Tear drop shape in stem?
 

I bought a new Jamis Aurora. The stem has what I can best describe as a tear drop shape cut into the inner edge of the stem where it slides on to the steering post. The post has a corresponding shaped rail that runs the length of the stem. This rail fits into the indent on the stem.

I have not seen this type of stem before. Is it new or is it unique to Jamis? The name stamped on the stem is Jamis.



I have a second stem I use to mount my handlebar bag. I am hoping to somehow cut an indent into the second stem. I use it on my road bike and hybrid.

The diameter appears to be the same diameter as the Jamis (I just eye balled it and did not put a micrometer on it. Assuming this design is not unique to Jamis, should the 2 stems indeed be the same diameter?

It's an ATS stem (adjustable threadless system). The idea is to make adjusting the stem height along the steerer tube as easy as loosening the stem bolt and sliding the stem up or down what is essentially a giant spacer with the "rail" on it, and then tightening it back up. The headset adjustment stays put during these adjustments. It's not my favorite setup, and the stem can be replaced with a conventional one if you want. It does serve the purpose of making it a little quicker and easier to adjust handlebar height without messing with a spacer stack. I just think it's one of those solutions looking for a problem sort of things.

Not sure if other bike brands equip new bikes with those or not, but I'm pretty sure they can be purchased as an aftermarket item.

I wouldn't cut up the second stem to fit it to the ATS, as this potentially weakens it to be dangerous should you wish to use it as a normal handlebar bearing stem in the future.

It's not the same diameter anyway, since it's a sleeve over the fork steerer. You could just cut it, and butt it up against the bag stem (presumably below the bar stem).

Yeah just figured that out. The stem is already cut up anyway so it will never be used again as a regular stem.


I am not sure I an following you about cutting it. I assume cut the ring in half? Then what would hold on the 2nd stem?

I 'm thinking of just picking up another ATS stem. Hopefully I can get my hands on a cheap one somewhere.

I have the same ATS stem on my Novara but I never adjust it so I might be willing to let it go. PM me if you're interested and I'll check on its dimensions.

you talking about this ? NVO COMPONENTS.

Yes that is the one. I need to find a cheap one as it is just being used as a second stem for my Ortlieb handlebar bag. Klickfix has a stem mount system that might work. The Klckfix fix is supposed to work with the Ortlieb but I am just not seeing how it works. I have a thread posted about it in the touring forum.

I have hung an Ortlieb bag on a klick fix bar bag mount myself the thing is you hang the bag as if a Klick fix bag ..

If you disassemble what you have, you'll see a length of sleeve with a rib on it that goes from the top headset bearing's wedge ring to just above the top of the steerer where the preload cap does its job, independent of your oddball stem clamped to the sleeve.

Now, with just the bare steerer poking out of the bearing, put your bag-holding stem on like normal because it's a normal stem, and then put the sleeve on. The sleeve is now the normal stem's stack height too long, see? Cut that much off the sleeve, put it back on along with the oddball stem holding your bars above the normal stem holding your bag, and the top cap will bear down on the headset via the sleeve and normal stem. Clamp the stems after setting bearing preload, viola.