My first impression of the 2019 Open UPPER gravel bike was truly hyperbolic. I stated to anyone following on Strava that it was “quite possibly the best bike I’d ever ridden. Full stop.” In other words, the best of hundreds of bikes I’ve ridden and reviewed over the past 20-plus years.
How can one really compare mountain bikes, road bikes and gravel bikes? It’s like trying to compare The Grateful Dead, Pearl Jam and Jay-Z. They’re all legendary artists but that’s where the similarities end. Nevertheless, my initial 30-mile ride on dirt and asphalt, where I crushed some PRs, compelled me to make this questionable claim.
After some self analysis, though, I realized that gravel riding in general and the Open UPPER in particular represent everything I love about cycling. It’s the speed and efficiency of road cycling combined with the dirt and remoteness of mountain biking. You’re in the drops, but there are no cars or traffic lights. You’re picking the fastest lines through rocks and ruts but from an aero position on a super-light bike. And you haven’t lived until you take a corner too hot and end up in a two-wheel drift on 40c tires.
The superlative sense I had for the Open didn’t come as a complete surprise. After all, I did set out to build the ultimate gravel bike. Having ridden a medium frame last year that proved too small, I had an idea of how well the bike would perform. When I finally built it up with hand-picked components, though, it far exceeded those expectations.
The Frame Set
The Open UPPER frame set ($4,500) is crafted with premium carbon fiber that makes for a durable-and-efficient yet supple-and-snappy ride. It’s everything you want in a gravel frame and nothing you don’t, as it tips the scales at a scant 890 grams. That’s why it costs more than most bikes. The less-expensive-but-by-no-means-cheap UP version of the frame set ($2,900) uses the same geometry and is just as durable, while utilizing a less costly grade of carbon fiber, and it weighs 1,040 grams.
The key feature of the frame is the no-compromise tire clearance. By dropping the drive side chainstay, it can accommodate treads ranging from skinny road tires (23c) to beefy gravel tires (40c) and even 650b (27.5”) mountain bike tires up to 2.1 inches. Utilizing its full range requires two sets of wheels, but it’s like having three different (very fast) bikes: road, gravel, and rigid mountain bike. This is all accomplished with a standard width bottom bracket to maintain pedaling integrity.
Design-wise, the UPPER features key details like a direct-mount front brake for a 160mm rotor...because what other size rotor would you run? The seat tube is designed for zero-offset seat posts...because why offset the seat post if you don’t have to? And the rear thru axle also serves to lock the derailleur hanger into the frame. The UP and UPPER are the result of decades of frame design and technological evolution.
In previous gravel bike reviews, I’ve used both the SRAM Force 1 mechanical and the eTap wireless electric drivetrains. This year SRAM somewhat married these into the new Force eTap AXS group. It uses the new AXS wireless shifting standard, which is available across multiple groups for road, gravel, cyclocross and mountain biking. And it’s available as both 2x and 1x configurations.
Since I lean toward the mountain biking side of the gravel equation, my feeling is that hardcore gravel bikes should be setup as 1x drivetrains. I’ve become accustomed to the simplicity and reliability when terrain gets rough. That’s why I liked the Force 1 mechanical group. It offers a 10-42t cassette, which enables you to swap out 38t, 40t and 44t front rings to accommodate pretty much any terrain. The problem with the new Force eTap AXS is that the largest range is a 10-33t cassette; this is reinforced by the limits of the rear derailleur. I rode it with a 40t ring for a couple months and often ran out of gear at both ends of the spectrum. Clearly, I needed more range to match the UPPER’s tremendous potential.
This lead me adopt one of the coolest drivetrain stories of the year: The Mullet Build. Starting as early as the Dirty Kanza, sponsored SRAM riders showed up with this breakthrough setup. It uses SRAM AXS road shifters in the front (the business end) paired to an Eagle AXS mountain bike cassette (10-51t), derailleur and chain in the back (the party end). This is possible because all of the AXS components are cross-compatible. It was just a matter of pairing the new derailleur to the shifters with a couple clicks. You can still swap the front chainring to tailor the gear range, but a 44t ring with 10-50t cassette is pretty much all I need.
However, the mullet was only available to mortal riders just recently, as you can now purchase individual SRAM AXS components as opposed to the whole group set. It’s key to note that the mullet build represents a rather expensive upgrade at more than $1,200 for the derailleur, cassette and chain. This is the price for the best gravel drivetrain on the market.
To optimize power transfer, I also opted for the Rotor 2INpower Direct Mount Crankset ($1,400). This is a dual-leg power meter, complete with its own mobile app, that can accommodate a range of chainrings in both 1x and 2x configurations. Rotor’s signature product, though, is its oval-shaped Q Rings ($130). Throughout the test I used both 40t and 44t rings, and they are very simple to swap out by using the included Rotor chainring tool. Finally, at the heart of the system is Rotor’s buttery smooth Ceramic Bottom Bracket ($219). The UPPER uses a BB386EVO pressfit bottom bracket standard, and Rotor makes one of the best versions. The cups thread together inside the frame for a solid and creak-free fit, and there’s nothing like the feeling of these bearings.
