Originally Posted by
diabloridr
Here's a failure for everyone to chew on: Zoom aluminum post (no longer in biz,
AFAIK). Failure was at the point where the post enters the frame (a natural stress concentrator). Approximately a 3/4" long fatigue crack at the front of the post, the remainder of the post cross-section failed in brittle fracture (textbook failure for aluminum). Post is 13 years old, has about 25,000 miles on it. It would have received a cursory visual check sometime in the last year.
Wow, that one lasted a long time. Most Zoom failures I've seen or heard about happened with far fewer miles.
One of our friends had one fail on their Cappucino about 20 miles from the end of a century: all of a sudden she was holding the bars and her captain's saddle. They raised her stem to free up some of the remaining seatpost mast (he was really tall, so it had a lot of exposed mast) and finished the ride with his saddle about 5" too low... still pulling a line of wheel suckers.
Anyone with those Zoom seatposts would do well to keep an eye on them or, at this point... to replace them if the tandem they were installed on was ridden very much. It seems like it's more about when, not if.