Bicycle Mechanics - Trying to determine the headset dimentsion...am I measuring the correct part???

Sorry for the noob ?
Bought a mtb @ a pawn shop for $9
It's a cheap dept. store bike Roadmaster Tracker
One piece crank
Treaded headset
ID of the headtube 1 5/16"
ID of the headset cup 1 1/8"

I thought to determine the measurement for the headset was the head tube diameter.
So is it the measurement of the headset cup?
So will I be able to buy the more common 1 1/8" threadless headset

A 1-1/8" headset cup measures 34.0 mm (1.338" or almost exactly 1-11/32") outside diameter where it presses into the headtube and that diameter is the same for both threaded and threadless headsets. It seems your frame will take a 1-1/8" headset

You paid about $8.25 too much for that frame.

I'd advise against paying actual money for parts to go on or in that frame, also.

Thank you for the knowledge and advice.
I'll go back to checking the Goodwill, pawnshops and garage sales...
I've done some more research I think I know what to look for.

If you bought an entire bike and have stripped it down I would not not bother with any replacement parts unless absolutely necessary. You do not have a 1 1/8 headset, but rather a BMX style headset, which takes a .883" diameter stem and fits a 32.7mm head tube (1 9/32"). A threadless headset is out of the question - different fork, wrong head tube diameter, and a waste of money on that frame in any case.

Your research should start by reading Sheldon Brown pages on any component you are dealing with, for example: http://sheldonbrown.com/headsets.html. You should also be aware that many bike parts are measured in millimeters/centimeters rather than inches, and very accurate measurement is required for some parts (stems, handlebars, seatposts). An inexpensive digital vernier caliper from Harbor Freight or similar would be a good idea. Also FYI threaded parts are always measured by the O.D. of the male part, so the headset thread diameter would actually be measured using the threaded portion of the fork, not the ID of the headset top race.

If you are starting with just a frame then throw it out and start over. Contrary to the belief of some with little experience, building up a bike from scratch is one of the least efficient and most frustrating ways to learn about how to work on bikes - not to mention expensive. Starting with a very low quality, one-piece frame makes it an even worse idea.

Avoid pawn shops, Goodwill, etc - they often have bikes that did not sell (for good reason) at a garage sale. Find a working bike at a garage sale - ride it up and down the street, using brakes and gears. Sometimes one can find a bike on the curb that merely needs a front wheel or other part from a donor bike.

You do not have a 1 1/8 headset, but rather a BMX style headset, which takes a .883" diameter stem and fits a 32.7mm head tube (1 9/32"). A threadless headset is out of the question - different fork, wrong head tube diameter, and a waste of money on that frame in any case.
I'm glad you caught this. From the crude measurements it looked close enough to a 1-1/8" headset's cup OD that I concluded that was the size.

I am with Lester on this. That frame really isn't worth doing much with unless you happen to have a bike with the same style Ashtabula crank that the frame i broken you can use for a donor.

Thank you cny-bikeman and everyone who has responded.
Found this http://bn.craigslist.org/bik/3201700098.html
the guy emailed back said it's available.

Thank you cny-bikeman and everyone who has responded.
Found this http://bn.craigslist.org/bik/3201700098.html
the guy emailed back said it's available.

As I said, building a bike from scratch is not a good way to spend time or money. If you read posts about this topic you will see I have company in that view. Building a bike is not just a matter of attaching parts to a frame. Bikes are far from standardized, although they are slightly less of a nightmare than in the 70's. There are different diameters, distances, angles, shift systems, torques and threadings, all of which have to work together. You will painfully find out that part you bought is not going to work, perhaps after you made it non-returnable, and when you finally get everything installled you will still have to properly adjust it all - which is the only part of the job that is very useful in the long run. An fairly active professional mechanic might do a dozen headset or bottom bracket overhauls in an entire year, so doing one of each on one type of bike is not very valuable.

You will either be paying retail for new parts or be spending a LOT of time scavenging parts that have no labels to tell you if they will work, are damaged internally or bent in a way you can't detect.

Finally, for that frame - the seller has not even told you what model Schwinn, does not know the size for sure, has no headset (one of the hardest parts to deal with) and...why do you suppose it's still "available" after a month? I have a Schwinn Voyager 11.8 frame with fork/headset, handlebars/stem, calipers and seatpost that I will probably sell for about what he's asking for that piece of junk.

I started working on multispeed bikes with a 10 speed Motobecane Mirage I was given as colllateral on a small loan (owner skipped town). The front derailleur and cable needed to be replaced. I had to learn how to choose a compatible derailleur, mount it at the proper height and angle, properly size and cust cable housing, install and lubricate a cable, and finally adjust the derailleur. I learned a lot, and because I paid attention to how things worked on their own and together I learned about more than just the derailleur. Likewise if you pick up a bike that's basically rideable but needs some cleaning and adjustment you will find yourself with more than enough to learn, and a bike you can get on the road safely without spending months on it.

As I said, building a bike from scratch is not a good way to spend time or money. If you read posts about this topic you will see I have company in that view. Building a bike is not just a matter of attaching parts to a frame. Bikes are far from standardized, although they are slightly less of a nightmare than in the 70's. There are different diameters, distances, angles, shift systems, torques and threadings, all of which have to work together. You will painfully find out that part you bought is not going to work, perhaps after you made it non-returnable, and when you finally get everything installled you will still have to properly adjust it all - which is the only part of the job that is very useful in the long run. An fairly active professional mechanic might do a dozen headset or bottom bracket overhauls in an entire year, so doing one of each on one type of bike is not very valuable.

You will either be paying retail for new parts or be spending a LOT of time scavenging parts that have no labels to tell you if they will work, are damaged internally or bent in a way you can't detect.

Finally, for that frame - the seller has not even told you what model Schwinn, does not know the size for sure, has no headset (one of the hardest parts to deal with) and...why do you suppose it's still "available" after a month? I have a Schwinn Voyager 11.8 frame with fork/headset, handlebars/stem, calipers and seatpost that I will probably sell for about what he's asking for that piece of junk.

I started working on multispeed bikes with a 10 speed Motobecane Mirage I was given as colllateral on a small loan (owner skipped town). The front derailleur and cable needed to be replaced. I had to learn how to choose a compatible derailleur, mount it at the proper height and angle, properly size and cust cable housing, install and lubricate a cable, and finally adjust the derailleur. I learned a lot, and because I paid attention to how things worked on their own and together I learned about more than just the derailleur. Likewise if you pick up a bike that's basically rideable but needs some cleaning and adjustment you will find yourself with more than enough to learn, and a bike you can get on the road safely without spending months on it.


Interesting...

Is it worth overhauling a cheapo bike? I've been told that I'm better off buying a new one...

Uplah