Wednesday, July 30, 2008
Top Fuel Gets More Top And More Fuel
Trek has dropped a substantial amount of weight from its 100mm-travel Top Fuel cross-country platform but also significantly improved its rear suspension performance at the same time. Add in the new model's radically extended seat tube and unique 'Cross Bow' frame design and the result is one of the most dramatic set of curves we've seen in a race-ready mountain bike in some time.
According to Trek product manager John Riley, the new carbon fiber frame is now just 2027g (4.47lb) for an unpainted 19.5in production sample with shock and seatpost, a full 431g (0.95lb) lighter than last year's equivalently configured version. Add in some careful component choices and the complete top-end 9.9 SSL model is just 9.5kg (21lb) without pedals.
Trek borrowed several technologies and concepts from its road-going Madone to save the weight, such as the 'no-cut' seatmast concept that has been adapted for off-road use. The Top Fuel version is really more of an extended conventional seat tube though, complete with a short seatpost. Trek says the reduced amount of overlap saves 100g but the oversized dimensions (the short seatpost measures 34mm in diameter) yield an 11 percent stiffness improvement in that area. Trek will offer both 185mm- and 245mm-long posts, too, both with 100mm of vertical adjustment.
The Madone also lends its integrated bottom bracket shell design with drop-in bearings but Trek even carries over its narrower road-standard bearing spacing. The 5mm-narrower dimension allows for a Trek-exclusive FSA 2x9 crankset on the 9.9 SSL that closely emulates the width of road cranks so that racers don't have to adapt when swapping back and forth. Even so, adapters thankfully enable the use of standard three-ring mountain bike cranksets.
In addition, the net moulding and Precision Fit Socket drop-in bearing concept is carried over to the suspension pivot hard points as found on the new Fuel EX and the integrated headset while a burlier one-piece magnesium Evo Link replaces last year's two-piece aluminium design to drop 75g.
New lightweight Bontrager XR Team Edition tyres also account for some of the weight loss, as does the use of a DT Swiss carbon-bodied rear shock, and new Bontrager Race XXX Lite wheels with carbon rims.
Not just lighter but better, too
The new Top Fuel is clearly lighter but suspension performance on the new bike should be greatly improved as well. The Full Floater rear shock configuration should provide the same well-tuned feel as on the now-proven Fuel EX and the ABP (Active Braking Pivot) floating brake design should yield better braking performance, particularly on washboard and braking bumps. Travel has also increased to 100mm.
Moreover, Trek claims that the new Top Fuel is a full 33 percent more rigid than the previous iteration, thus making it lighter, more capable and faster overall. Sadly though, we weren't able to verify the latter claims as Trek didn't have production samples available for test ride but we should be able to get our hands on one soon enough.
Of course all this technology won't be cheap: the Top Fuel 9.9 SSL will retail around US$7,500.
Fortunately for privateer racers and non-trustafarians there will be aluminium versions, Top Fuel 8 and 9, and a lesser-specced carbon framed Top Fuel 9.8 at less painful prices.