What happens when you mix a state of the art, 110mm dual suspension platform, great parts, 27. 5 inch wheels, and some of the most advanced use of aluminum in a bike frame in the industry You get a do anything mountain bike that's light enough to race and inexpensive enough that you'll let yourself, called the 2015 GT Helion Expert Complete Bike. The frame of the Helion Comp you see here is made out of 6061 T6 aluminum alloy. Who cares, right You will. This is often regarded as the best all around alloy from which to make bike frames. It's mostly aluminum, but also has composite components of magnesium and silicone, blended in the proper proportion to bestow the metal with rigidity, deformation resistance, and incredible torsional strength while still being one of the lightest alloys on the market. In the Helion, the tubes are butted and hydroformed to exacting thicknesses all over the frame, allocating strength and stiffness where they're needed while eliminating weight where it's not. The bottom line is a frame that is ready to take your worst while helping you ride your best. Helping out here is GT's revolutionary Independent Drivetrain suspension platform. The idea of isolating the drivetrain so that it's not affected by suspension movement is nothing new, but GT's approach is, and it works really, really well. The crankset and the rest of the drivetrain make their home entirely on the rear triangle, unlike many designs that put the crank on the mainframe and the rest of the drivetrain parts on the rear triangle. The problem with this is suspension compression that occurs with pedal force, robbing you of efficiency. It's simpler to build bikes this way indeed, the I. D. system on the Helion is complicated to look at, but it works. Sprinting or out of saddle climbing is rewarded with hardtail like efficiency, not dependent on a shock's damping, yet it's incredibly compliant, and the front half of the bike remains extremely stable. One spin and you'll se...