Metacortex

I believe Schwinn started using the -x model number suffix in 1959 to indicate the type of rear hub desired on a dealer order. The -9 designation indicated a derailleur hub. Note that these codes were only applicable to models where different hubs were optional on a given bike. When a specific hub was the only available option the -x designation was redundant and not normally used. In other words since a 1974 P10 was only available with a derailleur hub it was not necessary to use the -9 designation when ordering. You can see an example of some of the hub ordering suffix numbers on the 1963 dealer ordering instructions here:



Here are some other examples from the 1970 consumer catalogs:

fleslider 

Thanks guys for the advice, I will get a set of Pasela's when money is not so tight, i had these Kenda's laying around so i decided to use them.
As for Tubulars, i think with this bike i will keep with these original wheels. I have the Pro that needs to be done and it will have tubulars. along with the Trek TX900 that i have will get tubulars also. but although i do have a spare set of tubulars with low flange Campy's i could use on it..hmmm a thought.

Wildwood 

Regarding tubular tires, the more expensive ones really make a difference. My learning experience has been Vittoria Rally, Conti Sprinters, Specialized Turbo, Veloflex (Roubaix, Arenberg, Valaanderen), Schwalbe S-1. I want to try the newest Vittorias. I glued (or reglued) several pairs earlier this year.


The Vittoria Rally has a bad rep but at about ~$15 from UK vendors there isn't much risk. Usually takes 3 to get 2 without a lump, but I still have a good pair mounted that refuse to die. The cotton casing is thick and gives a damped ride. I think Rally is available in 25mm, in the past i think they were just 23s.


Conti Sprinter is a good step up. Mine are 22s, the newer ones may be 24s. They give a more race feel pumped to 110psi for my 200# body. Sharp, solid - not the damped ride of the Rally. Never tried the Sprinter Gatorskin as I disliked clincher Gatorskins.


Specialized Turbo is strictly a race tire and durability may be less, but I do like them. 24mm, i think.


Veloflex has become my favorite. Pump them hard for a race feel that's still smooth or slightly less pressure for a sublime Sunday afternoon ride. The 28mm haven't been mounted yet, but 25mm seems wide enough for any pavement condition.


The Schwalbe is 30mm and my light off-road tire. So far they have proven tough enough for gravel, but lack suppleness on pavement - which is the trade-off I wanted.

exmechanic89

I really dig those Schwinn tandems in the catalog scan above.

qcpmsame 

The Vittoria Rally are available in both 23 and 25 width, and you can indeed find them for $15.00-$16.00 from Wiggle and at times at Ribble. I didn't have quite the odds you reached @Wildwood, I was approaching the 4 to find 2 without either a lump in the casing or get punctured by a tiny sliver of gravel or rock cut first time out.

When I had a decent pair glued up it was respectable riding, especially if I dropped the pressure down around ale 90 psi. But any lower just invited a puncture that I got to repair and resew the casing. I am sure I am doing something wrong but the Giro are doing fine for me. I can find them for $20.00 on sale at eBay vendors, occasionally. Long term I hope to squirrrel away the coins to buy some of the Veloflex Corsa Graphene sew ups. Won't be any time soon since I am being retired here shortly.

Bill