The old rule was that they were suited for heavier tires only, because they chew up the sidewalls. Good for gumwalls but not skinwalls. That's why the BB dynamos became popular. They could be used on lightweight higher end bikes. BITD most people with racing bikes had to make do with a wonder light. I did. By the later part of the 80s and 90s, expensive battery systems were what most enthusiasts used if they needed lighting.