We have to admit that it took us a bit to distinguish the differences between the R3 and Fi'zi:k's newest creation, the R5 Uomo Shoes. Some points are obvious, like the replacement of kangaroo leather for Microtex on the uppers and a carbon reinforced nylon outsole instead of the R3's carbon fiber. However, we're more apt to call those differences enhancements to both comfort and value. Now, the shoes feature more ventilation and a rather comparable level of stiffness at a fraction of the cost. And with only a 20 gram difference between the two, it calls into question, how much do we actually love leather and carbon So, besides 100, the question begs to be asked, what are the differences between the R3 and R5 Well, it all comes down to materials. Starting at the closure system, Fi'zi:k replaced the Sailcloth fabric found on the hook and loop straps R3 with its go to material, Microtex. Essentially, this is the same synthetic leather that's found on everything from Fi'zi:k bar tape to the uppers of the R5. In addition to these straps, the R5 features the same micrometric aluminum ratcheting buckle. This system allows you to fully tune the fit and volume of the shoes both pre ride and on the fly. The bottom two straps control the snugness of the fit at the metatarsal and instep areas, and are best adjusted before you hit the road and left alone thereafter. The ratcheting strap is what dictates the entry and exit adjustments. The loading lever is made from aluminum that's been mated to a stainless steel base. It has a double click adjustment capability with a full release mechanism at the base of the lever. Together, the three strap system eliminates any internal foot slippage that depreciates your efficiency. To evenly distribute pressure across the top of the foot, Fi'zi:k made the strap dimensions wide. The strap design allows you to easily lengthen or shorten the strap in order to precisely dial in the volume of the shoe. Under the closure, you'll find a we...