This info applies to Chicago made Schwinns. Lugged frame imported Schwinns are not covered here.
If you're looking for the largest amount of Schwinn information in one place, check out the Tech & Spec 1.3 on the 'Reference Books' page. It's the largest and most comprehensive book on vintage Schwinns ever assembled. If you really enjoy the old Schwinns and want to know more, this book is for you.
Schwinn used their own special rim sizes on many bikes. Schwinn rims have knurling (hash marks) down the center and are often stamped with a size designation like S-7 or S-5. Sometimes wheels got replaced with with non-Schwinn wheels, so check to see that you still have the original Schwinn rims on your bike before purchasing tires.
27" wheel Schwinns, Varsity, Suburban, Continental, etc.
27" wheel Schwinns used a standard 27" x 1 1/4" tire. The steel S-6 27" Schwinn rim is the only S-6 rim that takes a common tire. With stock Schwinn rims, it's usually advisable to only top out the tire pressure at 70psi, regardless of what pressure the tire is rated to. At higher pressures, tires tend to creep of the steel (and bead-less alloy) rims that Schwinn (and most other manufacturers in the 70s) used on their bikes.
26" Skinny wheel Schwinns, Racer, Breeze, Collegiate, etc
Schwinn Lightweights like the Breeze, Racer, and Collegiate used S-5 or S-6 rims, and are most often found in the 26" wheel size. (S-5 and S-6 26" rims are the same size, just the cosmetics are different.) These came with Schwinn-specific 26" x 1 3/8" tires with a Bead Seat Diameter (BSD) of 597mm. Non-Schwinn skinny wheel 26" bikes use a similar-looking but physically smaller wheel that takes a 590mm BSD tire. That 7mm makes all the difference between a tire that fits and a tire that doesn't. (It should be noted that lugged frame imported Schwinn "Collegiates" from the 80s used a standard non-Schwinn sized tire.)
Kenda makes tires to fit the 26" S-5 / S-6 rims, available in blackwall or gumwall. (I recommend blackwall, much more durable.)
24" skinny wheel Schwinns also used a special Schwinn-specific tire size.
20" skinny wheel Schwinns use an unusual tire size, but one that is still in common use on speciality bikes like recumbents. The Fastback and Stardust (as well as other Schwinns that used S-5 or S-6 20" rims) use a 20 x 1 3/8" tire with a Bead Seat Diameter (BSD) of 451mm.
26" Middleweight Schwinns, Typhoon, Corvette, Hollywood, American, Tiger, etc
Schwinn's Middleweight cruisers used S-7 rims and 26" x 1 3/4" tires (not the same as 26" x 1.75"). These S-7 rims take a special Schwinn-specific sized tire with a 571 Bead Seat Diameter. (Standard 26" tires and rims have a BSD of 559mm, a big difference.) Kenda makes tires to fit the S-7 rims, the best ones are 26" x 2" x 1 3/4". These come in blackwall or whitewall, both are decent.
The S-7 size was also made in 24" and 20". These also take special Schwinn-specific tires. The Sting-Ray line in particular used S-7 rims up front. The Junior Sting-Rays also used an S-7 in the back. Tires are available for the 20" and 24" S-7 rims, although these aren't as nice as the 26" size and are usually only available in blackwall.
26" Heavyweight / Balloon. Phantom, Spitfire 5, Cruiser, etc
Schwinn's Heavyweight line-up used S-2 rims. These rims take standard tires. The BDS is 559mm. No need to search around for a special size. The stock size was 26" x 2.125", but you can use a 1.95" with no problem.
Even though Schwinn bikes often used special rims and tires, you can use standard tubes with no problem. Tubes stretch, tire beads do not.
For 26" wheel Lightweights you can use standard 26 x 1 3/8 tubes.
For 26" wheel Middleweights you can use 26" x 1.75" tubes.
Many parts are standard and are commonly available at bike shops. The pedals are standard 1/2" pedals. The chains (except for the skiptooth style) are still made, 1/2" x 1/8" for bikes with a single cog in the back, 1/2" x 3/32" for derailleur models. Brake cables are still the same. Brake shoes are standard (Kool Stop Continentals are recommended, although you'll have to file a bevel in the face so they work great from the get-go.). Tubes are standard.
Specific parts are available through eBay. You might also want to check the Classic Classified section of the Schwinn Forums or Memory Lane Classics (see my Kool Links page for a link). Local and regional swap meets are another great place to find parts.
Schwinn parts are generally not year-specific as a matter of function. Some folks (myself included sometimes) like to get correctly dated parts for special Schwinns, but for the most part it doesn't matter what year the part is. Schwinn didn't make yearly changes to much of anything besides paint colors. It should be noted that '65 and earlier stems are a larger diameter than the '66 and later stems.
Most decals for Schwinn bikes have been reproduced. Chainguard decals, top tube decals, seat tube decals, almost all different varieties are available in reproduction. True NOS decals still exist and are available, but these often crumble under the slight sliding force of application.
The two best sources for reproduction decals (at least in my opinion) are Memory Lane Classics and Vintage Schwinn ( www.vintageschwinn.com/decals.html ). Memory Lane has a greater selection, and is the sole source for the King Size American chainguard decal. Vintage Schwinn has a wide selection and easy click-to-buy checkout. Both are reasonably priced.
The serial number on your Schwinn will tell you when it was made. The serial number is either on the underside of the bottom bracket ('52 and earlier), by the left rear axle (through mid '70), or on the head tube (mid '70 and up).
The folks at Old Roads (see the Kool Links page) have a Schwinn serial number chart on-line. These charts have been published in various books as well.
