Drooling over Jan Heine's great book The Golden Age of Bicycles I noticed that some of these constructors used clamp on head-stems over threaded fork steerers.Did they strengthen the steerers or was there a high rate of failure at this point ? Clamping a steerer in this way over steerers that I have seen does not seem like a very good idea given the wall thickness left below the root of the thread. Geoff Duke Melbourne Australia