Originally Posted by
50PlusCycling
Steel is wonderful. The most comfortable bike I have ever ridden was a Trek 660 with a 531 frame. Not only was the frame comfortable, but the geometry was spot-on for me, and I have never been able to achieve the same pedal stroke on any other bike.
One of my steel bikes is a 84 Trek 660, I raced this bike for about 10 years. It was very comfortable and it also fit me like a glove. That frame was 531cs which stood for Club Sports. That special tubing was originally (my understanding) designed for the Trek 660 series at Treks request, but that tube set did find its way into a Holdsworth Triathlon frame, and into a few British Eagle touring bikes, which were light duty touring bikes. I bought my 660 as a frame and fork, the fork though was a bit different from the fully equipped factory 660, mine has Trek engraved on the top of each side of the fork, but there used to be a Reynolds sticker on the fork that said 531cs, so it's the same fork that the factory fully equipped 660 had just mine has the engraving. I built my Trek with 100% Suntour Superbe to try to copy the components on the 760.
I test rode the 760 and turned it down, because when I stood on the pedals to crank it up a grade, I found the rear wheel and stays would flex to hit the brake pads on both sides, and the chain ring would rub both sides of the front derailleur, when I test rode a 660 that did not happen, that was the reason I chose the 660 instead of the 760.