Just browsing CL filling up my imaginary limitless, fully-funded, bike collection and I came across this oddity: Vintage Sekai professional road bike. The lug work is great, the carltonish seat stays look great, the overall paint job is great, the Superbe parts are great- however I can't seem to find anything about Sekai making a "professional" model. (Not to mention all the decals are completely off for a 1973 bicycle, the bad wrap job, and that black circle covering up something above the shifters, missing head badge etc.).

Did Sekai make a "professional" model? Is this a repaint of a nice frame with random decals thrown on it?

Here is a link to Sekai's on CR. Sekai bicycles

Evidently they did use the "Professional" label for a time on some of their upper end bikes. That is a pretty bike and reasonably priced with those parts and it's condition (if un-restored).

Interesting. So just some mismatched decals.

Not many decals available for Sekai other than the lower models. The "Professional" decals would most likely have been on the 4000 & 5000. Here are the decals Yellow Jersey has available; including the banner decals on the bike for sale. Sekai Bicycle Stickers from Yellow Jersey

A local shop had a Sekai track bike with no model name, and no evidence of ever having one, same kind of seat tube-only treatment...obviously a 4000 or better.

EDIT: Ok, found a picture I took and it's not quite the same...super cool bike regardless

That is indeed a Sekai 4000 as it was the only bike in the lineup with the model name "Professional", 5000 is typically "Superlight" it should be noted both the 4000 and 5000's were sold as F/F typically mail order. In 1973 though, there was another 4000 the "Criterium" which was a fully custom model as far as I know. Here's a link to a 1974 review of a Criterium. <-- Bicycling Magazine 02-1974 --> Sekai Custom Criterium 4000

Let me know if there's anything you'd like to know about the model and I'll see what I know.

Thanks everyone for the info. [MENTION=235305]RaleighSport[/MENTION] Is there any chance that the 73 was made of Tange steel? Everything I've found seems to point the earlier frames were made with Ishiwata and then they switched to Tange around 77?
Any way to tell the difference between the two without taking the bike apart?

The Tange #2 decal seems wrong. The 4000's were first made of Ishiwata and then Tange #1 . They switched to #2 sometime in the early 80's IIRC. Maybe a repaint?

IIRC the Tange switch is ~1975, and was Tange #1 for the 4000 model. Tange #2 IIRC again was implemented closer to the early 80's in the 4000 series, which another tell tale sign of would be a more relaxed touring geometry rather than road race. It's hard for me to tell from those pictures.

Assuming the paint is original, I'd date it as an early-mid 80's 4000 and also assume the tubing sticker is correct, I can confirm in 77 at least the seatstay wrapped over the TT like that, however they were still using chrome lugs at that point. As well as chrome socks on the stays and fork.
This is from the seatpost cluster on a '79 4000 (Courtesy of Don Gillies)


Very similar to the specimen we're looking at, but no cutouts.

This is a Miki built 4000 (Courtesy of Yellow Jersey)

Dated 1981 and almost matches EXACTLY to our specimen in question.
Note the seat stay bridge "lugs". the seatstay cluster,

There's just so many weird incongruities with the bike. Another is the 27" wheels for a top of the line bike. Even if it were a 73, I'd expect a set of 700c and I'd definitely expect them on a 80s model.

The Tange 2 switch seems to line up with what you're saying as Kactus' 1983 Sekai 4000 (https://www.bikeforums.net/classic-vi...ai-4000-a.html) is made with Tange 2 tubing.

So maybe this is closer to a 80s model than 73. But then where did that professional decal come from assuming the paint is original?

Here is my '83 Miki built 4000.

It is very similar to the '81 but has brazed-on cable guides on the top tube. The '81 and '83 also have fender eyelets unlike the one in the CL ad.

If we could see the serial number, we could determine the year from that.

Yup, but if I were hard pressed I'd speculated to date it at 79-81. Oh and the 27" wheel thing is pretty common with Sekai, so that at least matches with a lot of what the brand did.

Thanks everyone again - All good info to know. I emailed him to see if the seller will pass me the serial number. I'll update if he/she responds.