Graduate engineer Dirk Zedler
Unfortunately, breaks in stems and handlebars are still frequent failures bike experts have to deal with. It has certainly been known for some time that problems can arise with these parts. When the first sportbikes were equipped with aluminium handlebars more than 20 years ago, many of them broke. The reason being: The curved handlebars were constructed like those made of steel, but were made of a light metal much more flexible, less solid and very sensitive to notches.
It was the same with mountainbikes in the mid-nineties. The handlebars became lighter and lighter, but no sufficient tests were conducted. The number of recalls does not nearly reflect the number of handlebar types in danger of breaking when in use. My advise: Exchange mountainbike-handlebars after two years at the latest or even earlier if you fell several times. When doing so, you should also exchange the stem if it notches the handlebar.
The tests of DIN, ISO and ISO plus standards are not sufficient with view of today’s riding style in mountainbiking. As long as manufacturers do not exactly describe the purpose of their products, very strict standards must be applied. Breaks on test devices are informatory, breaking bones only hurt.