let's talk sprockets

Hey everyone, I'm in the big middle of building a Skyhawk bicycle frame w/ a 48cc 2 stroke. I'm still in the process of building the actual bicycle right now and I've made some good progress. Having never built a bicycle before, the learning curve has been steep. I thought I could transfer everything over from a Schwinn cruiser, and I was way wrong. So what I ended up with is parts from a couple different bikes all mashed in to one. The front forks are mountain bike "shock" forks, cruiser handle bars, cruiser one piece pedal crank, and mountain bike wheels with cruiser 2.125" tires. So far it looks good.

One thing I'm a little unsure of is the rear sprocket. The mountain bike's rear wheel is a 7 speed freewheel. What I want is a single speed freewheel. One person suggested a bmx single speed freewheel.

I guess my real question is "how will I know it fits when placing my order?". What I currently have is a freewheel that uses an FR1 style tool for removal.

http://www.amazon.com/gp/product/B001B6RGXG/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=AJ5KCH6R81QUN

And the freewheel looks somewhat like this one:

http://www.amazon.com/Shimano-Tourn...=1429840912&sr=8-3&keywords=shimano+freewheel

So do I HAVE to get one that uses the same tool to fit on the axle? Or can I get a different style, but single speed, freewheel and it threads on the same?

I only ask because I'm finding out more and more that not all bicycles are made the same. Different size/styles on lots of components such as seat tubes, fork tubes, rear axle widths, etc.

Thanks in advance.

And something like this is what I want to convert it to:

http://www.amazon.com/Shimano-Tooth...2879&sr=8-1&keywords=shimano+single+freewheel

Thanks again knightscape. Bullet dodged. I also didn't know (surprise) that more than 1 type of bicycle chain exists. I broke out the caliper again and measured the crank sprocket and the freewheel sprockets. Once again, they're different. Yep, 3/32" for the mountain bike freewheel, 1/8" for the Del Mar crank. Explains why when I tried using a 1/8" chain that it popped like **** and kept falling off.

Another step up on that learning curve!

I think the 3 piece crank is going to happen. It needs to be wider so the pedals can clear the exhaust anyways.

Sorry guys, it's staying as a single speed cruiser. I don't want it cluttered up with more crap than it needs.

I got my single speed freewheel from a great little bike shop here in Charleston. It's an 18t as opposed to the 19t the Del Mar had, so a very small increase in pedal effort, but overall I'm very happy with it.

To put some myths to rest:
-I'm not going to rely on the bike to get me anywhere important with a deadline. It's purely recreational.
-There are hills and grades here in the Charleston area.
-The little 48cc needs no help getting up them.
-The bike probably weighs all of 40 lbs.
-I am thoroughly impressed with the bike I have built here, exactly the way I built it, and wouldn't change anything.
-If, for whatever reason, I find myself needing more gears in the future, I can always install them later.
-If I run out of gas, I carry an aluminum bottle with another 1/2L of fuel.

Bob Saget... I forgot to add a picture.

The yellowed plastic crap is gone now. Much cleaner without it.