Bicycle Mechanics - Bought a K2 childrens bike today, questions

Disclaimer: I don't have a micrometer.

So I bought a k2 arapahoe 20'' childrens mountain bike today. Tires held hair so I was riding it around the store, and it seemed mechanically sound, so I bought it. 10 dollars spent at salvation army.

I want to make it ridable for my self. The quill stem appears to be bigger then 1''. What size could it be? (how many different possibilities.) Also, aany body take a wild guess on the seat post size?

Also: What would you guess the rear spacing to be? (Its has a 7 speed freewheel)

I don't have measuring tools.

Has any one ever heard of doing this? Links?

1) Buy a micrometer
2) If the stem is guaranteed not 1" it's 1" 1/8.
3) Rear spacing guess on 7 speed freewheel 126mm.

I said earlier that he should buy a digital-caliper. Now you say a micrometer. Well - go get 'em, Noobert. And my guess is 130mm for the rear dropouts. And buy a tape-measure - measure from the center of the bottom-bracket to the top of the seat-tube. Not the seatpost - top of the tube. That's your frame-size.

Got pictures?

I am not sure about a micrometer but definitly a nice set of vernier calipers. after years of using standard ones and the cross to meteric with me spoke ruler I finally bought a digital set.

my question is are you very petite? why do you wish to ride a bike with 20" wheels?

also are we confusing micrometers with calipers?

http://image.snapon.com/international/pdf/micb103a.pdf

http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=81692&group_ID=1142&store=snapon-store&dir=catalog

I said earlier that he should buy a digital-caliper. Now you say a micrometer. Well - go get 'em, Noobert. And my guess is 130mm for the rear dropouts. And buy a tape-measure - measure from the center of the bottom-bracket to the top of the seat-tube. Not the seatpost - top of the tube. That's your frame-size.
The OP described this as a kid's bike so I expect the 20" refers to the wheel size, not the frame size. Assuming the OP is an adult or at least a teen, I also question why he wants to ride such a small bike. My 9 year old grand daughter rides a 20" wheel Trek kid's MTB and she's small for her age.

Given it has a 7-speed freewheel, I further expect the dropout width is 126 mm.

The stem could be nearly anything as I don't think this thing has a threadless steerer so it could be 1" or 1-1/8" or neither.

A digital or vernier caliper and a decent metric ruler should answer all of the dimension questions.

Bianchigirll: The digital-caliper you've linked to isn't representative of what's currently available. The d-c's available through places like Amazon.com go for $10 and up. They are all the same manufacture. Can $12 digital-calipers be accurate? YES! I calibrated some sets with my $$$ dial-caliper. They are accurate/readable to .02mm.

I want to expierence 20'' multispeed wheels. Ill probally adventually just it for parts, the wheel set should work well on a project some day