After encountering this peculiar form of bicycle malady a few times over the past couple of weeks, I feel compelled to devote some thought to the rather particular phenomenon known as Cone Suck. Cone Suck, defined as the condition wherein the drive-side cone on the rear hub gets “sucked” into the center of the hub body as a result of continued riding on loose bearings, usually arises from a bent axle that causes the cones to loosen. Once loose, the cone nut on the rear hub’s drive side can become wedged against the bearing cage or the balls themselves and—because it has a right-hand thread—screw itself further into the hub body over time. While it bears mentioning that Cone Suck is usually the product of prolonged negligence, it can result in severe damage to the bearing cup in the hub body, including the complete separation of the cup surface from the rest of the hub.
The tell-tale signs of Cone Suck are not numerous, though the condition is not inherently difficult to diagnose. Considerable looseness in the rear hub axle, especially underneath the freehub body or freewheel (Cone Suck is generally associated with thread-on freewheels and steel hub bodies), is probably the most prominent sign that continuing to ride will worsen the situation. Pushing one’s drive-side cone into one’s rear hub takes equal parts patience and mechanical apathy, but its pecuniary consequences are certainly not insignificant and typically entail wheel replacement.
Excellent article; great investigative work. We’ve seen so many imploding rear wheel hubs in the last couple years that this really helps to better understand the problem. Would be nice if the manufacturers & engineers who spec and design these hubs would read this and modify them to help reduce this problem.