Mine decided it wanted to be a drag chute today . About 6 miles into my ride home, I pulled over to shed a layer and that is when I discovered that my rear rack was now in a vertical state (with my heavy non-bike specific jacket strapped to it ). Both of the mounting screws that attaches the rack at the upper part of the seat tube were MIA. Luckily, I finished the ride without any further mishap.

The rack is now in "time out" in the garage, while my rear fender gets to see the light of day again.

Time for some thread locker

Man you must have been going fast

I had a rack that did that once. It was an old Eclipse rack that had two small screws that could be loosened to adjust the length of the rack. While on a tour with the rack stacked full of crap above my panniers, both screws came loose. One of my riding partners saw the mountain of stuff falling and bolted past me. At first I didn't know what had happened, only that I suddenly had a bit more drag. Mine acted more like an anchor than a drag chute. Thankfully, nothing was lost. I just tightened up the screws, repacked, had a good laugh and set off again.

Also, +1 to the thread lock compound. Since I started using it, I haven't had one shake loose in decades.

For me, yes. Fast as compared to some around here in general, no.

I don't know if those bolts worked themselves loose from the way I manhandle the bike during the loading/unloading from the SUV, or if some one (who surely has a very special place in Hades reserved) removed them.

hihi! I first thought you meant an administrator should lock the thread!! ...too much internet, too little nuts 'n bolts!

I have had rack screws come loose, they do it of their own accord. The solution is either thread lock or a better washer. Some kinds of star washer can lock up a bolt well enough.

Preventive maintenance...

I'm always amazed at how many bikes come into the shop with loose rack mounting bolts. I always check them when a bike is brought in. They are loose about 25% of the time.

I just got back from the store to pick up some more bolts and nylon threaded heads to lock my rack and fenders to my bike. Earlier today I had a surprise visit from the bottom of the fender on my leg. One bolt came out and the other one was just about to.

I have several of those locking washers, that look like they are split in the middle, but I would rather be safe than sorry.

I had that happen with an old Cannondale rack on my old Cannondale. My 1st 'tour', an S24O.

The front of the rack came unsecured and the rack, loaded with tent and panniers, rotated back until my Planet Bike SUperflash began to bear against the tire.

The tire chewed through the plastic on the light before I could get stopped, but a little duct tape kept her flashing for awhile.

Alas, she nonetheless grew despondent in her disfigurement and flung herself from her specially-crafted bracket and into rush-hour traffic on the ride home one cold, windy night. So it goes...

R.I.P, Blinkie