Lou,
SEKAI bikes were, imho, boutique lighter versions of FUJI bicycles, Stopping at midrange models. In the mid 1970's SEKAI generally numbered their bikes in +500 increments according to the quality of the frameset, with three exceptions :
SEKAI 400 (just barely below a 500) SEKAI 2400 (just barely below a 2500) SEKAI 2700 (a SEKAI 2500 with a few parts improvements.)
SEKAI 500 : carbon plain guage steel SEKAI 1000 : likewise SEKAI 1500 : single butted steel SEKAI 2000 Special : single butted steel, better parts 25 lbs SEKAI 2500 Grandtour : double butted steel 24 lbs SEKAI 2700 GT Deluxe : double butted steel, better parts
They were all generally sport bikes with plenty of fender clearance. In the years when my friends and I were riding these bikes, from 1975-1980, the steel I think was Tange #2 or maybe Tange #3 (?).
The 1970's SEKAI bikes used : Sugino Maxy 110 bcd cranksets (except Mighty tour on 2700), and most used Suntour V or Vx derailleurs. The 2500/2700 used cyclone derailleurs. Dia compe centerpulls were standard on all models except 2500 (500g sidepulls) and 2700 (gran compe.)
The SEKAI line of bikes went up to mid-quality and stopped. SEKAI never imho made a bike with fat ugly lugs. There was never a "SEKAI 3000" model. Above mid-quality, SEKAI sold framesets (road and track) only.
The 4000 was a handmade higher-volume frameset-only, 0.8/0.5/0.8, with road and track versions, perhaps comparable to a Raleigh Competition, hand made in "Osaka by Miki". The 5000 was a very delicate superlight road racing frameset weighing 4.13 lbs, with two 0.6/0.3/0.6 frame tubes.
http://www.ece.ubc.ca/
Most SEKAI models had very little chrome (sometimes half chrome on the front fork), and had soft paint that chipped easily. The decals were delicate clear mylar that would scrape off easily. The badge in the 1970's was a silver decal with blue swirls above and below the name "SEKAI". The seat tube generally said "SEKAI" in large white outlined letters with olmpic-type bands above and below, and the downtube generally said "SEKAI" in similarly large white outlined letters. Before 1980, the model number and name were included, e.g. "2500 Grandtour", "2000 Special", "1500 Deluxe?", in black, e.g. :
SEKAI 2500 Grandtour
With the "2500 Grandtour" in black in much smaller writing. In this era the Tange frame tubing decal was yellow with blue outlines and it didn't say anything about chromoly, just butted or double butted steel.
I would compare my SEKAI 2500 very favorably to a raleigh gransport or Fuji America. These three bikes weighed about the 25 lbs, but the SEKAI cost $50 less than the Raleigh, had forged dropouts, gold drive train, 1" lightweight tires, suntour cyclone derailleurs and a light plastic saddle.
SEKAI offered a line of manufacturer labeled parts --
SEKAI Deluxe tires, 27 x 1 1/8, 300gm SEKAI Deluxe tires, 27 x 1, 270 gm SEKAI Deluxe Saddle, ?Fujita? ?Kashimax?, ~ 350gm SEKAI Frisbees (I have one) that came with the bike.
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If anyone is interested in restoring a SEKAI from the 1970's, check the URL above for most of the JPEGs necessary to make the decals. If there is enough interest I might try to produce some of the unobtainium decals (such as the Tange seat tube decal, or the head badge.) Andrew Muri at yellow jersey has seat-tube and down tube decals available from the early 1980's.
- Don Gillies
San Diego, CA