• Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 4 other subscribers

Sekai Challenger 250

Anthony Viesti was kind enough to send this website some photos of his Sekai Challenger 250. Still needs to get fully assembled and I will post one shot of it all done. Looks all original.


June 1979 advertisement

So far this is the oldest known Sekai BMX advertisement. It shows the model “Superhawk” (#350). You can see the similarities to my own unknown 1977. But the ad says announcing Sekai BMX. Does this mean 1977 was the first year Sekai made a BMX bike? If so was my 77 made at the same place as this 79? If so who made the 79 for Sekai?

November 1979 advertisement

Since this ad is so late in 1979 Im not sure if it is advertising the 79 or 1980 models. So for now we will just call them 79/80 models lol.


Master List of Sekai BMX Models by year


Sekai Superhawk (350 – 4130)

Sekai Viper (380 – Mild Steel/Hi-Ten)

Sekai Skybird (450 – 4130)


Sekai Earthquake (4130)


Sekai Firefox (360 – TriMoly)

Unknown Year

Sekai Challenger 250

Great site on Sekai

Im still trying to ID my unknown 1977 frame. I found a 1979 ad in “Bicycle Motocross Action in a 1979 issue with a bike just like mine. Leading me to believe if Sekai was in business in 1977 it may be a Sekai. Then I found this great Sekai fan site: http://www.yellowjersey.org/sekai.html

Here is some quick info from it

We proudly sold Sekai bicycles from 1973 until their death around 1986.
Mr Katsu Yamashita worked tirelessly from his family’s firm,
Shinwa Trading Company, to ensure the very best quality and arrange all the myriad details of these wonderful bicycles.
Frames were built by Yamaguchi Frame in Osaka.
Professional Sekai frames, models 4000 and 5000, both road and track, were built by Miki
. Assembly was done at Sakai Export, Osaka.”

1983 Sekai Firefox

One of the BMX Museum members posted this scan of his old bike from a Sekai Brochure.  Courtesy of MnHiFlyr. With pictures below of him on his bike back in 1983! Thanks for sharing.

The  Sekai Firefox was a Tri-Moly race bike.

Sekai #360 “Firefox”
Champion 4130 Cro-Moly 3 Main tubes, 4.6lbs, Chrome Plated.
Tange #500W Cro-Moly Fork, Chrome Plated.
Takagi One-Piece Crank with a 5-pin Spider and Alloy Ring
UKAI “72” Alloy Rims.
Suzue BMX Hubs, Silver.
Kashimax Turbo Saddle.
25 lbs Total



1977 Sekai?

Ok hopefully someone who worked at Sekai or owned one back in the day can chime in. I got a unknown BMX bike about a year ago. Never saw another one till recently. The owner of that bike also doesnt know what his is. But both of our bikes are 1977’s. Mine had old old Kuwahara decals pre 1979 font when they introduced them to the USA. So at first I thought maybe a Japaneese 77 Kuwahara. But after making this site I saw the similarities to the 79 Sekai. Hrmm are these two bikes 1977 Sekai’s???

cleanedup250 bmxdads300

Sekai Team Roster history

In this one post I will attempt to list every factory and Co Factory rider the team has. Im not sure if they had a Co Factory or Factory Support or National team.

Factory Racers

Scott Campbell – (1982)

Christy Carlon – (1982)

Marty Ehnat – (1979-1982)

Roger Flagler – (1982)

Brad Fransisco – (1980-1982)

Scott Konaski – (1982)

Mark Mason – (1982)

Mike Mason – (1982)

Brad Moore – (1982)

Clarence Perry – (1979-1980?)

Aaron Walters – (1982)

March 1982 advertisement

The advertisement appeared in the March 1982 issue of “Bicycle Motocross Action”. The picture is a photo and not a scan. I dont own a scanner. The image is in better focus in the magazine. I dont know how to better use my digital camera to make sure the picture is in focus.


Marty Ehnat

Factory rider in 1979. Marty tripled at the 1979 ABA Washington State Championships.

Photo courtesy Bob Osborn. Do not use or reproduce any photos from BMX Action without his permission.

Marty Ehnat 1979

Marty Ehnat 1979