RiddleOfSteel

I am chuckling at the "blah blah blah" part of my quoting/reply. Well played.

I don't know if I'd call the 510 flexy when out of the saddle, but there is a lack of preference to do my said requested activity. I wouldn't say it feels dead at all, but it is no Columbus-tubed bike. My chestnut brown 510, when built with many of the parts that are on my 720, was amazingly efficient feeling in the saddle and one summer day (the day I actually did my longest ride ever at 70 miles) I absolutely flew for the first 40 miles. The bike was a really big part of that, and I don't think I would have been any faster on the 720. Who knows though... I'd say that a 510, at 25.5" certainly, has a character and a set of *riding preferences--as far as Venn diagram overlapping circles go, and thus far in my 510 journey--do not overlap as much as I want to.

A 710 and a 720 will definitely be two different bikes. A 710 and an '82 720 will overlap a lot more as they are both caliper brake bikes that offer similar (but different!) wheelbases and geometries. I'd say consider the 620 for loaded touring as well. A beefier frame with that Trek + DB 531 feel would take a touring load really well. 720, as reviewed years ago, does have more flex when loaded, and that makes sense. A 720 is a superb bicycle on its own, unloaded, which is why I ride it as such and will never put panniers on it. It's too good to weigh it down!

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* Ok, some in the weeds "blah blah blah" (lol) talk here regarding getting the 510 & Me Venn diagram: In the man-and-machine relationship, and certainly with my physiology, biomechanics, and sensitivities, plus preferences; in my experience, certain bikes are more accepting of a wide range of component setups, certainly with regard to "cockpit" setups. Bar width, headset-to-brake-hood reach, brake hood height in relation to the ground (in addition to coordinating its height or elevation from the saddle's elevation), stem length vs bar reach in total subsystem flexibility, brake lever type (are one's hands on the hoods like with brifters or to the outsides like with '80s and earlier levers). This matters in the saddle for sure, but I think it's a much bigger deal ***if one cares to find out because "something isn't quiiiite right"*** for out of saddle symbiosis between bike and rider.

How this relates to myself and the 510 is that wider bars (that generally provide more leverage) will allow me/a rider, at this size of frame, to yank the bike around in an manner that is out of sync with the rest of the frame. The front end goes first, and quickly (and easily), but the back end is a step behind and must catch up. Long crank arms for a given rider and/or frame can also do this. Too much leverage too easily (and thus quickly) applied and it doesn't feel right. Ghost peppers on salmon--there's too large a gap between input (peppers) and the subject (salmon) for it to be a complementary relationship. Fast bike parts on an old Schwinn cruiser, same thing.

Thus the possible combinations of solutions are a long quill stem (on the bike right now), with narrower-than-42 or 44cm bars as a longer reach slows out of saddle efforts and adds flex, while narrower bars decrease leverage and thus speed for rocking a bike side to side. I do know that heavier wheels and 23-25mm tires are not an ideal combination. Swap to 30-32mm tires on those same wheels and it's a lot better. Unfortunately, the lack of springiness/slower response becomes evident. The goal, in my mind, is to match components to the character of the bike so that in anything I do, it feels cohesive. And hopefully I can do that and get the bike's character to pair well with what I like to do. Some bikes are stiff, so let's turn everything up and jam out some hard miles. A 510 is on the other side of that spectrum. The interactions are more sinuous, not digital or high volume like a carbon race bike. Thus I will tailor the component set to pair well with the frame.