Felt's F-Series carbon road racing bikes have undergone a major transformation for 2011, abandoning the prior generation's aging (relatively) small-diameter cross-sections and abrupt tube joints for a far more puffed-up and organic looking structure more in tune with other high-end competition.
According to Felt, the smoother lines and more gradual tube cross-section transitions came directly from FEM (Finite Element Method) analysis, which showed the bigger and more consistent forms were much better at distributing stress across the entire structure rather than concentrating the load in smaller regions.
Semi-rigid polyurethane rubber internal molds lend much more highly controlled – and thinner – tube wall and joint dimensions, too, as well as providing more compaction to produce a stronger end product with fewer weak spots. Other new features include a tapered 1-1/8 to 1-1/2in head tube, a BB30-compatible bottom bracket shell, cleverly convertible mechanical/electronic routing, and hollow carbon dropouts.
Felt's new F-series frames boast a much more 'puffed-up' appearance than the outgoing version along with a major boost in claimed stiffness. See any aluminum in that bottom bracket sleeve? That's because there isn't any
For the top-end F1 frame, stiffness has reportedly gone up a tremendous 45 percent relative to the older SL variant (and 15 percent relative to the old Sprint) while the bare frame is now claimed to be just 800g. We were able to bench-test old and new frames at Felt's headquarters in Irvine, California back at the launch and yes, it's a big and very noticeable – and much needed – improvement.
Our second-tier F2 frame uses a slightly less expensive carbon fiber blend and a 3k – rather than 1k – weave to help keep costs more reasonable but according to Felt, maintains the same stiffness numbers as the F1 with just a 50-60g weight penalty. While it's far from cheap at US$7,499, it's $5,000 less expensive than the F1 flagship, comes with the same fantastic Shimano Dura-Ace Di2 shifting bits, and is just half a kilo heavier with an actual weight of 6.78kg (14.95lb).
Componentry concessions include Shimano RS-80 clinchers instead of the F1's Mavic Cosmic Carbone tubulars, FSA's K-Force Light BB30 crankset, Ultegra brake calipers, a 105 cassette and a slightly heavier bar, stem and seatpost combo from Felt's in-house DEVOX brand. Or course, "concession" is a relative term here as few folks would complain about this level of build.
We're still waiting for the roads to clear after a recent wave of winter weather but stay tuned for some initial impressions soon, followed later by a more in-depth review.
Even at US$7,499, the Felt F2 is still one the cheaper Dura-Ace Di2-equipped bikes out there