Hi chaingang. I agree with Greg adding that by '75 many guys were already riding / racing on 6sp. would have to look up when 12 T cogs came in, but in '75 type time the 6sp for the faster guys would have been 13x21 and 13x23. 13x26 was also prevalent, with the flatland fast boys and time trialers using corn cobs, and often a single front chainwheel. 14's were going out, but the standard bikes were as Greg described them.
> Date: Sat, 7 Jan 2006 10:29:31 -0700
> From: "Doug Van Cleve" <email@example.com>
> To: <firstname.lastname@example.org>
> Subject: [CR]Dumb gearing question
> Howdy folks.
> I realize that most serious riders have always tweaked their gearing to
> suit their taste and terrain, but I am wondering what typical 1975 road
> gearing would have been. For instance, 99% of new performance road
> bikes in say the past 10 years have come with 53/39 up front and something
> 12-23 in back. I gather most older bikes would have been 52/42 up front,
> what was a typical 5 speed freewheel? Thanks in advance :^)
> Doug Van Cleve
> Chandler, AZ
> Nothing wrong with that question....
> It was likely 13-21 or 14-22, if you're talking racer-boy (or girl) stuff.
> Sometimes 14-24 if it was a "stock" bike. 14-18 or 13-17 straight blocks
> if you liked pain or were more than a wannabe. :-)
> Come to think of it, on most complete ten-speed Production-type bikes of
> that era, you probably got a 14-28 or a 14-24 in most cases. The 14-24 was
> "racier" and far less common (maybe 9:1 ratio of usage?)
> Greg Parker
> Ann Arbor, Michigan