Drop Handlebar Selection
First, we need to get some terminology straight.
Drop Handlebar - the most common type of handlebar for road riding, touring, and randonneuring, typically allowing a more aerodynamic riding position than upright city-style bars. Lots of hand positions.
Brake Lever Clamp Diameter - The measurement outside to outside of the area that clamps to the stem.
26.0mm - standard road handlebars
25.4mm - standard city, upright, and MTB bars
31.8mm - "oversized" for modern drop bars and MTB bars
Grip Clamp Diameter - The measurement outside to outside of the bar to which your brake levers and shifters clamp.
Having a long ramp section means your hands can roam freely forwards and backwards, which is invaluable during a long ride or tour. This handlebar has a medium length drop for improved aerodynamics and handling through corners. Flare is a modest 30mm (15mm on each side).
Our Randonneur Handlebar has similar features to the Course, but it has a slight upward sweep by the stem clamp. This is a very traditional randonneur-style bar that can be seen on loads of French bikes of yesteryear. The sweep means a slightly more upright position in the hoods as well as the drops! Ramps are the same measurement as the Course handlebar. Flare measures 60mm. Remember, drop bars are measured from center to center of the drop. If you want 42cm (center-to-center) hood-to-hood, get the 48cm model (480mm - 60mm flare = 420mm).
The last offering in our drop bar selection is the Dajia Shallow Drop (Adrian's favorite, which she used on her C&O trip). The ramp section is shorter for a lower reach to the hoods and the drops are shallower so you don't need to lean over quite as much to find an aerodynamic position. The bar has 0 flare, which allows you snake through the peloton or around parked cars without worry of snagging. This bar is very popular for modern builds as well as for people wanting a shorter reach bar.