On Monday, April 17, 2017 at 1:52:58 PM UTC-7, Doug Landau wrote:
The stem is two months shy of 15 years old, but I don't want to have
this happen again.
Get a new stem. This one is a flawed design. There is built-in problem with the shape of the part, and that is a lack of remaining metal around the bolt hole. The stem has been made bigger around the front bolt hole to overcome this, but it still has the 2-bolt-1-failure problem. The traditional shape does not make this concession to ease-of-handlebar-change, and carefully places the single bolt in the rear where there is plenty of metal surrounding the threads.
The traditional design is both less likely to experience a bolt failure, and - in the wild guess dept., be more likely to hold on to the bars and remain usable in the event that one does.
Deda Murex 2-bolt:
https://www.google.com/search?q=deda...f3AGoQ_AUIBygC
3ttt traditional:
https://www.google.com/search?q=3ttt...w=1306&bih=724
Doug - a stem should NOT be designed in such a manner that it is being held from failing by a bolt. These should be only there to put the parts together and the forces should be held in check by the design of the stem.
Yes, most stems are not so designed but most stems come from China where they don't have to worry about lawsuits from Americans.
A stem should have TWO bolts to tighten it to a steerer only to tighten it from rotating. And two bolts so that one breaking does not disable this capacity. Why on Earth would anyone question that? The handlebar mount likewise should have four bolts on it and the mount should be angled and a step placed in it so that the stem itself is carrying the load of a handlebar and not the bolts that are only there to assemble it.
Old fashioned threaded-head style stems were vastly overbuilt precisely because they were afraid of aluminum. We have more experience and better alloys today and don't have one single angle of stem to pretend racer with.
And those old stems had way oversized stem bolts and still failed because of bolts being given sidewise forces in most of them other than Cinelli who were real engineers.