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The weight weenies in cycling are an interesting bunch. Some do it in a genuine pursuit of performance (or at least perceived performance), while others do it purely because they like the bragging rights. Either way, there’s clearly a huge market for parts that save weight, and mass is also one of the few measurable elements we have on which to base a purchase.
I’m still a bit of a weight weenie these days, but I was a die-hard in the past. I would weigh a batch of tyres to find the lightest one, mill material away from my derailleurs with a Dremel, and replace standard steel bolts with ones made of aluminium and titanium. Sometimes, I’d even just remove some bolts altogether (I don’t recommend it).
And many years ago, I bought myself the original Cane Creek AER headset when it was first released.
That headset boasted minimal cups that were aggressively machined, but the real weight savings came from a Norglide bushing that took the place of the standard upper cartridge bearing. That bushing was supposed to let your bars turn freely and without play as usual, but in reality, it was saddled with major compromises. It wouldn’t stay tight, it never rotated as smoothly as a conventional bearing, and in general, it just didn’t feel right. Things got better over time as the bushing wore in, but it was never as reliable as a standard headset.
And so out the headset went, replaced with the extra 40g of a regular setup.
So when Cane Creek announced the overhaul of its AER headset at last year’s Eurobike, I was intrigued. Gone was the bushing on this new AER-Series II, and in its place is a new cartridge bearing partly made out of aluminium. Cane Creek offers it as a complete headset (sold in separate upper and lower assemblies), but the bearing’s standard outer dimensions mean it can also be purchased by itself as an upgrade for existing headsets. An updated version of that Norglide bushing remains available aftermarket exclusively for road use, too.
According to Cane Creek, this layout reduces weight by 35% as compared to the company’s flagship 110-Series cartridge, but without impacting durability or performance (at least when used in the intended fashion). Unlike the original AER headset’s Norglide bushing, this new bearing is pitched for use for road, cyclocross, and even cross-country mountain bike use.
It’s (mostly) all about the bearing
Most modern road frames use fully integrated headsets with bearing cartridges that sit directly in the frame; there are no separate cups. And so for me, the key part of the new AER-Series II headset is the bearing.
Replacing a full-steel bearing with the new AER one saves 6-10g, depending on size; replacing both bumps the savings up to approximately 16g. But while you can buy just the AER bearings alone and whittle away a few secret grams that no one will ever know about, further savings can be had with the full AER-Series II headset. As compared to a standard Cane Creek 40-Series headset, the complete assembly could save as much as 46g.
As with the original AER, the AER-Series II is built with a hyper-machined upper cover; so much material is removed that the steerer tube is exposed when installed. The thin aluminium compression ring is captured within this upper cover, and there’s an o-ring hidden inside to keeping the elements creeping into the bearing. The bottom assembly is simpler, consisting of the AER bearing plus a lightweight aluminium crown race with an integrated low-friction seal.
If your frame uses a Zero Stack system (with separate cups that sit nearly flush with the head tube) or conventional external cups, then those cups are similarly machined for further weight savings.
The AER-Series II top assembly also includes a regular steel starnut, but with a lightweight aluminium preload bolt and machined top cap. The alloy bolt is one-third the weight of a regular steel bolt, and is anodised in gold – sure to let everyone know the bolt is light. The cap itself is a thinly machined aluminium item with relieved sections.
At 8.3g for the cap and M6 bolt, those two bits are certainly light and yet remain perfectly functional. However, those pieces are designed to work with a star nut (or other compatible compression device), and so they might be tossed aside if your bike has a carbon steerer using a more specific preload system.
For those looking to take the weight game a step further, Cane Creek also offers its EENut compression cap assembly, an item James Huang reviewed previously.
No doubt that item is light, but I personally didn’t have much luck with it. The larger internal diameter on aluminium steerer tubes fell outside the range of the EENut’s expanding wedge assembly, and I wasn’t comfortable with the sharp edges or the lack of material support it offered in a carbon tube. Given my experience with it, I’m thankful it’s sold separately from the headset.
Sold separately, there are also AER headset spacers available to match the hollowed top cap. Despite being made of aluminium, these spacers are marginally lighter than common carbon fibre versions at just 3.7g for a 10mm-tall size, and they also feature interlocking edges for a smooth fit with each other. They’re sold in 5 and 10mm heights, and cost US$13 and US$15 each, respectively. Yep, not a cheap spacer by any means, but they are machined in the US and impressively detailed.
How it performs
Once installed, there’s little to differentiate the AER-Series II headset from a stock steel-bearing headset. For sure, its aesthetic is different, and yes, your scales may flicker on a different number after the decimal point, but the way it performs is pretty much the same.
To be honest, I’m not really surprised by this finding, although it’s worth noting that despite feeling the same in everyday use, the AER bearing still has a (slightly) lower load rating than a full-steel bearing.
“Most headset bearings, including the 110, utilize 1/8” (3.175mm) ball bearings,” said Cane Creek engineering director Jim Morrison. “Generally, 41mm [cartridges] have somewhere around 20. To achieve the weight-savings with the AER bearings, the outer diameter of the bearing needed to be reduced so that aluminium could replace steel in that space. To do this, the AER bearings use 3/32” (2.381mm) balls. The trade-off is a reduced load-rating on the AER bearings in exchange for the weight-savings. Given the intended use (weight-conscious road or cross country mountain bike), the trade-off is more than worthwhile as only the most extreme DH or enduro racing begins to approach the load rating of a standard bearing.”
Load rating aside, one has to wonder whether long-term durability will differ with a smaller bearing; aluminium isn’t as hard as steel, after all, and I would expect the AER-Series II to be more prone to damage if run loose. bearings show absolutely no wear or tear on the outer surface to date, though, so Morrison’s claims seem to hold true.
So is there a downside? Well, there is the matter of compatibility: currently, AER headset bearings are only designed to fit with existing and popular Cane Creek headset sizes. If your frame happens to use one of these common sizes, then it’s no problem. However, an increasing number of high-end bikes use forks that have the lower bearing seats (crown races) molded directly into the structure, and many of these may present compatibility issues. For example, the AER lower assembly isn’t compatible with Cannondale’s CAAD12 or equally new SuperSix EVO.
Other than that, there’s the obvious price tag. For such a small component and one that offers a relatively small weight savings, it’s certainly a product best saved for those that own their own scales and aren’t afraid to trade money for a disproportional number of grams. If replacing a perfectly functional set of headset bearings and nothing else, then the cost per gram savings works out to be roughly US$3.50/g, and whether that sounds like a good deal or ridiculous waste will be up to you.
However, for those in the eternal pursuit of a lighter bike, this new AER-Series II headset, and in particular, the bearings, has proven to be a perfectly functional upgrade, and one that won’t scream to the world that you’re trying to cheat the climbs.
The Cane Creek AER-Series II headset is available in a variety of sizes to suit integrated (see Cane Creek’s website for details), Zero Stack, and external cup standards. Prices for complete top assemblies vary from US$60/AU$110 to US$70/AU$120; the bottom assemblies range from US$46/AU$88 to US$50/US$99. The AER bearings themselves sell for between US$21/AU$46 to US$32/AU$60 each, depending on the diameter and size required.
Sharing the same aluminium-encased concept to the CaneCreek AER II bearing, FSA also now offers an ‘SL’ headset bearing in a variety of sizes. We have not yet compared or tested this product.