Cyclocross Race Bike Shootout: Trek Boone 9 Disc Review

Versatile bike with exceptional compliant ride and top-end parts

Cross Disc
Trek Boone 9 Disc Review

For races, we swapped back and forth between the stock HED Ardennes+ wheels and the pictured Roval tubulars.

Editor’s Note: This article is part of our 2014 Cyclocross Race Bike Shootout series, which also includes reviews of top competition steeds from Jamis, Specialized, and Van Dessel, as well as a SRAM Force CX1, and tests of several wheelsets and ’cross tires.

Racing cyclocross presents a beguiling paradox of performance needs. In a perfect world your bike would possess the light weight, stiffness and efficiency of a Tour de France-worthy road steed mixed with the cushion of a full-suspension cross-country mountain bike. But the world of ’cross is not perfect, nor has the cycling industry learned how to violate the laws of physics.

Instead, we’re left with compromises. Frames are stiff enough for hammering up hills or down straightaways, and hopefully still offer some semblance of compliance for the occasional bumpy grass, ice ruts, dirt jumps, or whatever else is thrown your way. It’s far from ideal, and requires even the casual weekend warrior to give tubular tire set-ups serious consideration because of the benefits of better traction and ride smoothing.

Trek Boone 9 Disc Review

The IsoSpeed decoupler is essentially a small amount of suspension in the form of a unique seat tube-top tube junction that allows the bike to flex under impact.

Enter the Trek Boone, which attempts to solve (or at least address) these problems with its IsoSpeed decoupler. For the layman the decoupler is essentially a small amount of rear suspension in the form of a unique seat tube-top tube junction that allows the bike to flex under impact. It’s the same technology Trek uses on its Domane endurance road frames, which have been raced extensively at the sport’s highest level on the rough cobbles of northern France and Belgium.

We’ve been riding and racing the top-of-the-line $6300 Boone 9 Disc for about two months now and been roundly impressed. Subtle flex in the frame accompanied by a similarly behaving IsoSpeed (aka tapered) fork nets a cyclocross bike that simply feels smoother than any other we’ve ridden.

The difference is not overwhelming, but it’s certainly noticeable both at the point of impact, and at the end of races when the body feels a little fresher because it hasn’t taken such a beating. Instead of being tossed around through the rough stuff, wheels and traction remain intact, which means more seated pedaling and less coasting while standing.

Frame geometry also lends to this smoother, controlled ride. The Boone is slightly less aggressive than the other bikes we’ve been testing this fall. Our size 58cm rig has 1028mm wheelbase (longest in the test) and 65mm bottom bracket drop (lowest in the test). Add in the slightly slacker head tube angle, and you get a bike that’s more Cadillac than Corvette. The Boone isn’t as snappy a turner as the other bikes in this test, but it tracks like a train at high speed.

Here’s a look at several key metrics from three size 58cm bikes in this test.

Specs

Trek Boone 9 Disc Review

Trek’s Boone 9 Disc, MSRP: $6300

Stop and Go

With its $6000-plus price tag, parts spec on the Boone 9 Disc is primarily top shelf. Shifting and propulsion are controlled by an internally routed Shimano Ultegra Di2 electronic drivetrain. As we wrote in our test of the similarly spec’d Specialized Crux Pro Race, we were initially skeptical about the necessity of Di2 for ’cross. But we’ve quickly grown to love the speedy and precise performance. On courses with rapid transitions from fast to slow, you can pedal longer in a big gear, then quickly move the chain up the cassette or into the small chainring in time to tackle a steep section.

The electronic shifting buttons don’t provide the tactile feedback of traditional levers. But that wasn’t necessarily a bad thing, just something you had to get used to. The lone negative experience came during one snowy, cold race that necessitated thick gloves. This led to the occasional miss-shift, maybe 3-4 times out of 50. But with a little more practice, we’re confident we could get that number to zero.

Chain security has also proven reliable. In two months of racing, training, and occasionally crashing, we’ve yet to drop the chain. That’s achieved in part by the flawless and smooth electronic shifting between 46- and 36-tooth chainrings, and Trek’s 3S chain keeper that’s integrated directly into the frame.

Trek Boone 9 Disc Review

Trek’s 3S chain keeper is integrated directly into the frame.

Shimano also takes care of braking in the form of its superb R785 hydraulic disc set-up. If you haven’t ridden disc brakes for ’cross yet, you’re missing out. The ability to carry speed into corners and steep descents, then quickly throttle back in a controlled and precise manner is huge. Of course we’d like to see Trek adopt a thru-axle set-up, which would help address occasional bouts of rotor ting and increase front-end stiffness and steering precision. But rotor noise issues were only sporadic with the Boone and could usually be ameliorated with a quick caliper adjustment.

