crumbling

The Ishiwata 4.C is what I am wanting to know. To me it indicates either 1984 and the month of April if the Tange dating system is used. That would put the frame manufacture well after 1984, probably 1985 to be made from this tubing. I am still going with the Ishiwata using the Japanese Imperial dating system as used by other Japanese bike part manufacturers. Tange uses the roman dating system eg 4.C for 1984 April. The Japanese system would date this as the 4th year of the decade, April. The 4th year of the decade decade would be equivalant to 1979 that fits within the manufacture year pre 1979. Refer to the Ishiwata catalogue as I noted back on Page 3 of the forum. Compare the sizing of the tubing on page 5 MTB tubing. The .833 does rfer to the diameter, BMX size. The steering stem nuts on my frame are Specialized. I also feel the fork crown is similar to 1983 faux biplane crown used on Trek 850 of 1983. From what tube sizing I have seen the Ishiwata and Tange are not the same size, maybe you may be able to compare these fork blades. I have read Trek did use Ishiwata tubing but I am not able to do a comparison to the 850. Check out the bike shop sticker to see if the bike shop is still open as they may have a very long memory,
Crumbling