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2015 GT Grade Carbon

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GT, dominant in the world of mountain biking, first entered the world of road racing in the mid 1990s with sponsorship of the Lotto squad and the 1996 U.S. Olympic team. The company’s last forte into the world of road racing was its sponsorship of the Jelly Belly team at the end of the last decade. Since then, GT has slowly moved away from pure race machines. The company’s focus towards performance road bikes has culminated in the 2015 Grade Carbon. A machine that embraces disc brakes, wide tires and a renewed spirit of adventure.

The Grade Carbon frame is created using variable high modulus construction. Using different modulus carbons, GT is able to better tune the ride of the frame. Each tube is designed to provide lateral stiffness while increasing vertical compliance. The head tube is tapered from 1.25-inch at the lower headset bearing to 1.125-inch at the top bearing. The down tube is vertically ovalized with a rounded angular profile to stiffen both the front triangle and bottom bracket. The only tube in the front triangle that is not oversized is the seat tube – housing a small diameter 27.2mm seat post. The seat tube is bi-directional tapered at the bottom bracket for increased stiffness. The Grade Carbon frame weighs 965 grams in a 56cm and has clearance for 35c tires.

The Grade Carbon was designed using a two-section approach to maximize stiffness and vertical compliance. Power transfer is the priority for the down tube, bottom bracket and chain stays, so that section is constructed as the main frame. The top tube, seat tube and seat stays are constructed to provide increased vertical compliance. The down tube is oversized, descending into a PF30 press fit bottom bracket. The chain stays are equally robust, angling up from the bottom bracket to above and in front of the rear dropouts. On the non-drive side, GT takes advantage of the oversized chain stays by direct mounting the disc brake caliper.

The upper section of the frame is designed to leave the seat tube isolated, with the pencil thin seat stays forming a tight rear triangle and meeting the seat tube low on the frame before bridging to the top tube via GT’s distinctive triple triangle junction. This results in 10 mm of deflection at the saddle. The chain stays use GT’s Dual Fiber Dynamic (DFD) technology and use a solid glass fiber core wrapped in carbon. The glass fibers allow the seat stays to flex more than carbon, while the carbon wrap adds torsional stiffness and increased durability. For a balanced feel GT completes the Grade Carbon with its own tapered carbon fork that features offset dropouts and an oversized 15mm thru axle. The fork hits the scale at 470 grams.

The frame uses GT’s All Day Geometry, which features a taller head, tube, lower bottom bracket and longer wheel base. Our 56 featured a 56.5 top tube mated to a 71.5-degree head tube for increased stability in rough conditions. The 73-degree seat tube puts the rider in a familiar position over the pedals. As with most machines not dedicated solely to racing, the Grade Carbon Ultegra features a taller head tube and longer chain stays. The head tube measures 182mm, while the chain stays extend out 430mm.

First Ride
The Grade Carbon Ultegra we rode is noticeably smooth, but it was the bike’s responsiveness that garnered our attention. The Grade Carbon Ultegra forgoes the soft feel of many performance bikes with power put to the pedals efficiently delivered to the rear wheel. The Grade Carbon Ultegra cruises down the road with the feel of a steel-touring machine, combined with the weight and speed of a carbon race bike. The frame is light and stiff, yet lively with enough vertical compliance to make a noticeable difference on broken asphalt or long gravel sections.

The Grade Carbon Ultegra we rode was equipped with Shimano Ultegra Di2 11-speed components paired with Shimano hydraulic disc brakes. The Ultegra Di2 will not be available in the United States, and will be replaced with mechanical Ultegra. The Grade Carbon Ultegra rolls on new Stans NoTubes Grail disc road rims laced to DT Swiss 240 hubs. The wheels are wrapped in Continental Ultra 28c tires. The cockpit is comprised of a GT Drop Tune 14-dgree-flair handlebar, GT alloy stem, FSA K-Force Light seat post and fi’zi:k Aliante saddle.

Tackling a series of paved and gravel climbs, the Grade Carbon Ultegra can keep a quick pace, although the oversized tires add noticeable resistance when pushing hard. The lively feel of the bottom bracket combined with the stiff and stable front triangle make the Grade Carbon Ultegra feel efficient.  The Grade Carbon Ultegra climbs best in the saddle, taking advantage of its vertical compliance and maintaining rear wheel traction. Out of the saddle efforts are met with a responsive feel and smooth acceleration. On long gravel sections the Grade Carbon Ultegra settles in and one can keep the speed high.

Descending on the Grade Carbon Ultegra is very stable. The slightly longer wheelbase, slacker head tube angle and vertical compliance allow the rider to ease up on the brakes and let the bike flow. On gravel descents and flat sections, the vertical compliance really becomes noticeable. A lot of the high frequency vibrations that fatigue the hands and cause the back to stiffen are eliminated. Hard impacts are felt but they are dramatically muted. It is only in sharp corners that the Grade Carbon Ultegra is at a disadvantage. The longer wheelbase, taller head tube and less aggressive geometry limit its ability – although the wide 28c Continental Ultra tires provide excellent traction when leaning deep into corners.

The Line
Below the Grade Carbon Ultegra is the Grade Carbon 105, which comes equipped with Shimano 105 components. Next in line is the Grade Alloy X, which forgoes the carbon frame in favor of a 1350-gram alloy frame. It features Shimano Ultegra components. The rest of the line is comprised of the Grade Alloy 105, Grade Alloy Tiagra, Grade Alloy Sora and Grade Alloy Claris.

Grade Carbon Ultegra $3299
Grade Carbon 105 $2599
Grade Alloy X $1750
Grade Alloy 105 $ $1299
Grade Alloy Tiagra $1099
Grade Alloy Sora $899
Grade Alloy Claris $799