The new Boson has been billed by Isaac as ‘the ultimate competition level carbon road bike‘. The company has years of experience in carbon, it’s no surprise that Isaac has used a whole range of techniques in crafting the bike, and varying tube profiles, a tapered head tube, massive bottom bracket shell – with a Press-Fit BB86 bottom bracket – and internal cable routing all feature.
HIGHS: Stiff, high-performance frame
LOWS: Flexible stem, unexciting wheels
BUY IF… You’re looking for a competition bike and don’t mind changing a few components
The frame is designed to be stiff, that huge bottom bracket shell held in place by a deep, almost teardrop-shaped down tube and box-section chainstays. Both the chainstays and seatstays taper towards the dropouts.
The bike’s not particularly snappy, which is perhaps largely to do with the Mavic Aksium wheels. They’re solid performers, but they’re not going to set the world alight and usually feature on much less expensive machines. But take the wheels out of the equation, and the Boson is a stiff bike that transfers power well. Yes, there are more comfortable bikes out there, but the ride was never harsh enough to rattle our fillings.
The Boson sits in the mid-ground between a sportive machine and a race bike. We’d choose it if we were looking to improve our personal best for a century ride; it doesn’t have quite the comfort of a sportive-specific bike but even five or six hours in the saddle didn’t leave us feeling like we’d done 12 rounds with Muhammad Ali.
Throughout our rides, the Boson egged us on to push harder, but it balanced that urgency with entirely predictable handling, rapid changes of direction being carried out with the minimum of fuss.
Apart from underwhelming wheels, the build is, for the most part, spot on for the price. Shimano‘s 6700 series mechanical Ultegra offers the perfect balance of performance, weight and price, while the Boson’s frame is also ready to accept Di2, using a chainstay-mounted battery.
Our only component issue is with the Isaac aluminium stem, which we found a little too flexible. This is noticeable when you’re riding, as the bike lacks the side-to-side snap you find on stiffer bikes when out of the saddle.