German-based carbon specialist Isaac (as in Sir Isaac Newton) has redesigned its top-end Sonic frame with a new true monocoque frame and light weight as its main objective. Indeed, actual frame weight on our relatively large 57cm tester is an impressive 990g (we had to build this one from the ground up) and the accompanying monocoque carbon fork is 380g with an uncut 1 1/8″-to-1 1/4″ tapered steerer tube.
The giant tube proportions suggest that the Sonic will still be quite rigid, though. The cylindrical down tube is nearly as wide as the bottom bracket shell throughout its length and the top tube begins as a massive unit up front before tapering down and flowing gracefully into the wide seat stays. The chain stays are also decidedly enormous at the bottom bracket. All of this surface area combined with so little weight does come with the expected price, though; a quick ‘squeeze test’ tells us without a doubt that the tube walls are frighteningly thin.
Be that as it may, we’re still looking forward to giving this one a go. Build kit is primarily Campagnolo including the Record groupset and Neutron Ultra clincher wheelset. Finishing bits include a Deda Elementi Newton oversized bar and stem, Selle Italia SLR Trans Am saddle and Veloflex open tubular tires. Total weight without pedals is a just barely UCI-legal 6.83kg (15.05lb).