a 15tooth. Question is can i use any sprocket or do i have to use a miche one.
The easiest thing would be to use a Miche one. These don't screw on like regular sprockets but instead fit onto an adapter which is in turn screwed onto your hub. You'll have an adapter on there already with the 16T. To change sprockets with this system you just need a lockring tool to remove the lockring holding the cog on.
You can also use regular screw on sprockets but you'll need to remove the Miche adapter first before you can use them. To change these types of sprockets you'll need a lockring tool and also a chainwhip to unscrew/tighten the sprocket. You'll need these same tools to remove the Miche adapter.
If buying regular screw on sprockets I'd recommend the Dura Ace ones as they're high quality, easily available and cheap (in the UK at least).
You can pretty much use any cog you want so long as the width is compatible with your chain (probably 1/8"). The Miche cogs use a special adapter as mentioned above but the adapter just threads onto the hub like a normal cog would so if you remove the adapter you can use whatever. It would probably be more convenient to use a Miche cog though so you wouldn't need to remove the adapter.