This offering is for one new-old-stock Shimano HG90 (HyperGlide) chain in an alternating silver/black finish. These are older stock HyperGlide chains in that they were made in Japan, but they do incorporate the bushingless design (see discussion below for bushing vs. bushingless chain design/construction). We do not know their exact vintage (although a best guess would be the early 90's), but we have noted many newer stock Shimano chains are now being manufactured in factories outside of Japan. I don't know that this has any real impact in terms of quality, but we do have customers ask us about production locations (so we want to be clear in this regard).  I should also mention I do not believe Shimano has produced higher end HG90 series chains with the specs noted below in any factory (in Japan or elsewhere) for a number of years.

It's probably best characterized as a higher-end chain offering and should be compatible with most older HyperGlide road and mountain bike drivetrains (as it has standard derailleur chain dimensions...1/2" x 3/32" and 116 links). The outer width of the chain is also noteworthy, as it measures 7.4 mm at it's widest point and the cambered (widened) link plates is another "tell-tale" identifier of the HyperGlide design. These are fairly critical specs, because our shop catalogs indicate this width is compatible with Shimano 7/8 speed HyperGlide drivetrains.  A further review of Shimano shop catalogs indicates this chain was the factory match for the Shimano 600/Ultegra (road) drivetrain and the Shimano Deore XT (mtb) drivetrain from the early 90's.

It would also function OK on older 5/6 speed drivetrains, but we recommend wider chain options for those drivetrains (for reasons we discuss in great detail in our other chain offerings designed for such vintage drivetrains). This is not to say that one chain is inferior to the other, but there is a general rule that wider chains are usually made with heavier/thicker component pieces that will usually hold up better over the long term. As a result, when trying to maximize the miles logged on a particular chain, we usually recommend going with a wider chain whenever possible on vintage drivetrains. Having said this, please also keep in mind that having too wide of a chain on a particular drivetrain may result in poor shifting performance, so it's still advisable to follow drivetrain component specs when determining chain compatibility for a particular drivetrain.

In terms of condition, the few chains we have in stock (in this model) are all new and still retail boxed...although some of the boxes are quite shopworn.

A note about bushing vs. bushingless chain design/construction...
As we understand it, the bushing chain design represents the original construction technique by which all bicycle chains were assembled. This approach includes the use of bushings (i.e., something that looks like a hollow rivet) that hold inner plates together and allow link pins to pass through...connecting inner plates to outer plates...to ultimately construct the chain.  These bushings are not visible once the link pins are in place, as the outer plates cover the inner plates around the area where the bushings are located.  Although, a quick glance at chain ends (prior to chain installation), and specifically the visible inner link plates, should allow for a relatively easy chain identification.  More specifically, the bushing design with the hollow-like rivets will show themselves as thin rings connecting inner plates and covered by rollers.

In contrast (and as the name suggests), the bushingless chain design eliminates the bushing from the construction process.  This is how most newer chains are mass produced, as this appears to be today's preferred method of construction, especially for indexing drivetrains.  So instead of a bushing that holds inner plates together, the inner plates themselves have been re-designed to include an added cylinder shaped section that extends half the length of the inner chain width (or half the length of the old bushing).  It's these two cylinder shaped "halves" of the inner plates that meet in the middle to eliminate the need for bushings.  The link pins and rollers are still present under both chain designs, but the bushings are eliminated here, given the aforementioned advancements in inner plate design.  So to view the chain ends of a bushingless chain, and specifically inner plate ends prior to chain installation, you will not see a bushing-like ring...and this is the "tell-tale" for bushingless chain identification.

Now having said all of this, I've alluded to some preferences/benefits of the bushingless chain, but let me share a few other thoughts after discussing this topic further with some informed colleagues. As it relates to bushing constructed chains, there is the prevailing thought that these chains tend to exhibit more lateral stiffness, which means each shift will have to be precise, but this also means there will be less lateral "play" or "flex" in these chains.  The reason for the stiffness is the one-piece (but hollow) bushing that connects the inner plates.  On the other hand, the bushingless chain replaces the bushing with an advanced two-part inner plate design that exhibits a bit more lateral flexibility.  It's this lateral flex that appears to benefit the indexing drivetrains and one of the reasons why the bushingless chain has gained more popularity in recent years.  In the end, both chains probably have their own redeeming qualities and both designs will function on friction-based or indexing drivetrains, but there are still differences to be noted (and hopefully this discussion is helpful in shedding some light on these differences).