GreenPlease wrote:
Something that has me intrigued is how fast one could make something like the 3T Exploro with fast wheels (e.g. the CLX 50s) and fast tires (e.g. 25 CS or the new 25mm Hutchinson Fusion tires). I've fiddled with the geometry and I could hit my fit on an XL with a Sigma X stem and the MORF bars. Perhaps 5 watts slower than my Speed Concept with similar wheels and tires? 10w? What about with a bottle on the downtube? Perhaps a wash or a touch slower? It's so intriguing to me that I'm very tempted to pick one up and experiment.... just need to thin the herd a bit first.
First off, I can save you the money. I'll pay my way down to A2 if you pay for the tunnel time, because I have all these bikes. But the 3T Exploro is never going to come anywhere near 5 watts to your Speed Concept, aerodynamically speaking. That is just nuts. Not at any speed, at least not on the road. The bike (and the fork) of the Exploro is entirely (aerodynamically and in every other way) optimized to be fast with big tires, and to mate well with those bigger tires. The fork blades, the head tube, and the down tube are utterly massive. I have ridden this bike a lot, including in a pure road configuration with Enve 4.5 ARs and road tires that are an aero match for those ARs, and it's slow. Fast enough to hang with your buddies or in a good group ride, but out front, in the wind, you aren't going to come within striking distance -- I don't have data, really, but I have experience enough to feel strongly on this point.
The Exploro was built for a completely different terrain that cannot be easily tested for crr, per the poster above's point, but on the proper terrain it is absolutely faster due to the wider tire clearances and the ability to run those tires. I sometimes swear that when I'm running the Exploro with 47s and come off pavement onto some rougher gravel, the damn thing speeds up. You hit the rocks and you're like, WOOOO. The absorption of the lower pressure in the tires just takes all that turbulence and rolls right over it, not to mention the comfort involved with same. The 3T Strada, even with the 4.5s and tires (measuring) 30-31 down at 50ish PSI, feels like a ping pong ball over the same transition, bouncing around, hammering your arms, exhausting your wrists, and generally just plodding along. Note that this depends on "rougher gravel" as defined -- the smoother the gravel, well, there is an inflection point somewhere that the road bike is just going to be faster. Where that is I can't tell you, nor can anyone else.
If you were to tell me that the 3T Strada, if you could get steep enough on it and low enough on it to map to your current coordinates, could come within 10 watts of a Speed Concept aerodynamically speaking, on the road, I'd believe you for sure. But the Exploro, no way in hell. It's just not fast on the road/at speed relative to a pure aero bike. The tube shapes alone lend enough credence to this, as does 3T's own testing data on that bike.
GreenPlease wrote:
As an aside, after fiddling with a lot of different hydration setups, I don't think it can be overstated how practical a bottle is on the down tube. I wish more bikes were designed to accommodate a bottle along the lines of the Velocite Syn, Pinarello Bolide ($10,000 for a frame??!!), and now the 3T Strada. I'd love to see someone make a tri bike with lower triangle integration along the lines of what BMC did with the new Time Machine Road.
Pictures should say a thousand words with respect to everything in your comment above. At least they do to me. Because this is a subject dear to my heart and wallet, I've uploaded them to
an album. My conclusions, just from looking at this, and from experience riding these bikes, are that round down tube and seat tube bottles make no sense ever on an aero bike, aerodynamically speaking, including on the 3T Strada (unless you are obsessed with the Morf aerobars); aero road forks/head tubes/down tubes are designed to mate exceptionally well with the tire and rim, while gravel bikes are...not; and, you should ride the best bicycles ever made as they are made to be ridden, because they will be fastest that way, unless you have reason to believe otherwise. And don't put a round bottle in between your triangle on a TT bike. Practical is between the arms and behind your asshole.
As to the original subject and where this thread went, well, I just don't fucking believe anything Specialized says on these lame videos. I think they are either irresponsible liars or their wind tunnel is complete shit -- and I am, by the way, increasingly inclined to agree with trentnix that this tunnel is neither repeatable nor reliable. Funny how we won't accept budget builds when it comes to product, but we accept budget builds when it comes to wind tunnels that test those products. These are the guys who / the tunnel which told us we would save 52 to 90 seconds in a 40K by shaving our legs! This is just nonsense. Chris Yu went to Stanford, fine, he's smart, but it's a Samford tunnel and these are Sampson Community College level analyses.
I honestly do not believe that the depth or aero shape of your wheels matters as much as they say (aerodynamically), when you are running tires that measure 42 or 47, especially on terrain that requires such widths. I just don't believe that there is not an inflection point -- with respect to a rim that is designed with a 20mm internal/24 mm external width (SLX 24), which widths are a critically important variable that they failed to normalize against -- where the depth basically does not matter as you expand the width of the tire. The damn tire is double the width of the rim! Think about the laminar flow off of that tire -- it has to be huge.
Should you have an aero rim on your gravel bike? This is not a simple question. It's like the guy who posted asking what the best setup would be for gravel tri -- the answer to that hinges on what the hell gravel tri is, and what its course will be, and what its surface will be, and, and...
At Dirty Kanza, which is essentially a road race on dirt, yeah, of course the aerodynamics and depth of your wheels matters -- it does not matter as much as the conditions of that particular year of DK, or your choice of tires for those conditions, or how those tires mate with the wheels, or the pressure you run in those tires and how it impacts the rolling resistance across a 200 mile day, or how your drafting that impacts all of the foregoing (including aero). On gravel courses or on courses where 19+ MPH speeds for 8+ hours are not possible but where the course is best and most quickly navigated by a tire that spans 42+ on which you run pressure of less than 30 PSI, then my gut says that deep rim won't matter a lick.
The transition to gravel tri is going to drive everyone nuts because none of this is readily testable, and the variables are only going to become greater than those on a smooth road with (arguably) quantifiable environmental conditions.