The A9 headset has some real negatives with the claimed positives. I was drawn to the claim of less rolling surface indentation (or fretting, take your pick). I used campy NR or good grade clones for a number of years, starting with my first nice bike in 1973 (Fuji Finest) and through my early frame building efforts. Every headset became notched after a season or two. My adjustment process was to start with a slightly loose setting (and the top lock nut snug enough to not have it or the threaded race move during...) and rock the bike fore and aft on a locked ft brake to feel the slop. Tighten the adjustment a tad and repeat the test until the slop JUST disappears. Check after initial ride. The shop that taught me much of my foundation was pretty focused on this 9along with other bearing adjustments on new bikes, something that's lost these days I sometimes think).


So in the 1980s I came to know of the roller bearing headsets by Stronglight, via the early Treks. When I started my retail shop (Bike One in Cleveland Heights, OH) in the later 1890s I ordered a couple. Initially I was impressed. Light weight, nearly same tall stack as Campy NR (so no change to steerer length, I could retrofit), replaceable rolling surfaces (the conical inserts), available in a 27.0 or 26.4 crown race, silver or black. A lot of pluses on the surface. My next few frames wore these units. As I was a budding shop owner my personal building was a couple every few years. In between I installed a dozen + for customers looking for more durability then mid cost balled units had.


But after a few years I found the conical inserts were also showing "denting"/fretting. So I started to step up my game. One thing I found was the lack of empty internal volume. Why this comment? Grease needs to store somewhere so it's oils can feed into the rolling elements over time. I used both the "O" ring sealed A9 and the standard unsealed versions and didn't see much difference in the grime that I found after a few months when I would take apart the headset to check, clean and regrease. Yes, I was regreasing my (and wife's) primary bikes a few times a year by this point. I would rotate the conical inserts top to bottom to extend the life with each rebuild initially. Soon I was just replacing the inserts with fresh once a year (or so).By now I was buying replacement bearing kits. My theory then was that the extra parts were shifting WRT each other and what seemed like a snug adjustment wasn't enough to prevent this shifting about between the inserts, the cups and the bearing retainers. (And yes, I was greasing ALL surfaces with every rebuild).


I had a while before also began to set the headset a bit tighter then I was taught in an attempt to lessen the insert wear. The greater friction of these cylindrical rollers (not conical) meant that a freely rotating steering could also be a loose headset bearing adjustment. Yet a sung one meant a tight steering feel, not what I was brought up with. Even with these changes I was still not happy with them. But you know how it is with "family" you tolerate and only move on when you can't stand things any longer. I still have a couple of old frames/bikes with A9s on them in my garage.


So what changed? I decided to forego cost and get the best, Chris King. While the same attention to head tube facing is needed the results were far better. Much narrower an adjustment range with a slop to no slop setting. Far more free a rotation. Better sealing (although some CK stuff isn't as good in this aspect). Less denting/fretting (as in none with the dozen or so units) I've (and wife) have used. because of the better sealing the grease volume is a lesser issue, although CK's still have a small open volume inside. My main issue is the tiny ball diameter. As we all know the load capacity is a square of the ball diameter, and linear with the ball count.


The last thing I'll denounce is the claim that the A9 and variants help with speed man's wobble (shimmy). I am riding proof that the mere addition of an A9 is not a solution for this. I have had a few bikes with shimmy, the club ones at speed, the touring ones at a much more sedate speed. I have ridden many hours with a wobbling front end. Shifted the load about, rode up and down, to either side, with locked or loose arms/hands. Done everything that I've read and then some to explore the give and take of shimmy on a few bikes. I've changes out headsets for a tour to not have any real change. So for the claim that a high friction headset like an A9 will fix shimmy I say not in my experience (and again this is over a number of years and a few bikes)


So this is why I don't feel that A9s, and their siblings, are any big deal any longer. I still have at least one NOS one on my shelf. Not sure if I'll ever install it. Andy.