Occasional Shuddering

One thing we could not completely remedy, though, was fork shudder, which occasionally cropped up during times of heavy braking, especially on steep downhills when there was more weight on the front end. It’s hard to say exactly how big a problem this is, because during a hot laps session with multiple riders testing the bike, some suffered dramatic shudder, while others had no issues at all. Our best guess is that riding style was in play here. Some riders tend to dig hard into the brakes, while others use a more feathery touch.

Just to be sure it wasn’t a set-up issue, we had former WorldTour mechanic Daimeon Shanks examine our test bike. Shanks found no problems and surmised that the fork’s narrower profile and compliance-enhancing sweep were partially at fault. “The fork is designed to be compliant and soak up bumps,” said Shanks, who runs the Service Course, a well-regarded Boulder, Colorado-based bike mechanic business. “The trade off is that under heavy braking load you can get some flex to the point of elasticity, and then it snaps back, which is the shudder.”

Trek Boone 9 Disc Review

Rotors are 160mm front and rear. The fork has an extra curve above the drop-out that creates a smaller angle in the direction of road vibration, which is claimed to increase fore/aft compliance.

Shanks added that the stock 160mm Shimano XT level rotors are arguably too powerful and could also be a contributing factor. The good news is that the Boone is compatible with 160mm or 140mm rotors, which would offer slightly less braking power, but could also reduce the chance of fork shudder. “For ’cross I don’t think dropping down to a 140mm rotor would make any difference,” added Shanks. “And it could solve the shudder problem.”

For comparison sake, the Specialized Crux Pro Race comes with 140mm Shimano IceTech rotors front and rear, while the SRAM CX1 spec’d Jamis Supernova Team with a front thru-axle has 160mm front and 140mm rear. We experienced no fork shudder aboard either of those bikes during testing.

Finally, brake pad compound can also be a culprit, but the Boone is spec’d with metal pads, which have less initial bite but last longer than more grippy resin pads. Bottom line, it wasn’t a deal breaker by any stretch, and never effected us during a race, but it’s something any prospective Boone owner should be aware of.

Trek Boone 9 Disc Review

If you prefer a 140mm rotor (we would) simply remove the pictured spacing adapter.

Tubeless Ready

The rest of the Boone 9 Disc’s parts spec is in line with what you’d expect for a bike in this price range. The 25mm-wide HED Ardennes+ wheelset are plenty stiff and spin up fast. More importantly they’re tubeless ready so you can use them for training and racing without fear of pinch flats.

We weren’t as impressed with the stock 32c Bontrager CX3 Team Issue tires, which are too narrow for our liking and were tough to set up tubeless. During races, we either used a set of carbon Roval tubulars wrapped with Challenge Fango tires, or ran the HED’s with a set of toothier and wider 33c Vittoria Cross XL Pro tubeless tires that were much easier to set up.

Trek Boone 9 Disc Review

We weren’t particularly impressed with the 32c Bontrager CX3 Team Issue tires, which are too narrow for our liking.

The rest of the bike is dressed with functional Bontrager components highlighted by the Bontrager ride tuned carbon seatmast, which has a no-cut design that eliminates traditional seatpost clamping forces. This allows for less material at the seat tube junction, which in turn reduces weight. Our tester came in at 18.3 pounds without pedals. The seatmast has 10cm of adjustment, which should be enough for most riders. Our size 58cm tester, for example, would accommodate saddle height as low as 78cm.

No discussion of the Boone would be complete without addressing its versatility. While the other bikes in this test were purpose-built cyclocross race bikes, we could easily envision the Boone serving multiple two-wheeled purposes. Indeed, with its disc brakes and slightly more relaxed geometry, it could be a great do-it-all drop-bar rig for the rider with limited budget or garage space. Gravel grinding, casual road riding, light duty singletrack, even commuting are all in the realm of functional possibility. We got the Boone up to near 50mph on one of our go-to paved descents and felt completely comfortable and stable. And the frame has discreet fender mounts if you want to go that route.

Trek Boone 9 Disc Review

Remounts are a little softer thanks to the Bontrager Evoke 3 saddle — and the IsoSpeed decoupler.

Hot Lapping

To add some diversity of opinion to our test, we enlisted a half dozen upper-level amateur racers and spent a day spinning hot laps on the Valmont Bike Park cyclocross course in Boulder, Colorado. Trek’s Boone 9 Disc drew primarily positive reviews.

“You definitely feel the decoupler,” said one cat. 2 masters racer. “It does a nice job of taking the little hits out. But I did get a little shudder. To me, the fork just looks a little undersized.”

“The Trek rides a little taller than the Specialized [Crux Pro Race],” said another tester. “So for me it was a little less nimble in the tight stuff, but smoother on rough terrain and at speed.”

