Steve Maasland writes: The ex-Roberto Conti De Rosa has the 172.5 cranks, and he is 189 cm tall or about 6ft2"
The interesting note here is that Armstrong uses 175s, he's not that tall, both the Coppi and Merckx bikes have 175s and you can see these beautiful rides on the Vintage Velos website. They may have been tall for their time, but they're not that tall.
I'm only 6'4" with a 36" inseam, and I've been using 180s since I was a kid.
Maybe what we don't know, really won't hurt us?
Can we start raging about something else now, like stem length and how important that is to goat herders in Nepal?