I rode El Tour de Tucson last weekend with Suntour DT shifters and a 2x6 drivetrain. So...yes?
Non-Scientific Observation: I was one of 1800ish that rode the full century and I noticed exactly
two similarly-equipped bikes. They're not a popular choice these days.
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A race bike in any era is a highly personal choice that at its "best" balances the requirements of fit, weight, handling, durability and cost tempered by the willingness to toss it and oneself down the pavement at considerable speed. ~Bandera