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MSRP for stock model:$4,500
MSRP for bike as tested (Aeolus 5 wheels): $6,550
Overall star rating: 4/5
What we like: Tight, quick steering; IsoSpeed decoupler adds comfort.
What we don’t like: QR rear wheel; plastic cap covering decoupler broke almost immediately.
Trek has committed to IsoSpeed for 2016, and its proprietary decoupler has appeared in various iterations on many of its most popular dirt and pavement bikes. The Boone 9 is no exception: The IsoSpeed decoupler is built into the frame to help add a splash of comfort to what ultimately seems to be a very stiff frame. The idea behind IsoSpeed is to allow flex in the seatpost without compromising stiffness in the bottom bracket area. This allows for as much pedal power transfer as possible without shaking your fillings loose when you’re in the saddle.
We’ve put some miles on the Boone both on and off the race course, and overall, we found it to be an excellent race bike: quick steering, instant acceleration, and comfort to boot. But it’s got some imperfections that should be addressed on future versions of the Boone.
We’ve mentioned in other reviews that IsoSpeed works, and this is the case with the Boone 9 as well: The decoupler quiets chattery courses so you can concentrate on pedaling hard and strategizing your next move around the guy ahead of you in the chicanes. We were a bit surprised, though, to see how quickly the bolt within the decoupler loosened. It took about five hard rides before we heard a noise and found that the bolts were not tight. The plastic cover, too, worked loose almost immediately and cracked. It’s a decorative piece, so no big deal in terms of functionality, but aesthetics matter when you’re paying this much for a bicycle. Once tightened, the decoupler didn’t work loose again.
Trek has added a thru-axle fork for 2016, though it stuck with a quick-release rear, a contentious choice when the stiffer 142×12 option is now available on so many bikes in this category. Aside from that complaint, the frame is spot-on: The geometry feels fairly compact, avoiding that long, laid-out position common on race CX bikes, which can compromise quick steering; the frame is, subjectively, quite stiff in the bottom bracket (we did not send this bike to the VeloLab for testing).
Despite all that stiffness, the Boone rarely feels harsh, which is likely attributed to the IsoSpeed. Up front, our best guess is there’s enough flex in the fork and head tube to keep the ride comfortable, but the thru-axle provides quick, accurate steering.
Our test bike came with Bontrager’s Aeolus 5 D3 TLR Disc wheels, which are not stock on this model, and while they’re stiff wheels that offer tubeless versatility, it isn’t worth pillaging your wallet for them. Tubeless-ready clinchers will run you $2,850 aftermarket for the set, while tubulars will set you back $2,400. We rode the clinchers with tubeless tires, and the set-up was ideal for many conditions but not necessarily the race course. You won’t get the low tire pressures you can with tubulars, but the peace of mind that came with tubeless, knowing punctures wouldn’t likely be an issue on terrain riddled with goat heads, definitely helped. Tubeless isn’t about to overtake tubulars in terms of overall usability and performance on the ‘cross course, so if really low pressures are your thing, or you fear burping a tire, you might want to consider the tubular version instead. For our money, we’d stick with Zipp 303 tubular discs, which are just as stiff, weigh slightly less, and actually cost less.
While Trek could stand to iron out a few kinks with the IsoSpeed, and the rear axle really should be a 142×12 thru-axle, the Boone 9 is an agile and fast racer that hits a price point lower than similar bikes in the category. We’d stick with the stock wheels to keep the price down, and invest in some tubulars for serious racing, but otherwise, out of the box the Boone 9 is serious about reaching the podium.