Cane Creek eeNut and eeCap headset preload plug review: ultralight, but at what cost?
Craig Edwards — the man behind eecycleworks — has a long history in the cycling world as a clever, weight-conscious component designer who lives on the cutting edge of performance and reliability. In the 1990s, he designed the Sweet Wings welded tubular chromoly crankset, redefining people’s expectations of what was possible with steel. More recently, his eebrakes dual-pivot rim brake calipers undercut Shimano Dura-Ace by half in terms of weight while still offering comparable power and lever feel.
Living on that edge involves occasionally falling on the wrong side of the precipice, however, and Edwards’ creations haven’t always been perfect. Those Sweet Wings cranks turned out to be prone to fatigue cracks long-term, for example, and while the eebrakes now have a good track record for durability, earlier versions were still subject to a recall. His wares don’t tend to be cheap to purchase, either.
But every product he’s touched always has something interesting to offer, especially for weight-conscious riders with a higher tolerance for risk.
Edwards has since handed off the production and marketing side of the business to the folks at Cane Creek — leaving him to concentrate on designing and tinkering — and his latest eeNut threadless headset compression plug still proudly displays his unyielding approach to shaving grams.
The eeNut vs. conventional compression plugs
The interior of carbon fiber steerer tubes are typically fitted with blocky aluminum wedge assemblies that not only provide an anchor for the bearing preload bolt, but help keep the stem clamp from crushing the tube. Although there are many different types of plugs out there, they’re almost all variations of the same theme, and with typical weights of around 40g, they’re fairly hefty by weight-weenie standards.
In comparison, the complete eeNut and eeCap assembly weighs just 10g. Granted, that 30g saving will hardly turn an average climber into Chris Froome, but its 75% reduction relative to a standard setup is nothing short of remarkable from an engineering standpoint.
Scaled up, it’d be akin to taking a standard 7kg road bike and whittling it down to less than 2kg.
Edwards has done this by trading in that bulky aluminum wedge design for a pair of thin aluminum cones whose bases expand outward against the inside of the steerer tube when the anchor bolt is tightened. On top of that is Edwards’ own ultralight headset cap and a custom machined aluminum preload bolt.
Installation of the eeNut portion is very straightforward, and not unlike a standard compression plug, but with far less material. From there, it’s just a matter of dropping the eeCap on top and then adjusting the headset with the preload bolt as usual.
Too little of a good thing?
Overall, the eeNut and eeCap seem to do their respective jobs just fine: the plug holds fast within the steerer tube, and the cap boasts a pleasantly low profile. There’s also a general sense of manufacturing quality with all of the components, and it has to be mentioned that the eeNut assembly is just flat-out cool. Even so, the eeNut gives me some pause long-term as it doesn’t seem to provide the same level of steerer tube reinforcement as a standard plug.
To get a more informed opinion on the subject, I consulted Raoul Luescher of Luescher Teknik in Melbourne, Australia. Luescher has applied a lengthy aerospace composites background to his own increasingly well-known repair shop and consultancy specializing in carbon fiber bicycle repair and inspection, concentrating primarily on frames and forks.
“People often make the mistake of thinking that the plug is solely to preload the headset bearings,” he said. “However, due to most carbon steerers not having much in the way of hoop strength, due to the difficulty in laying down 90-degree fibers in a production environment with the process used, the plug is important to contain the hoop loads from the stem clamp. Thus I do not recommend ultralight or poorly designed or installed plugs in most steerer tubes as we see lots of cases of delamination caused by the stem clamp.”
Luescher points out that most standard compression plugs provide so much reinforcement that they actually slightly increase the steerer tube diameter in the area in which they’re installed. When combined with the stem clamp on top, the effect is that the steerer tube is gently squeezed between two solid surfaces.
“A quick test that you can do to see the steerer change shape is to try and slide the upper bearing and split ring over the tightened plug region,” he explained. “Typically, they will bind as the steerer diameter is larger. When you loosen the plug, the bearing slides easily over that section, and tightening the stem has a similar effect in the other direction. The plug supports these compression loads and performs a structural role like a bulkhead. The lightweight ones typically do not offer this support.”
Indeed, the eeNut doesn’t force the steerer tube outward as with a conventional plug when the anchor bolt is tightened to the recommended torque — and lest you be tempted to simply tighten it a bit extra, keep in mind that the minimal contact between those expanding cones and the inside of the steerer tube concentrates loads over a much smaller surface area than usual. There was no damage visible inside forks I used to test the eeNut, but Luescher nevertheless offers caution.
“The point loading could trigger a delamination,” he said. “However, a delamination traveling down the steerer [from inadequate internal reinforcement against stem clamp damage] is probably the bigger concern.”
I also discussed my concerns with Cane Creek engineering director Jim Morrison. As expected, he was more optimistic about the widget’s efficacy and downplays the need for additional reinforcement in more modern carbon fiber forks.
“While it is true that there was a time when compression devices provided reinforcement to the steerer tube, the added strength was used to better resist the clamping force of the stem,” he said. “These days, compression devices serve only to preload the headset as fork manufacturers have shied away from razor’s edge designs that proved less than reliable in the real world.”
Nevertheless, Morrison admits that the eeNut’s sharp-cone design could cause some minor fiber damage within the steerer, but says any potential effects are “minimal.”
“Because the eeNut is relatively short, the steerer tube is gripped by the expanding cones within the clamp area of the stem. The stem, being fairly massive in comparison to the steerer, essentially eliminates any bending load on the steerer itself within this area. Additionally, the stress in a tube subject to a bending load is greatest at the tube’s outside diameter and decreases to zero as you move towards the center.
“Thus by gripping the steerer by its inside diameter, any damage to the innermost fibers has a very minimal impact on the bending strength of the tube. Finally, the knurling on the gripping edges of the eeNut is parallel to the steerer’s axis and thus is much more kind to the load carrying fibers that run in the same direction.
“To summarize, the eeNut gently grips the lowest stress area of the lowest stress area of the steerer tube. Of course, if your fork manufacturer requires the use of a specific compression device, you should heed that advice. But in the case of most manufacturers that give no recommendation for preload device, the eeNut will prove to be a safe and reliable component for the long haul.”
Living on the edge
Is the eeNut assembly intriguing? Absolutely, and it remains a marvel of clever aluminum design that, in my view, will undoubtedly appeal to riders who are hyper-focused on weight. But anyone who takes the plunge should do so with full knowledge of the caveats involved — and with a good torque wrench and ample friction paste in hand.
RRP: US$60 / AU$90 / £50 / €65