Top Tube Length When you draw enough frames (and one may be "enough') you'll see that the forwardmost point of a fixed-length top tube depends on the drop (barely) and the seat tube angle (heavily), and that alone---with nothing else added to the discussion---illustrates that a 57cm tt on one bike is not a-gonna put that point at the same spot as a 57cm top tube on another bike (with a different seat tube angle).
When you mix into the equation (as you gotta, there's no denying, there's no choice here, you just hafta) the additional and equally-if- not-more dramatic effects of raising the handlebar and dicking around (is that OK to say?) with stem length, then it is super easy to see that harping on "top tube length" without the context of all these other factors is like walking around the streets saying "I like spices." A long time ago, shortly after "Q-Factor" went public in Bicycle Guide magazine, there was another "factor" article, called "The Z- Factor" that talked more about the top tube, and addressed the thing Bob Cooper mentioned briefly here: "The top tube should really be measured from a point in space that is directly above the bottom bracket spindle to the center of the headset lock nut and level with the lock nut." May not be izzzactly the same, but "Z-Factor" iz cloze to dat. Anyway, EVERY tube on a bike frame matters, but a bike frame in the design stage is like one of those kid's toys made up of straight sticks and ball joints that you can reshape by pulling and pushing and squeezing to your heart's content, and every movment affects a bunch of other stuff. Please, when I die, don't engrave on my urn, "Dude didn't think top tube length mattered one whit." When there's a roar of public opinion that warrants a dissenting voice, and you're the mouse with that dissenting voice, you gotta squawk loudly to be heard above it, or else....nobody hears. So every now and then you can expect me to squawk about how top tube length "doesn't matter"....but I know it DOES MATTER, but it is like the spice in a sauce....izzall. That is what I think. Nothing's what I know. G -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