All of which contributed to amazing times and power output. Whether because of the oval rings, which compensate for weak spots in your pedal stroke, or the smooth bearings or just being so inspired by riding this bike, I consistently set not only Strava PRs but also maximum power PRs, otherwise known as Functional Threshold Power (FTP). It’s the maximum average power one can produce when going full gas for 20 minutes. This is the bike that set all of those high-water marks for me this season.
Finally, the Force AXS hydraulic disc brakes are outfitted with 160mm rotors front and rear. These are some of the easiest disc brakes to adjust and dial for individual preferences, and they offer more than enough stopping power for steep off-road descents. On several occasions, I could hear the rotors crackling from the heat buildup but never felt them fade in the least. The Force AXS brake hoods are also very chunky, which improves confidence and handling over jackhammer terrain.
Perhaps the most important component choice for a gravel bike is the handlebar. It’s the difference between bombing dirt descents with mountain-bike-like confidence and losing huge swaths of time in a race or worse, crashing out. Mountain bikers realized a while ago that wide bars equal better handling; today they come stock at 800mm in many cases. The gravel equivalent is the ENVE G Series Gravel Handlebar ($350), which is offered in four widths ranging from 42cm - 48cm at the hoods and 54cm - 60cm at the drops. Indeed, the drops flare out by 12cm. This gives you much more leverage over the front wheel when terrain is trying to whip it side to side.
Just as important is the bar tape. You want something that can absorb shock and vibration, especially if you’re planning to ride one of the 10-hour gravel epics. The Lizard Skins DSP Bar Tape V2 in the 3.4mm thickness ($44) is the best I’ve ridden, and it’s available in a range of colors.
The saddle is a Selle SMP Lite 309 with steel rails ($259). This is my choice for all off-road riding, as it balances support, padding and pedaling efficiency. Plus, it’s offered in a red colorway to match the bar tape, wheels and crank accents.
Finally, the choice of seatpost isn’t usually a big deal. But the FSA K-Force SB0 carbon ($233) meets the zero-offset specification for the UPPER while offering a simple-yet-effective clamping mechanism for getting saddle positioning just right for both standard and wide rails. It’s also quite light at just 228 grams.
Wheels and Tires
The Ultimate Gravel Bike necessarily includes two sets of wheels: 700c and 650b. The gravel universe is just too broad and variable for a single set. Plus, you can’t maximize the fun factor if you don’t have the right treads.
For the fastest uphill speed and hanging with the roadies, I chose the ENVE G23 700c wheels ($2,550). The set I have was previously featured on the Pivot Cycles Vault, so it’s not the current model year. The main difference this year is the choice of hubs. DT Swiss is no longer an option. It’s been replaced with Industry Nine and ENVE’s Alloy Hubs as options, in addition to Chris King. Otherwise, it’s the same 23mm internal rim width, which easily handles a 40c tire, in super-light package at about 1,300 grams for a set.
My 700c tire choice was the Maxxis Rambler 40c EXO/TR ($60). It features a fast-rolling center tread that also hooks up in the rear for out-of-the-saddle climbing on dirt surfaces. But the side treads are more aggressive for cornering. I feel like 40c is a Goldilocks size in that it’s light enough to be efficient but beefy enough to float over rocks at the lower end of its tire pressure range.
For more aggressive off-road riding — and having pure fun without thinking about PRs — the Zipp 303 Firecrest 650b Carbon Clincher ($2,500) serves as a hybrid of sorts between a road and mountain bike wheel. The internal width (21mm) is narrower than the G23 because it’s also designed for road tires. You can use these wheels to fit 28c tires in a bike that would otherwise max out at 25c. But you can also mount 27.5 x 2.1-inch mountain bike tires, which effectively makes the Open UPPER a rigid mountain bike with drop bars.
I’ve ridden the 700 x 40c version of the Schwalbe G-One Bite and liked how aggressive it is for pure off-road routes. It also has a 27.5 x 2.1 variant ($80) that I chose for the Zipp 303s. At 550 grams it’s pretty light for a tire with so much grip and volume. It also makes for a much more relaxed state of riding, as you’re not as concerned with choosing just the right line. It doesn’t react to the terrain as much as a 700 x 40c wheel and tire. It feels more at home on singletrack because you can better rely on its cornering grip and ability to absorb whatever the trail serves up.
The full Open UPPER build of the 700c version with Force eTap AXS weighs 17 pounds, 9 ounces. When I swap out for the mullet build and add the 650b wheels and tires, this grows to 18 pounds, 14 ounces. In other words, it’s comparable to race-level road bikes and makes for an incredibly fast ride on pretty much any surface. Personally, it sets the benchmark for fun when riding fast is the key factor.