Oregoner

I want to determine what year my bike was manufactured. My hope is that someone here has a list of Sekai serial numbers or an eighties catalog or two that advertises this model number with the same components.

The original components still on the frame are all mid eighties from what I've been able to discover:

Sakae/Ringo Sp100AL pedals

Sakae/Ringo Custom P5 Laprade fluted seatpost

Sugino Gt Crankset

NITTO 115 bars

Technomic stem

Araya 27x1 aluminum rims

Suzue hubs

Suntour arx front and rear derailleurs

Suntour Symmetric downtube (suicide) shifters

DiaCompe AC500 brakes

As for the frame itself, the decal reads, "champion no.2 chrome molybdenum butted tubes tange industries ltd."
No proper head-badge, just a a decal. Same for all markings save a painted Tri-Comp on the forward end of the top tube and the serial number, which is as follows; M4B00317

dazevedo

Look thru this post should give you a year

https://www.bikeforums.net/classic-vi...-database.html

cdmurphy

Yours is almost certainly an '84. That serial follows the format for the "Miki" built Sekai bikes, as well as many of the top end Centurion frames. (I have a 76 Centurion Semi-Pro, which is essentially identical to the Sekai 4000 from the same period.)

Can you post some pictures of your frame? There doesn't seem to be much out there about the 3000 model. (Possibly a similar frame to the 4000, but without any chrome, or maybe down spec'ed components?

- Cameron

cdmurphy

Forgot to mention it could be either a '74 or an '84 based on the serial, but there doesn't seem to be any mention of a Sekai 3000 before the mid 80s. Also, I don't think there was a Tange Champion #2 back in 74, I think it was just "Champion" until the late 70s and they started to differentiate their tubing a bit.

The leading "M" is for Miki, then "4" is the year, then "B" is the fortnight, ie 2nd week of January, 1984. The number after that is a sequential serial number, but I'm not sure if it's per fortnight, or follows through the year. (T-Mar would be the one to ask, as he deciphered most of this for Centurion and Sekai bikes among others. Thanks T-Mar!)

- Cameron

T-Mar

It's definitely 1984. In 1974, Tange did not not use the number classification on their decals to differentiate between tubesets. The SunTour ARx derailleurs were 1982-1986 and the Sugino GT came out in the early 1980s, so everything points to 1984.

The serial indicates the 317th frame manufactured during the second fortnight (i.e. weeks 3-4) of 1984. There were two manufacturers who used this format but Miki of Japan was a known manufacturer for Sekai, so it is almost certainly a Miki product.

Oregoner

Wicked, thanks all. I'll comment again tonight/tomorrow with frame pics, so if there's anything specific you'd be interested in seeing in the center of the shot let me know.

Oregoner

Duke of Prunes

I'm glad to find this thread, because I just picked up a similar vintage (same year, same model, same fortnight) Sekai 3000 Pro Comp, S/N M4B00246, for $85 that, with an hour of Simple Green scrub, looks to be pretty pristine, though not the same assortment of components my peer Oregoner reports. Did Miki/Sekai/Norco sometimes dig related parts out of a bin if others weren't on hand, or were some frames assembled at local shops (I'm in Madison, WI, so likely Yellow Jersey here) that may have substituted? I'm sure the wheels are newer, but not sure why Shimano 600 rear derailleur and shifter, but Suntour front. And the seat post and downtube decals are fer **** --I'm inclined to heat them off, unless that is considered sacrilege, no matter how hideous the design is. At 54cm, it's too small for me, so I'll probably clean & re-grease and sell it on the relatively competitive spring Madison market.

Oh, hell...the forum doesn't allow me to put in links to photos because of my n00b status. Dang. I guess I won't show off the to-die-for '84 Trek 610 barn rescue I picked up for $45.

Bianchigirll 

I think most manufacturers reserve the right to change specs and use a similar item if something is not in stock. More likely, especially in the case of a rear derailleur it is a replacement part.

Welcome to the forums. Any pics?

Clang

Eh, you just need 10 posts to be able to post images. In the meantime, here's the pic from the ad. I saw this on CL.

Taylormic6015

T-Mar

It was definitely built in 1977 by Miki, It sounds like a Sekai 4000.

Taylormic6015