Originally Posted by
noglider
I remember reading about this a few years ago. It seems like a decent idea but the price is just a bit off-putting. I just looked at the
website. I see it's $125. If I'm reading the pictures right, it's a replacement headset where the top nut includes an extension that simulates an unthreaded steerer tube. So I wonder, is that extension attached to the original steerer tube by just the threads? That seems like a less reliable connection than a threadless stem adapter.
It's a bit of a combination threadless headset and quill adapter. Here's a pic of the "quill" part that goes into the steerer:
The threaded portion of the steerer that is above the bearing slides into a cylindrical void in the piece he is holding. It's an interesting system, but I fail to see any significant advantage over using a threaded headset and a quill adapter.
Just in case someone doesn't realize this, a threaded steerer MUST be reinforced internally, and this by design is done by the stem. The expander must engage below the threads. This distributes the lateral stresses over a large area and avoids concentrating stress at the thread, which would otherwise become an effective stress riser and almost certainly would eventually crack. That's why you don't want to clamp a threadless stem onto a threaded steerer, even though it will sometimes seem like a good fit. If the steerer does crack below the stem, there will be nothing keeping the handlebars with the bike except the cables, and you can't steer with those. This is a problem that Specialized experienced some years back and the results were not pretty. Steel threadless steerers have a thicker wall and are smooth, so stress risers don't become a problem unless there is notching. The safest installation puts the star nut or expander below the stem, as the failure will always be at the bottom edge of the stem.