If you are in the market for a new set of hoops the choices have literally expanded. From the inter-war years of fixed gear Six Day racers on the boards at Madison Square Garden to the dawn of the aerodynamic agein the 1908's rim profiles changed little in width or depth and it didin't matter if it was for a tubular/sew up or clincher wheels.
In the aero awakening of the 1908's deeper profile rims came to market. 50mm and deeper rims are now common on bikes in road racing and deeper includig discs at the back have been the norm for many years now. They were first manufactured in aluminum and soon were being done in aluminum with carbon carbon profile aero sections and all carbon. The benefits of these deeper profiles are a stronger rim and wheel, but the downside is a stiffer ride. Wheels with 25 to 35mm deep aluminum sidewalls are pretty much standard today, and a compromise design that provides a litl ebit of an aero advantage, are not too heavy, and are stronger without making the ride too harsh. Rim, spoke and hub material, as well as whel construction have ail improved dramaticall. Advances in metalurgy also contributed to lower spoke count higher tensioned spokes and drastically cut down on the amount of wheel truing that is necessary, while having almost no rider weight restrictions.
The newest change to wheels is a move to 23, 25 and 26mm wide rims (like the Enve pictured here at the top of this post). Benefits are said to include a more stable patform, better aerodynamics, lower rolling resistance, and more comfort. The reporting on increased stability is anectdotal. Folks who have commented on the wider rim and tires on RoadBikeReview.com seem to agree that they feel more confident when cornering on the wider rims. The cyclists on the site and the press tha have commented on the use of 25mm wide tires also say that the wider rim and tire combination allow lower pressure to be used (8 bar/116psi) contributing to the better ride. (See http://velonews.com/2012/05news/giro-tech-rise-of-the-25c-tire_218011).
Mavic which owned around 60% of aftermarket wheel sales (last I knew) has a helpful tire pressure chart recommending max pressure based on tire width. It recommends 9.5bar/138psi for 23mm wide tires and 9 bar/131psi for25mm wide tires. (www.mavic.us.sites/default/files/download/tirepressurrechart_eng.pdf) has also been reported that the 25mm tires have a lower rolling resistance. This seems counterintuitive, but the follks at Schwalbe say that at the same amount of air pressure 23 and 25mm tires have the same amount of rolling resistance. According to Schwalbe, a 23mm tire creates aless wide, but longer contact patchcompared to a 25mm tire at a lower pressure. This is so because the 25mm tire will make a rounder contact patch, or less long so the total contact area is smaller. (See www.schwalbetires.com/tech_info/rolling_resistance)
All of this sounds good, but I was curious abotu who had the idea for fatter rims. The idea, I feel safe saying, came form Hed wheels. Hed's C2 23mm wide rim debuted in 2006. The C2 was designed to create a more aerodynamic wheel and tire combination via a smoother transition between the 23mm tire and the 23mm rim. (See https://hedcycling.com/true_speed.asp) Although Hed started the trend and it helped differentiate their product when everyone else was still making 19-20mm wide rims, many of the competitors (Reynolds, Easton, Enve, and Shimano to name a few) have taken the concept and rolled with it. They all offer 25 and in the case of Enve 26mm wide rims. Interestingly, the two largest rim manufacturers, Mavic and Campagnolo have not embraced the wider rims yet.
Although the market for aero wheels is substantial, it is not the fattest part of the market. Cyclists commenting on the wider rim and tires on RoadBikeReview.com mostly say that they don't care if the wide combo is faster or not. They simply like the feel of more stability better.
For the best ride and handling characteristics a tubular tire is still the best option. The inflated tire is round and there are no sidewalls that have to work with a clincher section that can deform when cornering. A 23mm tubular on a 23mm rim would it seems provide the combinatino that Hed claims, but if you're afraid that the new generation of wider rims and tires will slow you down, don't be. The new wheels definitely seem worthy of a test ride if not your hard earned cash.
Owner, Reparto Corse