Tri bikes are just as comfortable (or uncomfortable) as road time trial bikes, but have shorter top tubes and larger seat tube angles because triathelets are usually runners first and have massive quads but the rest of their cycling muscles are underdeveloped. A slack seat tube (like a road bike) lessens the load on the quads and forces the glutes to do more work.
Don't be fooled. A tri bike has aerodynamics as its main focus, not comfort commuter type comfort.
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Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --
the tiniest sprinter