Campagnolo dating codes
Sun Tour was the world's leading innovator in bicycle componentry in the 1970s and brought real respect to Japan, but was eclipsed by Shimano in the late 1980s.
This article describes some of Sun Tour's technical advances, and offers information on maintenance of some Sun Tour components.
On some bottom brackets there are two codes: one indicating the maker of the main triangle and the other for the maker of the rear triangle or perhaps the person who cut and shaped the tubing, if not done by the framebuilder.
If you know which mark was used by a particular craftsman, please let me know.
I used to regularly modify Regina and Atom freewheels by re-grinding the teeth of the sprockets so that they somewhat resembled those of Sun Tour or Shimano sprockets...a treatment later known as "Sheldo-Glide." [And I found that this modification only worsened the tendency of a 7- or 8-speed chain without protruding rivets to slide along.
In the case of some early 80s Treks, the number is under the plastic cable guide on the bottom of the shell.
The large sprockets of some Sun Tour freewheels also sometimes had teeth alternately bent slightly toward the left and right, to aid in chain pickup.
It was possible (and not unheard-of) to assemble Sun Tour freewheels with some of the sprockets backwards, markedly degrading shifting performance.
Late 1982 the first Series-III based bikes rolled out the 600a & 700. Also some bike owners may confuse the year of the date it was originally purchased with the model year which in some cases could be different**340790 1980 Redline Proline (PL-20)341692 1978-80 Proline (has No gusset behind seat, No Redline stamp)343277 1979 Redline MX-II (has No gusset behind seat, No Redline stamp)348647 1982 Redline MX-II (600 or 700) Frameset.
Here is how to tell if you have a MX-II or Series-III based frame. 349470 Unknown Year Redline MX-II or III350291 1981 Redline Proline 2 (had No gusset behind seat, & No CS bridge)350294 Unknown Year, Redline Proline354065 Unknown Year, Redline MX-II357485 Unknown Year, Redline Proline (No CS bridge)363127 Unknown Year, Redline Proline (Redline Oval stamp)375830 Unknown Year, Redline Proline 2 frame (has gusset behind seat, CS bridge, Redline Oval stamp)375996 1982 Redline Proline 2 (has the gusset behind seat, CS bridge, Redline Oval stamp)499612 Unknown Year, Redline MX-III frame502365 1984 Redline MX-III frame (has gusset behind seat, CS bridge, Redline Oval stamp)502867 Unknown Year, Redline Proline (CS bridge)505092 Unknown Year, Redline MX-III frame (has gusset behind seat, No CS bridge, Redline Oval stamp)507159 Unknown Year, Redline MX-III frame (has gusset behind seat, No CS bridge, Redline Oval stamp)510537 Unknown Year, Redline PL-24 (CS bridge)5 Digits08453 1978-79 Redline Proline.15188 Unknown Year Redline Microline Assorted Codes Giant Made Giant made should have two separate code areas, 1 on each dropout.