Headset hijinks: D-11 versus EC37/EC37

[hampco]

Since we’ve used both of these headset sizes here at HampCo Heavy Industries I thought a few words might be in order and some thoughts from others appreciated. Any errors are mine. So:

A “standard” inch-and-an-eighth (1.125” or 1 1/8”) or EC34/EC34 (“EC” means “external cup”) headset usually has a head tube with an outside dimension (OD) of 36 to 37mm. The inside dimension (ID) is 33.95mm and the minimum ream depth is 10.7mm. These work with so-called 1” (using an adaptor) or 1.125” steerers.

A new-but-really-old standard is the EC37/EC37 headset, also called 1.25”. We use these with a head tube that has an on OD of about 40mm as the ID needs to be 36.95mm with a ream depth of 11.4mm. This is a good choice where a) you have a large-ish down tube (38mm, say) meeting up with your head tube. It also allows use of a fork with a 1.125”-to-1.25” tapered steerer - like many modern gravel forks. So it’s a good alternative to using a tapered head tube or a 44mm head tube, which can look a little oversized on some builds. The White Industries headset will also work with an integrated 45º lower race, as on the No. 6 Road fork, as the lower bearing is deep enough to do so.

Head tubes for this size can be made in one's own shop or purchased from Paragon; White Industries and Woodman both offer headsets in this size. Reamers are available from Paragon or Ceeway.

The Pegoretti D-11 size, developed with Chris King, usually has a head tube with an OD of about 41mm. The ID is 38mm and the ream depth is 15.5mm. This size was developed to work with the larger 38mm down tubes and pair well visually with Pegoretti’s own Falz forks. I think the added ream depth here makes sense when you look at the head tube extensions that Pegoretti is known for.

The drawbacks to D-11, as I see it, are that it is not compatible with 1.25” steerers; the added ream depth turned it into a real bear when reaming titanium head tubes (not an issue for Pegoretti); and almost no one has the reamers. (I have one reamer here, I sold one a couple of years ago, and I know of no others in the US). As a little-known footnote, just before Serotta went belly-up they had a few D-11 lower cups and races made by King that allowed use of a tapered 1.25” steerer - they called it S-12, I think. We built one frame with that bearing, paired with an Enve AR fork, and it turned out great.

There’s a lengthy discussion over at Custom Frame Forum if you’re into that sort of thing:
https://forum.customframeforum.com/t...dtubes/1091/63

Y’all's thoughts?

[darkmother]

Informative post-thanks for that.