This Cane Creek S6 headset's description says "without spacers". It goes on to say "does not include plastic headset snap spacers".

What the heck are they talking about and more importantly, do I need these spacers?

https://www.nashbar.com/profile.cfm?c...ess%20Headsets

The spacers are used to go on the steertube. Bicycle forks come in various lengths so spacers are used. You will need to use a few spacers. Look at your current fork and see how many spacers are on it. You can reuse them if you decide to overhaul your headset. It is very important to keep the proper amount of spacers on an all carbon steertube. Too many spacers can cause carbon steertubes to crack. As with all things carbon, the torque wrench is your friend.

I don't think it's the aluminum or carbon spacers that go just below the stem that they are talking about. At any rate, can't imagine those would be plastic anyway

Plastic (composite) snap spacers: https://www.universalcycles.com/shopp...&category=1693

You don't need spacers if you already have headset spacers. Any style will work. I'm not sure what the supposed advantage is of these spacers snapping together.

Cool. Seems like a good deal for the headset. Also good to know that they're talking about some kind of composite vs standard plastic for the spacers. Still, I'm glad they're not in the set; I'd never use them anyway.

If I remember correctly, Cane Creek makes a line of snap-together interlocking headset spacers that they sell separately (in fact, I think they call them "Interlok"). If this is what they are referring to, then they are not required, and any regular spacers will do. I guess the idea with the Interloks is that they align nicely when you're using more than one.

Here's a picture.

A composite is just plastic (usually nylon) with either a mineral, glass fiber, or carbon fiber filler (anywhere from a few % up to 60% based on my knowledge of what's available). These plastic can be very strong (approaching the strength of some metals depending on the loading) and relatively lightweight. Lots of cycling shoes are made with soles using these materials.

The headset spacers really take very little load assuming that the headset is adjusted properly.

Good point. They can get away with a looser tolerance on the ID of the spacer and still have the spacers look perfectly aligned as if their ID's were all a perfect fit on the steerer tube.

I ordered the S2 "without spacers" and they arrived with the interlok spacers. I prefer the aluminum myself.