Timmi- 9 years is a long time to learn about geometry, glad you have. However I question your blanket statements, like:


"I have to wonder what method you used for rider positioning. No matter how tall or how short, unless a human has abnormally longer or shorter femurs or tibias, people fit onto a 72°-74° seat tube angle, in all rider heights. (and the choice within that range is more for intended purpose)."


Not all riders find that KOP is the best answer for their needs and most all fitting systems follow this principle. Some riders do have limb lengths that fall at the ends of the bell curve. In fact many riders seeking a custom frame have found that the common geometries don't work well enough, hence the custom choice. (I have a friend who while following KOP has no seat set back at all, her seat tube angle is 74+. She's about 5'1" tall and has about 1/2" leg length difference).


As to crit geometry- I always felt this was more about marketing then function. Sure bike companies (and the advertising dependent media) marketed bikes to the US crit scene at one time and used the term doing so. But merely labeling a geometry does not make the bike a better tool. Time and experience showed that. So was there a crit geo? Sort of, if you accept what those who want to sell you a bike say as the only truth. But this type of discussion isn't trapped in time. What we currwently call touring geometry was once professional racing geo. What was called crit geo is much like match sprint track geo but with gears and brakes.


"Aluminum and steel feel very different. Alu feels a little dead. Steel will flex and spring back, but most often, when it springs back, that energy doesn't move the bike forward because your pedals are past that point to benefit from the return movement. Aluminum isn't so springy - any flex it just absorbs and dissipates - hence the different feel."


Many who prescribe to "planning" would take issue with your claim that a steel frame's flex is not helping power the bike. Planers like to believe that the flex and the rider can have a sweet spot that makes the bike feel more efficient. Not sure I agree but their claims are interesting to think about. For an AL frame to absorb the flex and dissipate it would mean the frame will heat up (as it's gaining energy). It also would mean that the AL frame would not return to it's original shape as the flex was absorbed and not returned back into the bike. I don't see this outside of incidents which are also warranty voiding.


Larger tires result in slowing down a bike's snappiness is a well known method of taming a bike. The greater rotating weight, the greater tire flex collectively mute the willingness to change direction from steering inputs.


Bike handling isn't just angles and trail though. Your comment about having a better weight distribution is correct but I would say it goes to bike handling in general and not just the greater stability side of that bell curve. The hips do a lot of the steering and where that leverage point is (meaning the seat) relative to the tire contact points (front center and rear center are common references to this albeit indirect) influences handling a lot. Some feel that the hand placement WRT the front tire contact patch also is a big factor, I'm still undecided about strong a factor this is. And there are other handling/fit/geometry philosophies. What's interesting is that for all there's both someone who works really well and another who feels like crap.


Pretty much all the serious literature I've read on the subject of what affects frame stiffness suggests the down tube's torsional stiffness is a greater factor to BB sway then the seat tube's bending stiffness. Can you elaborate on your claim that the ST is the greater factor? Andy