My two cents worth: Well, it same then as now, really. More wheel dish was a factor back then too. The increased dish from 120mm to 126 circa 1975-6 compromised rear wheel strength and stronger rims were needed to compensate. Also, in the tough milieu of European bike racing, making it to the finish line, albeit on heavier rims, without buckling a lighter rim and then needing a wheel-change along the way began to be seen as an acceptable risk despite being able to sprint faster on the lighter rims. Also, using fewer spokes was seen as an speed improvement due to aero-dynamics. In addition, the quality of spokes got better with the arrival of DT brand, so reliable wheels could be built with fewer spokes at higher tension per spoke. So, a lot of things converged at the point in cycling history and lighter rims didn't always mean faster, as had been thought in earlier years.
Bill Bryant Santa Cruz, CA
Richard Rose wrote:
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>
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> e-richie wrote (in part),
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> >the heft of these rims were, in the day, a real departure
> from sub 300gm rims. the trend of lighter and lighter rims
> and a constant spoke count was being supplanted by heavier
> rims with fewer spokes.
>
> Why did this trend start - away from lighter rims? Doesn't this
> contradict the idea / goal of lower rotational weight? I know that
> today we are dealing with increased dish & all that - but why then?
> Richard Rose (Toledo, Ohio)