When you think of the seat tubes of a 49 and 61cm Tarmac, there's a size difference, sure, but you probably don't know that different materials were used to make them. And actually, this is true throughout the size range. For example, the ply that reaches from the bottom bracket to the top tube on a 61cm uses a thicker, stiffer carbon fiber than what’s used on, say, a 49 or 56cm frame. This ensures that both big and small riders will feel just the right amount of seat tube deflection, which'll save your back and posterior on long, hard days in the saddle.

You know that instantaneous acceleration you get from a Tarmac? One of the main contributors is bottom bracket stiffness. Everyone talks about it, but most don’t realize that bottom bracket stiffness values aren’t linear throughout sizes. Say what? Well, a 61cm needs more material to meet the same stiffness standards as, say, a 49cm. And for this reason, we added three-times the amount of extra-long pitch fibers to specific areas of the bottom bracket in order to reinforce the larger sizes. This is where that race-winning Tarmac "snap" comes from—no matter the size.

While bottom bracket stiffness may be the key to power transfer, head tube stiffness is paramount to the Tarmac’s perfectly precise handling. Railing corners, navigating through the peloton, dodging last-minute potholes—yeah, that’s all head tube stiffness, which is why we put such an emphasis on nailing it. Due to the nature of physics, larger bikes and their longer tubes need more stiffness to meet the same standards as their smaller counterparts. So, with the Tarmac, we determined that by adding plies in different orientations, and in precise locations, we could get the same “corners on rails” feeling throughout the entire size range.