i bought a 30t sproket (macneil) for my bike and the freewheel is still the same as it was for my 39t sproket and i have to pedal really fast. Do i have to buy a smaller freewheel or what and if so, do i need a freewheel removal tool?

Well, basically you're an idiot for buying a sprocket that is too small for any freewheel.

its not too small for any freewheel, apparently a 11t freewheel will fit it

11 t freewheels don't exsist. You need to buy a cassette hub and get an 11t driver for it.

what is a driver?

A fancy name for a cog.

No, a driver is a single machined piece, whereas a cog is just a ring with teeth, and is locked into place with a lockring.

Functionally, what is the difference?

The benefit of a driver is for freestyle riders: they require almost no maintenence; you put it on there, and you never have to tighten it or anything.

The benefit of having cogs is for racers, so that they can very quickly swap their gears; basically, it's the same idea as having a spider up front.

that sounds good, how much?

You'll need about $175 for a decent new back wheel, minimum. About $100 for just the hub, spokes, and driver if you know how to lace a wheel to you old rim, which I'm fairly certain that you're not capable of doing.

ive seen a alex supra g rim with an eastern 11t casette driver and spokes for (im not sure about dollars, im from england) 70 pounds

is that good?

No, not really.

edit: Although, I'm sure that it'll be fine for the average nibbler.

whats that supposed to mean?

Ask Jeeves.

good one

Hahaha, that's great.

I saw a commercial about ol' jeeves today.

he doesnt need an entirely new wheel. he can just switch out the hubs and keep the same rim.

Ahem.

Cassettes with separate cogs and lockrings still have drivers (just like freecoasters), that's the part that the cog slides onto. one-piece machined cog/drivers came into being because teeny tiny nibbler gears up front mean even teenier rear cogs and the drivers for existing cassettes wouldn't take 9t cogs...the driver is physically larger than the cog would have to be. One-piece units are a workaround so companies didn't have to invent a smaller driver standard or heaven forbid a new cassette. The other issue was durability...racers usually don't run compact sprockets, which means the cogs are larger, thicker and wear longer. The fewer teeth you got wrapped around a standard sized driver body, the thinner that cog gets and the more likely you are to wear it out or snap it.

Thanks Snazzy. That's why my cruiser came with 39/16. Saving weight would only result in compromised reliability. I broke a chain once already while racing. Don't need any more broken drivetrain components.

sorry Beerman, i missed that.

And you're not saving *that much* weight with compact gearing...a handful of grams at best. Flatlanders were the first to demand tiny gears 'cause it kept their sh*t small and out of the way. Street and park riders jumped the bandwagon for that reason, and additionally because a smaller sprocket is harder to bend laterally when you smash it against concrete ledges or steel coping.