Looking at Lugs

Let's take a closer look at that most important frame piece- lugs. Sure, lugs exist primarily to hold the frame together, but long ago frame builders realized lugs could be beautiful as well as functional. They were a chance to show off one's craftsmanship and distinguish a bicycle. Of course, mass-produced frames aren't afforded the same detailing as a custom-built, but even production lugs can have style as well as strength.

A basic socket lug with no ornamentation on a cheaper frame. Plenty strong, but heavy.

Looking at the lugs used by Sekine over the years, we see several different types. Obviously, you'll find the plain-cut socket joints used on bottom-end frames; but there's variance through the years and more expensive models. Many of the lugs resemble, at a glance, the famous Nervex lugs from France.

The famous "Continental-cut" lug appeared on thousands of Sekine's mid-70s SHT, SHS, & SHL frames. The lug features fancier cutouts, and retains its strength while reducing weight and adding aesthetic appeal.

I have yet to confirm a definite timeline for the various lugs, or reason why a switch was made. Also worth noting is that several other Japanese frame manufacturers used the same lugs as Sekine. In particular, the Nishiki (and later Norco) bicycles are nearly identical, and similar lugs are found on the lesser-known Azuki brand. It's also worth noting that there are several different types of lugs on the mixte frames; these are most noticeable on the head tube-top tube joint.

Another basic lug, yet it has some ornamentation

Sekine probably had a few suppliers for their frame materials, (for example, Shimano dropouts) but most notably Tange Industries supplied many of the lugs, and much of the steel tubing used to build the frames. Tange also made the forks for most of the Sekine bicycles.

The lugs pictured above are on frames made perhaps a year apart, around 1980. The one on the left is a cheaper frame; the lug is chunky and heavy. The frame on the right has nicer lugs, with long smooth tangs and more defined curves. I'm not sure what Sekine used for brazing material, but I'll find out soon.