33 mm works fine
Cycling journalist Ben Delaney has a really good video up on his youtube channel about gravel bikes that work well as road/endurance bikes and road bikes that can reasonably serve double-duty on gravel. Most of the discussion is around tire clearance and the head tube angle.
I found my sweet spot in the Van Nicholas Yukon Disc. It has a 72° head tube angle and I can easily fit 37 mm wide semi-knobbly 700×35c Schwalbe G-One RS tires, or my current favorite, the trusty old Schwalbe X-One 700×33c CX tires, which give me a bit more clearance and a lot more grip in muddy conditions.
As a side note: I enjoy the recent trend towards “all-road bikes” because many bike manufacturers can simply grab their old audax bike design from the basement, update the geometry slightly, and have something to present as new to consumers.
