A customer dropped off the front wheel from a Racing Zero Competizione (high-end racing bike).
They're asking for preventive measures against new shaft catastrophic failure.
Just to be clear though,
the customer was the one who said "new shaft catastrophic failure,"
not asking specifically about "the aluminum shaft + hollow end bolts on both sides of the new small-diameter bearing front hub with two fewer bearing balls, where the right side keeps loosening first."
Looks like the term "new shaft catastrophic failure" has gained some traction in the community.
When I loosened both ends with a 5mm Allen key, sure enough, the right side loosened first this time too.
In the photo above, I'd tightened the hub shaft and right end bolt with strong threadlocker using a 14mm wrench and 5mm Allen key, but the 14mm grip surface barely shows any marks.
With the 14mm wrench on the right side and 5mm Allen key on the left... it wouldn't come loose for the longest time, and by the time the Allen key was flexing under all that torque, finally—with a "crack!"—it gave way.
Looking at the left end's threads, I could see they were pretty galled up.
If I coat those threads with grease and tighten them just enough so they won't loosen again in the future, then whenever I go to loosen it with 5mm Allen keys on both sides, the left side will always come loose first.
Aside from the structural defect (—I'm calling it what it is) of the new aluminum front hub shaft having a separate right end cap,
the problem is also made worse by how it's commonly assembled from the factory—
the left end gets torqued down like crazy (which was the case here too).
I checked the wheel for runout—there's a slight wobble and barely noticeable center offset, so the customer said they wish they'd brought the rear wheel too while they were at it.
They're asking for preventive measures against new shaft catastrophic failure.
Just to be clear though,
the customer was the one who said "new shaft catastrophic failure,"
not asking specifically about "the aluminum shaft + hollow end bolts on both sides of the new small-diameter bearing front hub with two fewer bearing balls, where the right side keeps loosening first."
Looks like the term "new shaft catastrophic failure" has gained some traction in the community.
When I loosened both ends with a 5mm Allen key, sure enough, the right side loosened first this time too.
In the photo above, I'd tightened the hub shaft and right end bolt with strong threadlocker using a 14mm wrench and 5mm Allen key, but the 14mm grip surface barely shows any marks.
With the 14mm wrench on the right side and 5mm Allen key on the left... it wouldn't come loose for the longest time, and by the time the Allen key was flexing under all that torque, finally—with a "crack!"—it gave way.
Looking at the left end's threads, I could see they were pretty galled up.
If I coat those threads with grease and tighten them just enough so they won't loosen again in the future, then whenever I go to loosen it with 5mm Allen keys on both sides, the left side will always come loose first.
Aside from the structural defect (—I'm calling it what it is) of the new aluminum front hub shaft having a separate right end cap,
the problem is also made worse by how it's commonly assembled from the factory—
the left end gets torqued down like crazy (which was the case here too).
I checked the wheel for runout—there's a slight wobble and barely noticeable center offset, so the customer said they wish they'd brought the rear wheel too while they were at it.