“[The Trek] was my favorite of the three,” said another tester. “I really felt the compliance of the decoupler, and the bike just felt really fast and smooth, especially out of the saddle.”

“It’s kind of a toss up of what’s most important to you,” said a another tester, who’s a former Colorado state master cyclocross champion. “I’d opt for the Boone over the Specialized [Crux Pro Race]. It doesn’t accelerate quite as well and it’s not as snappy, but it’s so much more forgiving. It just takes the edge off everything, which can be a huge benefit at the end of a race when you’ve been getting the s–t beat out of you.”

Trek Boone 9 Disc Review

The 25mm-wide HED Ardennes + wheelset are plenty stiff and spin up fast. More importantly they’re tubeless ready.

Bottom Line

If you’re in search of a purebred cyclocross competition steed that handles like a Maserati (with the lack of suspension to match), the Boone may feel slightly sluggish and soft. For anyone else, this is an exceptional race bike with a compliant ride, great parts spec, and the ability to do double duty as an “adventure” roadster. Indeed, if we could own only one drop-bar bike, the Boone just might be the one.

Pros
  • Smooth ride on bumpy terrain
  • Stable predictable handling
  • Reliable and precise electronic shifting
  • Great braking control and modulation
  • Integrated chain catcher
  • Flattened top tube for ease of shouldering
  • Hydraulic brake hoods enhance hand grip
  • Tubeless ready wheels
  • Versatility of uses
Cons
  • Occasional fork shudder
  • 160mm rotors are overkill for cross racing
  • Potential for accidental shifts when shouldering
  • Maintaining rotor-pad tolerances
  • Steering not as snappy as some CX race bikes
  • Slower acceleration
  • Narrow tires
  • High price
Trek Boone 9 Disc Review

The Boone proved plenty stiff under power, but was a little slower from a standstill than other bikes in this test.

Trek Boone Disc 9 Specs
  • Price: $6300
  • Weight: 18.3 pounds
  • Frame: 600 Series OCLV Carbon, IsoSpeed, Ride Tuned seatmast, disc balanced post mount, E2 tapered head tube, BB90, internal control routing, 3S chain keeper, vanishing fender mounts
  • Fork: Trek IsoSpeed Cross carbon disc, E2
  • Front Derailleur: Shimano Ultegra Di2, braze-on
  • Rear Derailleur: Shimano Ultegra Di2
  • Crankset: Shimano Ultegra, 46/36
  • Cassette: Shimano Ultegra 11-28, 11 speed
  • Chain: Shimano Ultegra
  • Brakes: Shimano RS785 hydraulic disc, 160mm rotors
  • Shifters: Shimano RS785 hydraulic Di2, 11 speed
  • Rotors: Shimano RS785 160mm rotors
  • Wheels: HED Ardennes + centerlock disc
  • Tires: Bontrager CX3 Team Issue, 700x32c
  • Bars: Bontrager Race Lite IsoZone, VR-CF, 31.8mm
  • Stem: Bontrager Race X Lite, 31.8mm, 7 degree
  • Seatpost: Bontrager Ride Tuned Carbon seatmast cap, 20mm offset
  • Saddle: Bontrager Evoke 3, hollow titanium rails
Overall Rating

4 out of 5 Stars

For more information visit www.trekbikes.com.

About the author: Jason Sumner

An avid cyclist, Jason Sumner has been writing about two-wheeled pursuits of all kinds since 1999. He’s covered the Tour de France, the Olympic Games, and dozens of other international cycling events. He also likes to throw himself into the fray, penning first-person accounts of cycling adventures all over the globe. Sumner, who joined the RoadBikeReview.com / Mtbr.com staff in 2013, has also done extensive gear testing and is the author of the cycling guide book "75 Classic Rides: Colorado." When not writing or riding, the native Coloradoan can be found enjoying time with his wife Lisa and daughter Cora.


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  • TahoeSteve says:

    So wow, a special frame decoupler to add in a little movement/compliance. Glad they super-scienced that into a carbon frame, otherwise people wanting a CX bike that didn’t destroy their low back might have to resort to something terrible like a steel or Ti bike. 😉

    • BaronKarza says:

      I’d love to love a steel ‘cross bike. But since I barely outweigh a gnat, and steel tubing is built for Joe-average Americans (185 lbs), I find that steel bikes hammer the fillings out of my teeth while my larger competitors make comments just like you did.
      I researched the cost of a custom-geometry, custom-drawn-tubing steel ‘cross frame, and the pricetag was astoundingly high. A Ti ‘cross bike, even moreso! I still wind up with a heavier bike with both options.
      Sometimes, carbon fiber really gives you everything you want, even in a ‘cross rig.
      Also: I’ll look into smaller rotors as per Steve. 160mm rotors really do seem like overkill for a ‘cross bike being powered by a 120 lb ex-marathoner.

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