Should form follow function, or function follow form? In other words, do you first worry about how a design looks, or how it operates? While we certainly want our designs to look pretty, engineers are taught that form should always follow function, and that a product should be optimized for performance before all else. That is why we at Alto take the approach that we do, and our R-Symmetric hub geometry was based off of that notion.
So, what is R-Symmetric geometry? It stands for Right-Symmetric, and speaks to the idea that a more symmetrical wheel is a more balanced wheel -- this creates a stiffer, faster, and more comfortable ride.
The main feature of our R-Symmetric geometry is the drive side flange, measuring 109.7mm in diameter and incorporating heads-in spoke lacing. The purpose of this is to increase the bracing angle (the angle that the spoke makes relative to the center plane of the wheel) as much as possible, allowing for a more equal tension distribution between the drive and non-drive spokes. A larger bracing angle also creates a wider and more stable wheel, further aiding stiffness and ride quality.
So why don’t manufacturers push the non-drive flange way out there as far as possible to create a really large non-drive bracing angle? Well, some try, but it’s not quite as simple as that. The larger the difference between drive and non-drive bracing angles, the bigger the spoke tension differential will be between the two sides. So you could create a very wide stance and, in turn, have very low tension on the non-drive spokes. This creates a poorly balanced and flexible wheel. The true optimization of hub geometry was a tough nut to crack, but our R-Symmetric design increases the drive-side bracing angle so much that it allows us to have nearly the widest non-drive flange spacing with only a 35% drop in spoke tension (as opposed to an industry average of 50%). It is this balanced design that has created the Alto ride quality that we love so much!