The serial number will only tell you when the frame was made, it won't tell you what model it was.
If you're missing the chaingaurd, or your bike has been repainted, then it's going to be too complex to explain here. There's lots of factors involved: year of manufacture, paint color / style, chainguard style, fender style, stem style, sprocket style, accessories / accessory marks. I guess I could create a flow-chart, but it would fill a book.
Post a picture on the Schwinn Forum ( www.schwinnbikeforum.com ) and it'll get sorted out.
Repainting is tempting, but it's often-times a bad idea. Let me elaborate.
Collectors prize original paint, even somewhat worn original paint. So a bike with halfway decent original paint if going to be more valuable than a repainted one. And in recent years the concept of "patina" has become a big thing, essentially valuing an honest time-worn finish as a good thing.
Some Schwinn colors on particular models are particularly deriable. Flamboyant Lime and Terra Cotta Sting-Rays come to mind. Original paint on rare models is also desirable. A Phantom with somewhat worn original paint is going to be valuable, and a repaint (unless it's automotive quality and restoration accurate) will diminish the value.
And the original Schwinn finish is very durable. Unless you're a professional or experienced painter, you're not likely to be able to get a hard and durable finish with a repaint. Using $5 spray paint? It's going to scratch and mar easily.
But on the other hand, there's lots of common Schwinns out there with rough paint that have no particular collector value. Want to paint up a '70s Typhoon or Hollywood? Have at it. Frame has already been repainted? Have at it.
Hard to say. Most of these old bikes aren't worth more than $100. Only a small percentage are real collectables. Just because an old Schwinn isn't considered a collectable doesn't mean that it doesn't have value. Many of these old Schwinns still have value as a functional (or potentially functional) bicycle. Oftentimes a member of the general public will be willing to pay more for a common model Schwinn than a collector.
The most collectable Schwinns are typically: men's models middleweight or heavyweight, tank models, excellent originals, early Sting-Rays, Stik-Shifter equipped Sting-Rays and derivatives, models that came from the factory with fancy equipment.
Schwinns that typically aren't particularly collectable: women's models (Breeze, Hollywood, etc), lightweights (Varsity, etc), basic bikes with no extra equipment, worn condition, 70s era bikes (except Krates and the like).
Post a picture on the Schwinn Collectors Forum if you want to know more. You can also search completed auctions on eBay for your particular model to get a general sense of what your bike might be worth, but do keep in mind that eBay prices are sometimes inflated and that such prices are difficult to get locally.
There's a lot of differing opinions on this topic. For painted surfaces I typically don't do any more than carefully wipe with a damp cloth. Be very careful around decals and chainguard screens, as these are often fragile and can be wiped away with the aforementioned damp cloth.
For chrome, I use #000 steel wool and spit, and then wipe down with a shop cloth towel. Others recommend brass wool, as it doesn't rust and is thought to be better for chrome. There's also a product called Joe's Moonshine that removes rust from chrome. And there's other products as well.
The ultimate goal in cleaning the chrome is to remove the rust without scratching the chrome. If you use a coarse steel wool, or a Chore Boy pad, or similar, then you will scratch and dull the chrome. This sort of damage is hard to fix, and greatly reduces the value of the affected parts.
Well, you'll want to clean out all the bearings, repack them with fresh grease, re-assemble and properly adjust. This would include the front hub, the rear hub, the fork bearings (headset) and crank bearings (bottom bracket). Regreasing all the bearings is commonly known as an "overhaul". Many bike shops offer an inexpensive "tune-up" service. A tune-up is a minor service and will not address the main problem with the older bikes, which is that the original bearing grease has dried up and the bearings are running dry. Running a bike without grease is somewhat like running an automobile without engine oil. So spend the extra money and get all the bearings re-greased.
You'll also want to make sure the wheels are true and round. Fresh tires are always a good idea. Fresh brake pads are almost always needed, and these take a bit of skill to install and adjust properly. I highly recommend Kool Stop Continentals as replacement brake pads, although you will have to file a bevel in the surface to match the profile of the rim, it takes only a few minutes and the increased braking power is well worth it. And if your bike has gears, you'll want to make sure they are correctly adjusted.
Often I'll replace the pedals with modern ones that look somewhat vintage. Many of the low and middle end Schwinns used pedals that did not age well, or had blocks that rotate easily. Replacing crusty pedals with smooth new ones makes a huge difference in how an old bike rides.
The old seats are often times not that comfortable. A comfy retro-style seat is a nice improvement.
If the chain is rusted or worn, you'll want to replace it with a new one. This is especially true with coaster brake bikes. If the coaster brake is the only brake on your bike, you'll want to make certain that you have a decent chain. The stock chains on these old Schwinns were high quality, so if you have a decent low-miles original bike, then likely the chain is fine.
By the time you add up parts and shop labor, it will usually take around $200 to make an old geared Schwinn ride factory fresh again. A coaster brake version may cost $150 to have properly serviced and replace worn parts.
Funny you should ask. I wrote a pretty decent 600 page book on Schwinn bikes: Schwinn Tech & Spec 1.3. It has more info than you can shake a kickstand at. It's currently available on my "Reference Books" page. Click over and check it out, it's by far the most practical Schwinn reference book ever assembled.
The Schwinn Forum (linked on my 'Links to Kool Stuff' page) is a good place to seek mechanical advice.
And the Glenn's Complete Bicycle Manual is a decent book from the 1970s. These show up from time to time on eBay, and sometimes show up at used book shops. It's not Schwinn-specific in all things, but does have a good amount of Schwinn how-to.