Welcome to the new and improved Proflex / K2 Tech Forum!
The guy I bought it from said they ran these VERY stiff as in almost as rigid as they could get....He did give me a "regular" ti spring, too.Also this frame was custom built for Beat Wabel who rode for Pro~Flex, then Cannondale..it isn't just a WayBig.... Um, I measured the top tube...middle of seatpost to middle of crown (straight line and have a whopping 24 inches). so I guess it's a Way, WayBig? [smiley=laughing.gif]
I remember Giant did a study on their riding team when the NRS came out. (Perhaps not a perfect comparison since that design has no negative travel, but a full susser, nonetheless). If I recall correctly, their tests showed that while the overall times were very similar, the effort (based on heart rate) was about 10% less with the suspension bikes. So even though the riders universally agreed that they THOUGHT they were going much slower, they were actually going just as fast and working less. Sounds like my kind of thing... I think we're all used to the feeling of full suspension by now. (Plus, just prior to that era, URT designs were all the rage - and those DID suck a lot of energy. Now that we have shocks that eliminate pedal bob though, URT may make a come-back).