Originally Posted by
Jughed
Personally - tested and verified using months of data on the exact same course... pancake flat bike, using a power meter. I have well over 500 rides on this path as data points.
I gained about 1-1.2 MPH when switching from chunky armadillo tires to GP5000's (about .75mph), then the rest with 40mm deep CF wheel upgrade. On a more modern bike to begin with, but not a full on aero bike - but semi aero. Set PB's at the same power levels over and over.
But...
I then bought a 2001 Lemond -bone stock except GP5000's- and blew all of those numbers out of the water. Then saw some marginal gains when I put 50mm deep wheels on it.
Why? Body position. The front end is stretched out a wee bit more and about 1.5" lower.
If I swapped out to a full new aero frame and kept the same body position/50mm wheels - I would only expect marginal gains, very marginal. Especially at the speeds/watts I ride at.
Equipment choice is a big one, as far as aero gains go...and often some low hanging fruit IMO. I think of the latest Giant Propel launch, where they claim(insert grain of salt here) that the new Propel 18ish watts faster than the old one IIRC. Sounds like a lot, until you read that most of those gains come from faster tires and a narrower cockpit. Even if it's an integrated cockpit, those are still more affordable changes than a brand new aero bike, and they're changes that will make a noticable difference.
Originally Posted by
Koyote
These points may not relate much to the pros, but for mere mortals, yeah: nutrition, recovery, position, clothing -- these are all much less expensive ways of getting speed, even if they are less sexy than a new bike. I was riding in a race last weekend, and for a time was behind a guy who had unzipped his jacket and was letting it flap wildly in the wind. If he'd just zipped it up, or removed it and put it in his pocket, he could've ridden away from me pretty easily.
Regarding the comment about your speeds/wattage: bear in mind that aero gains are cumulative with time -- in other words, if you are riding more slowly, those aero gains may be even more significant if you are riding the same distance.
The position argument makes me think of some of the recreational riders I see on long reach/short stack race bikes, yet they don't have the flexibility to maintain that position. Even if they do get into that position, their power production drops off at that tight of a hip angle. Many people likely just assume a lower cockpit is going to be more aerodynamic, but it's likely slower when they can only manage to ride around on the bar tops with locked-out elbows.
As far as cheap/easy marginal gains, add leg-shaving to the list. Even by the most conservative estimates, it's saving me 5 watts...I'll never turn down a free 5 watts.