Are there generally accepted signs that your setup is either too stiff or not stiff enough? I've been thinking about this for the last couple weeks, and have been doing some research, but the "facts" aren't obvious to me. Lot of opinions, so maybe it's more of a subjective, rider-by-rider, feel thing.

I have a base tarmac, and sometimes it feels a little soft when I would like a little more responsiveness. I ride for fun and for exercise, so I'm not losing sleep over this, but I wonder if I could go to a stiffer frame or wheelset without any negative effects. I weigh 195 and wonder how much that would play into my perception of stiffness vs. somebody who weighs 150.

Any thoughts on this?

You won't find anything really objective on this. A stiffer frame may take away from comfort. Without flex you feel every road imperfection and bump. For some people they can't take getting beat up and their muscle and tissues might fatigue a little acting to absorb shock. Other people won't notice much of anything. Of course this isn't about the extremes.

Welcome to BF!

It's subjective. For me, the stiffer and edgier, the better. I bought a used set of Ksyrium SLs with aero spokes in the rear and carbon spokes in the front. They're 850g lighter than the stock set they replaced and way stiffer, and I love them. I've heard other riders complain about the harsh ride from the same wheels. I think a wheel upgrade, budget permitting, is good bang for the buck. If they're lighter than your current wheels, you'll notice a difference and you can always sell your current bike with the stock wheels and put the amazing wheels on your new bike.

Not disputing your assessment of the Ksyrium SLs but there are learned opinions that tire flex is so much greater than wheel flex that it is impossible to feel the difference between wheels. I, for one, am not sure what to believe. I will say that it is hard for a wheel that much lighter than another to be stiffer. Not impossible, but somewhat uncommon. A good portion of that weight on the old wheels was going into stiffness: heavier gauge spokes and/or more of them and thicker walled rims. The added weight in the old hubs wouldn't much affect stiffness but the rest of it would.

I think that it really depends on what someone means by "stiffer." If it's in reference to absorbing bumps, that's one thing, and I doubt there's much difference. If we're talking about lateral stiffness under load (hard accelerations/sprinting), then that's a different story altogether.

My personal experience is that this absolutely not true. I've effectively done a controlled experiment, same tires and pressures on different wheels. Not to answer this question, but to see if I did notice alleged ride and handling differences between 19mm and 23mm rims. I was surprised to find that 32H Velocity A-23s laced 3x were noticeably harsher than 20H/24H 30mm Kinlin XR-300s laced 2X. Exactly what is responsible for the difference, I do not know; could be the rim, spoke lacing, spoke gauge, spoke count. Probably some combination of all of the above.

I had to swap out front wheels last month while waiting for a replacement spoke and I could definitely tell the difference in stiffness between the two even with the same tire and same PSI.

Yes, the comfort factor is what I was actually referring to. I realized after the post that I did not separate that from the handling factor. I agree that would be more affected by stiffness aspects.

I guess I was referring to stiffer in the sense of performance under a higher load (accelerating, cornering, braking, etc). Makes sense to me that stiffer would absorb less road shock, although you would think in most circumstances that a decent tire with lower pressure would be the answer if one were to go on a longer ride where fatigue may come into play.