Aero Gravel? Why not?
The Exploro is designed to fit road, cross and even mountain bike tires following the GravelPlus standard. The road and cross tires are 700c, the mountain bike tires use the 650b size, ensuring that all of these have virtually the same overall wheel diameter and therefore the same predictable handling.
Why is aerodynamics important on mixed-surface (asphalt, gravel, fire roads, single track) rides?
The key to the Exploro’s speed is the aero downtube that is wide enough to catch the airflow coming off the big front tire (a skinny downtube wouldn’t even touch the airflow). But at 50mm wide, we cannot use a full airfoil shape as the tube would be 150-200mm deep, causing too much surface drag. So we square off the tail, keeping most of the aero performance with a 50x75mm cross section that is also close to perfect for strength and stiffness; our Sqaero shape. The wide downtube also effectively shields the water bottles.
We didn’t want the Exploro to be fast in theory, but in the real world. So we tested at a realistic 20mph (32kmh) instead of the standard 30mph (48kmh). We also optimzied the frame for water bottles (tough to do long, epic rides without). We even designed the Sqaero shape to work well when covered in mud!
The Exploro uses Sqaero 50/25, with a 50mm wide downtube perfect to pick up the airflow coming off a wider cross or mtb front tire and lead it on to the water bottles. The seattube is 25mm wide to make it aerodynamically disappear in-between the bottles and the rear tire. The headtube, seatstays and custom seatpost also use Sqaero shapes.
The result? A muddy Exploro with 40mm knobby gravel tires and 2 water bottles (red line in the graph) is faster than the equivalent clean round tube bike is with 28mm slick road tires and without bottles (grey line).
Quick review is: this bike is amazing. Took it out for 45 miles of gravel and some pavement at Apopka in the 15-30 mph winds we had, yesterday. The handling is very much like a road bike, even with 700x36 tires. The biggest surprise was that I really expected a firmer, or even harsh, ride compared to my Open UP, but it turned out to be much more compliant in the rear. To be fair, I was on a Large Open and this is a Medium, so there is more post on the 3T Exploro, but it's an aero seatpost, so I thought that would be stiffer. I'll have to dig into how they engineered the rear triangle and post, to better understand it, but I'm not sure I care to understand. I'm just going to ride it, and enjoy.