Ishiwata Tubing

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Warming-Up
Dec 30, 2014
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#1
Good evening
I am from Christchurch, New Zealand.
I am looking for information regarding Ishiwata tubing pre 1980. I am restoring a 1981 Schwinn mountain bike that was built of Ishiwata pre 1979 MTB tubing as referred to in the 1979 Ishiwata 4130 Crome-moly tubing catalogue.
My questions are
  • The Ishiwata tubing is dated on the steerer tube 3.B. The frame is dated by Schwinn February 1981. My understanding is the tubing was made pre 1979 as it does not feature in the 1980 Ishiwata catalogue thus the date on the tube should be dated pre 1979 and Ishiwata would have dated the steerer tube when they sold it to be built as a bike. Tange tubing is dated similarly as the 3.B would indicate 1983 February on the Julian Calender. Thus an Ishiwata date of 3.B should refer to a date pre 1979 and the only way this could occur is if Ishiwata used the Japanese Imperial calender to which 3.B would refer to 1978. 3 would be an abbreviation of 53 years of the Imperial calender. I hope this is not difficult to understand but I cannot see an alternative.
  • The fork crown is very similar to a Faux biplane crown that Tange produced in early 1980`s. Does anybody have knowledge when Tange produced these crowns or did Ishiwata make their own as none are shown in the 1979 catalogue but a selection is shown in the 1980 catalogue, but they are very different.
  • Does any body have an idea as to whom could have built the frame as it is refuted to have been made in Japan and sold as a frame/fork only parts item up to 1983.
  • The Ishiwata tubing catalogue are on http://equusbicycle.com/bike/ishiwata/catalog70s/ and http://equusbicycle.com/bike/ishiwata/catalog2/index.html
I appreciate any information regarding this frame and Ishwata tubing
Kind Regards
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George5

Maximum Pace
Oct 16, 2014
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#2
The calendar thing doesn't make sense. Go with the western calendar. What's the diameter of the head tube? Any markings on the insides of the tubes? Interesting looking frame. Made by National I would guess and the lugs are most likely Tange. I'll ask my buddy's dad who worked at Schwinn back before they went belly up if he can remember anything.
 

TCC

Tokyo Cycling Club
Jun 30, 2013
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#3
Possible too, maybe, that the steerer, headtube and bb are Japanese tubing used to get the size accurate for those parts and the rest is something else. That is how Schwinn did their race bmx frames
 

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Warming-Up
Dec 30, 2014
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#4
Hi Thanks for the reply. The dating of the tubing does not make sense to me as the frame is stamped BS making it a Feb 1981 by the Schwinn system but located on the u/s of the BB. Comments have been made the location is not correct but I have seen one other frame that is identical for location. One of those variables that can occur. The steerer tube is dated 3.B. I do not know if Ishiwata used the western calender or the Japanese Imperial calender that is years ahead of the western calender. Tange used the western calender. The tubing is O/S, top tube 28.6mm, down tube 31.8mm, seat tube 31.6mm and head tube 32.6mm. The fork blades are 30.6 x20 x13mm. The steerer tube is 25.4 with an ID of 21.15 (BMX). I have not looked at the inside of the tubes, what can I expect to see. Do you have a reference to Tange lugs. The seat angle and seat angle is 70 degree. National is a company who had an involvement with Schwinn in the 1970`s. Asking your buddy`s Dad will help, the discussions I have seen is these frames where sold as a frame/fork only from 1980/81 and some failed with a head problem and replaced. In 1983 they appeared in the Scwhinn BMX catalogue as a part only with a similar frame that had BMX type forks. I think they came out of Schwinn involvement with BMX much as the Sting King but a totally different fish, not a Sting King. The frame has glue residue of a decal on the down tube that cold be a Schwinn with arrow.
 

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Warming-Up
Dec 30, 2014
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#5
George5
The Japanese Imperial calender or Japanese Showa calender runs during a Japanese Emperors reign starting from his birth and some Japanese manufacturers use it to date product. For example my Prince Skyline GTB is listed as a 40 year model but made in 1965. It was not until I applied the Japanese Imperial calender could I sort out variations in the model list. Not all Japanese manufacturers use it and it may not be used now. The western date for the year 1 on the Japanese Imperial calender is 1926. Manufacturers sometimes just use the last numeral as the one they list ie 3 could represent 1928, 1938, etc to 1978 which could mean the year the tubing was made, 6 years before 1983. This is also done when the western calender is used. I see a disparity from the bike manufacture of BS meaning 1981 and a date for the tubing used to make the frame of 1983. The 1979 catalogue lists the MTB tubes matching my frame and the 1980 catalogue does not list them. I see the tubes would have been made and dated in 1978, sold by Ishiwata at any time, even to the present date, but the 3.B stamping would not change or added at the time of sale.
I cannot see that tubing made in 1983 could be used to make a bike frame in 1981. I am looking for a reference to say what calender was used by Ishiwata. If they did use the western calender there may be another explanation for the Schwinn number.
In the Trek serial numbers, http://www.vintage-trek.com/component_dates.htm, this is mentioned in respect to early Sugino crank set numbering and also early SR cranks.
I do not know when Ishiwata started but I have been told they made the steel forks for the Japanese made Harley Davidson pre 1939.
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Warming-Up
Dec 30, 2014
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#7
Hi
Not a GTR but the type that competed in the first Japan GP 50 years ago and earned the R. I have spent 3 weeks in Japan in October to celebrate the 50 Anniversary of the race with the Prince Skyline GT clubs. A fantastic trip,lovely country and best of all, people. Will go back. Memories of travelling at 160kph with over 25, 50 year old GT`s, something else.
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