On this morning's ride, which was a road ride done on my mountain bike (the transition from riding more or less always on the rollers to being able to ride outside sometimes gets clunky, especially when my road bike may or may not still be in the travel case since a couple of months ago), I kept thinking about "okay, you can roll along at a slightly slower speed on the mountain bike, but in the transitions is where your speed really gets hammered."
(not from this morning, though I did wear those shades)
This morning's loop was one I've done an infinite number of times, on every bike I own and with every kind of wheels and tires I use, in all weather conditions. If I was to look at data from each of them, there would be some fuzziness between rides done on road bikes versus cross bikes. A windy ride on a road bike could be look, according to tracked metrics, like a ride done on a cross bike with cross tires in better conditions. But then you could pull out a few segments and see "oh it was hammer windy from the west and that was that, okay." But a ride on the mountain bike, there's no overlap there. Always slower. Which is obvious, but it illustrates something about how we maybe ought to be thinking about speed.
Speed comes and goes in mysterious ways. You're nailing a segment, all time ludicrous speed, and the wrong gust of wind happens at the wrong time and it's all for naught. Or you're going through a demanding corner into a false flat that always feels like you're driving through mud, and the right gust of wind happens at the right time and you sail right up it. Really good mountain bikers are fitter than the average bear, but they're also better at speed maintenance through challenging segments. So they leave a segment with better speed than their less fit peers, and their better fitness allows them to gain more more speed at lower cost. Racing against truly good mountain bikers is humbling. Or, as happened this morning, you do that corner into a false flat section on a mountain bike, and you put the effort in that would keep you going sort of 19-ish on a road bike, but instead all of a sudden you're going 15. It craters fast.
In the olden days, before we'd gone to wind tunnels and such (which makes it the really olden days because 11 speed for Shimano road was still sorta new when we first went to the wind tunnel), Mike and I used to talk about our understanding of wheel aerodynamics in terms of the few pedal strokes you didn't need to take out of a corner, or the couple of pedal strokes you could skip at the end of closing a gap. In a lot of ways, I think we were more onto it then than we knew. Discussions about speed have morphed back into this, and people seriously question the validity of wind tunnel tests at all anymore.
Rolling resistance has obviously become a huge thing, and so has drivetrain efficiency and all of that stuff. The conversation around speed has changed a whole lot. You used to not be able to even talk about wheels without a wind tunnel test, and we were for sure in that camp. Now? Is anyone made more certain about the real world applicability of one choice versus the other thanks to a wind tunnel test? I think they show directionality, and there's apparently good correlation between predicted and achieved results in things like Bestbikesplit.com, but for the meat of you who are reading this? I don't know. You could do a Chung Test, but is all of that where people really want to go?
If you're Victor Campenaerts earlier this week, you don't care about transitions. you accelerate once, get as aero as possible, and then hold on for dear life. That's not how most of us ride. I read that Wiggins said before the attempt that if Campenaerts starts the attempt, he'll get the record. It's so predictable that you can know whether you'd make it or not before you even start - down to atmospheric pressure and all these things you've probably never thought of as many times as you've ridden a bike.
I think that technique, knowing when to go full gas to maintain some speed in order to get through a tough section quickly or enter a new section with a higher initial speed, is what turns a rider who can smash out the watts into a TT god or goddess. And that to a degree, now that equipment is sort of type-formed around intended purpose (TT with deep wheels that all sorta kinda look the same these days, for example), we're back where we were 10 or more years ago.
It seems that we've gone to tremendous lengths, as an industry, to be right back where we were in knowing about how to make good equipment choices for how we want to ride.