Acros, the company which brought hydraulic shifting to the market, has a half dozen neat products tucked away on their website. The Acros Clamp, is their take on a integrated headset (or headset upper), designed specifically for carbon steerers.  Essentially, the product is an adjustable spacer which eliminates the need for a starnut or expander wedge. It utilizes a ramping system, adjusted via a setscrew, to put pressure against the stem and preload the bearings. They are hand built in Germany and are come standard with stainless steel ACB bearings but ceramic bearings are also available (at a premium).

Video and more specs after the break..

Weight for the complete headset is 70 grams and will set you back aprx $105 for the stainless bearings, and aprx $200 for the ceramics. To pricey for this conversation piece? The upper alone, at 54 grams, retails for $65. Both are available in either red or black.



  1. Will someone please clue me in to the benefits of a ceramic bearing headset? Slightly lighter? I can understand BB, pulleys and hubs, but I’ve never really thought my headset wasn’t fast enough.

  2. Seeing as the compression plug also prevents the carbon steerer from getting crumpled in by the constriction forces of the stem I don’t see how pushing up on the stem (as the Acros Clamp does) really helps make a complete system.

  3. I saw another headset not long ago that was adjustable in a similar fashion. I hate most of the compression cap assemblies out there, so this seems like a great alternative for carbon steerers.

  4. Easton did this years ago for their carbon steerer forks.
    For getting the stem low on the bike, they’re terrible (though not an issue for all fits).

    Easton’s was a saw-tooth profiled expander, that wasn’t the headset, but a spacer that was meant to be used on top of the top cap of the headset.

  5. Seems like that gap would be just big enough to let in all kinds of grime and gunk. Seemed like the conventional cap kept alot of that off of the top bearing.

  6. canyon does something like this right now too
    but they finish it with that grommet looking think on top that looks much nicer than the exposed edge of the steer tube.

  7. another solution in search of a problem. as mentioned, you still need an insert to prevent the stem from crushing the steerer and your min stack height is increased.

    Even worse, the upper ring is supported only at the two ramps, so you are introducing flex into the system because the upper ring can rock back and forth on the other axis.

  8. Anyone claiming that it is SOOO easy to crush a carbon steerer tube should actually try to do this 😀 it’s hard even if you use a vice at workshop, not to mention a stem! Been there, done that – believe me, it’s REALLY hard to crush a carbon tube.

    When it comes to the solution described here, it’s just great. I use a similar device (it’s called “Ring-go-Star” and is made by USE) and it’s completely solved my problems with steerer tube expanders slipping away from the tube. What is more, I believe this is even safer than an expander because it does actually cancel out any play in the headset which is extremely difficult in some forks which seem to be too slippery on the inside, which greatly aids steering. And for those who really feel the need to use some sort of an expander, Ring-go-Star does come with an aluminum insert for the steerer tube. And by the way, it’s much lighter than this Acros thingy as it weighs just 25 g for the spacer.

  9. Having used this system on a Canyon bike, I’d be weary. The Canyon version sucked, the stem (alloy) always sliped up the carbon steerer-tube resulting in a loose headset that you’d have to continuously re-adjust (unless you gorilla wrenched down the stem clamp, which is a great idea for carbon steerers). I’m not sure how to address this problem without modifying the stem. It was a unfortunate feature on an otherwise stellar bike.

  10. @dave- The upper ring is supported by three ramps.

    I think this looks pretty clever. Funny the Germans who designed this didn’t consult anonymous people posting on the internet.

  11. Actually, I have been using easton’s EA90SLX for 4 years. it has the threaded steerer tube core and a threaded insert to hold your headset’s top cap. works great. no slipping, no lateral forces, great system

  12. As long as it keeps debris out, it would at least have the advantage of keeping people from meat-fisting the torque on the top cap bolt. Some uninformed people think that it (and every other bolt in existence for that matter) has to be uber tight.

  13. @h2ofuel

    This is one more problem, I agree. On the other hand, many forks come with crappy steerer tubes which are extremely slippery (so that even sandpaper or CF installation paste do not help) and make people apply more torque to the stem and/or top cap (which in the latter case causes the expander to slip out instead of pushing the top cap against the stem/spacers). It’s just hard to believe that manufacturers can’t come up with a solution to this problem – a thin layer of a less slippery material would completely solve this problem.

What do you think?