The Rush is Cannondale's marathon bike. Standard models are aluminium, but for 2007 Cannondale have launched four bikes with carbon mainframes. We thrashed the top-end Carbon Team - it may look much like a standard Rush but it's a very different machine...
Cannondale started experimenting with carbon composites recently and now make some of the finest carbon frames around. The Rush Carbon's front triangle has a wonderful flowing design that is stiff and light, yet able to take a lot of abuse. The only part of the frame that's not carbon is the new 'Hot Box' CNC'd alloy swing arm. This is lighter and stiffer than previous models, offers more tyre clearance and provides a healthy 2.5:1 leverage ratio to the shock.
So does this result in a better ride than the already excellent alloy Rush? Yes - the carbon frame is much more compliant than its aluminium sibling, and in terms of handling it's laterally and torsionally stiffer. The back end is solidly connected to the main triangle, with none of that vague wandering feeling because the wheels track in unison, which is most noticeable over rocky terrain. The ride is tight and responsive, the bike doesn't get knocked around, and it rides sure-footedly on all types of terrain you'll encounter on a marathon.
The frame and key components are designed to work as a whole - a concept Cannondale call Si (System Integration). With the BB30 Si bottom bracket and the Si head tube and headset system, the frame should really be viewed as a chassis system.
The Rush Carbon Team sports the much improved Lefty Speed Carbon SL 110 fork and a Fox RP3 shock, both 110mm (4.3in) travel. The excellent Cannondale Hollowgram Si crankset has a higher stiffness to weight ratio than even the new Shimano XTR.
The seatpost is still a 27.2mm item - Cannondale have resisted the pull of simply fitting a large diameter seat tube to gain cheap and quick frame stiffness. Lightweight Mavic CrossMax SLR wheels keep the bike rolling and a mixture of Shimano XTR and SRAM X.0 shifters and mechs power the transmission. Finally, Avid Juicy Ultimate disc brakes provide lightweight but very capable stopping power.
The low overall weight of just 10.2kg (22.5lb) is a big bonus on the climbs and the single pivot rear suspension system gives minimal pedal feedback, even when climbing with no ProPedal or lockout. However, being able to lock the shock on long fireroad ascents is great because it allows you to run the shock softer so you can better enjoy its performance on the descents.