Originally Posted by
MinnMan
OK, so this raises maybe a dumb question, but if they were facing a finish on a 20% grade where the speeds went down to something like 6 MPH (or so I read), why don't they put triples on their bikes that day?
Because a triple would be a hassle, which would require a new shifter, front derailleur, and possibly an entire new (Shimano) groupset, who doesn't sponsor most of the teams. Pros will be using lower gearing, however, by installing wider range cassettes, longer-caged rear derailleurs to accomodate those cassettes, and sometimes compact double cranksets.
Contador for example:
http://www.cyclingnews.com/features/...-red-at-vuelta