On 5/26/2019 3:23 PM, Jeff Liebermann wrote:

snip

More on Rivnuts:
http://www.pardo.net/bike/pic/fail-001/FAIL-178.html
Frame failed at water bottle boss. This is an aluminum frame
with a crimp-in "Riv-Nut"-style threaded boss. The frame is drilled
and the boss installed; the hole slightly weakens the frame and
the crimping creates some local stresses. A typical alternative
is to weld in a boss. In some cases, the weakening and stress-riser
effects of welding and of the boss section may weaken the frame
more than drilling a hole and using a Riv-Nut.

No one disputes that Rivnuts weaken a frame, it's just a question of how
much. It's unclear if that example involved factory install Rivnuts or
Rivnuts installed afterward. The latter is much more prone to failure of
course, though in most cases you can get away with it, depending on the
frame material and how well the drilling and installation was done.

The fact that people get away with drilling and installing Rivnuts does
not mean that it's a great idea to do it. People do really stupid stuff
all the time and get away with it, but that's not proof of anything. As
Jobst stated, "I don't know many riders who believe that drilling a hole
in a frame tube is a reasonable concept."

The other issue is that it voids your lifetime frame warranty. As we've
seen just in this group, people do occasionally take advantage of that
lifetime frame warranty.