So tt's are by far my worst discipline, when riding my road bike i usually ride like contador, in and out of the saddle and am certainly a climber sprinter. I am working on my tt skills and longer seated efforts my knees start to get this pressure and my quads near the knee kind of aches. i also get this when pushing power seated on my road bike but usually alleviated when i stand.

The only thing I can think of is that the nose of your saddle is too far down which can put a lot pressure on your quads, and also knees. The fact that when you stand you feel fine says to me the saddle angle may be the issue. I might try tipping the nose up very very slightly. Ride that for a bit and see if it helps, and then make further adjustments.

funny thing is that i just leveled the seat as it was pointed waaay down after a bogus bike fitter fit me about a year ago. could it be too low of a saddle? how perched on the nose should i be? should i be able to ride comfortably during say a 2.5 hr ride? or is it do the tt and get the *f##k* off type deal. I can raise my seat higher for a shorter effort buit longer rides the bike just blows

Sounds like a bike fit issue... Probably a combination of seat height and set back.

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"Suddenly the thought struck me; my floor is someone elses ceiling" - Nils Ferlin

ok thanks