It hasn't exactly been a secret that Trek were working on a new XC race bike - a covered-up version of the bike was raced earlier this season, and that wrap was removed for World Champs in Mont-Sainte-Anne. The veil of secrecy has now been completely removed, revealing the new Supercaliber.
The bike replaces Trek's Top Fuel as the brand's World Cup XC full suspension race bike, with 60mm of rear travel delivered by their unique IsoStrut suspension system. The team at Trek claim that many cross-country riders are looking for a bike that rides like both a hardtail and a full-suspension bike all in one. There have been some attempts at this style of the bike in the past, most notably the STP from Trek nearly 20 years ago, but there were always some compromises with the performance.
Trek Supercaliber Details
• Intended use: XC Race
• Wheel size: 29"
• Travel: 60mm (rear) / 100mm fork
• Boost 12x148mm spacing
• Carbon frame
• Sizes S, M, ML, L, XL, XXL
• IsoStrut suspension
• Weight: 21 lbs
• Price as shown: $9,500 USD
• Frame only: $3,700 USD
• Available in November 2019
One of the biggest issues was that even with the shock firmed up or locked out a full-suspension bike inevitably still has flex in the rear end from all of the pivots. The Supercaliber is designed in a way to eliminate a lot of those problems and provide suspension with a pivot and the structural IsoStrut. The frame, including the shock and hardware tips the scale at 1900 grams.
The Supercaliber will be available only in carbon and in four different models, the 9.7, 9.8, 9.9, and a 9.9 AXS. Sizes S-XXL are available. The rear ends of the bikes are made and tuned according to the size of the frame, so Trek ended up producing four different rear ends for the bike.
In order to find out more, I headed to Waterloo, Wisconsin, to talk to the engineering team about how this bike came to be. Let's break things down and look at a couple different areas individually, starting with the IsoStrut.IsoStrut
Trek's IsoStrut serves multiple purposes - it contains an air spring and a damper, and also serves as a structural component of the frame. When photos of the Supercaliber first surfaced there was speculation that it worked as a pull shock, but the cutaway view reveals that that's not the case.The team at Trek spent the last four years prototyping and testing different designs before they settled on this final iteration. Key to the bike is Trek's collaboration with Fox. It was impossible to develop the frame without the strut, or the strut without the frame, so engineers had to work closely to figure things out.
The IsoStrut's air spring can be tuned and dialed in exactly how a rider desires, and it can be fully locked out. With the IsoStrut integrated into the bike as a structural component that carries top tube loads, it allows the Supercaliber to achieve stiffness numbers that are a lot higher than a typical full suspension bike. The shock has a 32.5mm stroke, which gives the bike a low 1.5-1 leverage rate. The shock and IsoStrut can be serviced with standard Fox parts.
The fact that there's no link to drive the IsoStrut shock is what sets it apart from a typical rear suspension design. Everything is built into a carbon fiber carriage which moves on 36mm bushings, and the shock is connected via hardware that runs through the center of that carriage, along with slide bushings that also prevent any rotation. Pivotless Seatstays
Seatstays on the bike are pivotless and flex to work with the suspension through a virtual pivot in the seatstay. There is 55mm of damped travel through the shock, and then there is an additional 5mm of travel from the seatstay bowing which also provides progression for the suspension.
A Long Process
Other Frame Features
The Supercaliber can handle up to a 120mm fork and has clearance for up to 2.2" tires. The bike fits two full-size water bottles, as any proper XC race bike should. There's internal cable routing throughout and the bike also has a 31.6 seat tube so riders have the option of standard dropper posts.
Trek's polarizing "Knock Block" that stops the handlebar controls from contacting the top tube is also present on the Supercaliber. It does serve a purpose - without it, the brake and shift levers would indeed contact the top tube if turned past 90-degrees.
The Supercaliber took over three years to go from inception to the finished product; engineers went back and forth on countless ideas and trial runs before settling on the final bike. That extended R&D period meant that more than a few frames designs never made it past the prototype stage - here are a few from along the way.Geometry
The Supercaliber has appropriate angles for an aggressive World Cup level XC race bike. The head tube sits at 69-degrees, the seat tube is 74-degrees, and the chain stays are 430mm.
I'm one of a very few outside of Trek's engineering and race team that has had the chance to ride the new Supercaliber. I rode the bike briefly at Trek's Waterloo, Wisconsin, headquarters and then have a few rides on it at home in North Carolina.
In the coming months, I'll do a full review once I've had a chance to get some additional miles in on the bike and fully assess its capabilities.Climbing
The Supercaliber is said to climb like a hardtail when it's locked out, with a flex-free rear end and a no movement from the shock. Does it deliver? Yes. Hit the lockout lever and the front and back end of the bike both lock out simultaneously, shifting the full-suspension rig into a fully rigid and very efficient mode. The bike climbs as well as you would expect a fully rigid bike to be. If this were my bike I'd be tempted to disconnect the front lockout in order to have a little more comfort when the shock was in full rigid mode, but I understand the dual lockout setup - in an XC race any excess motion is energy that could be used to stay ahead of the pack.
With the shock and fork open, the bike has gobs of traction heading uphill and minimal pedal feedback in the suspension. The climbing position is comfortable, and I couldn't ask much more out of a XC race bike.Descending
Descending, the Supercaliber is an impressive bike, and it's much more sure-footed technical terrain than a hardtail. The 60mm of travel out back feels closer to that of the Top Fuel, not nearly half of it. A lot of that can be attributed to the flex-stays. One thing that was stressed to me is how important the bike is to really take time on the set up since there is so little suspension out back, compared to most full-suspension bikes we're riding these days.
Setting up the shock differently can greatly change the ride feel, so much so that Trek include three different volume spacers with the bike so riders can fine tune the shock feel themselves right out of the box. It's a simple procedure - you simply unbolt the two front bolts on the IsoStrut and then open up the shock using an open faced BB tool. Add, remove, or swap a spacer, tighten back the can, air back up, and you're good to go. I've spent a bit of time moving spacers around and I can't stress enough how much a difference they make in tuning the way the Supercaliber rides.