Aero Tuning Makes the New Trek Émonda Faster Than Ever

Photo credit: Matt Phillips
Photo credit: Matt Phillips


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The Takeaway: The Émonda SLR is a benchmark pro race bike—and it’s surprisingly rider friendly.

  • It has 183 grams less drag than the previous generation, but the frame is only 33 grams heavier

  • There are 10 models starting at $2,699

  • SL models ($2,699 to $5,999) have the aerodynamic shaping and features but in a frame that’s about 400 grams heavier than the SLR

  • SLR models ($6,699 and up) use a new carbon fiber composite that’s 30 percent stronger than Trek’s previous top-of-the-line carbon.

Price: $11,999 as tested (Émonda SLR 9 eTap)
Weight: 14.75 lb. (54cm)

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Update: On August 25, 2022, Trek Bicycles and the CPSC announced a recall of this Émonda SLR model to address an issue with the Bontrager Aeolus RSL VR-C handlebar and stem. The bike's carbon handlebar/stem can crack if overloaded, causing the rider to lose control of the bike. Customers are asked to stop using the bike and to contact their local Trek dealer.

For Émonda SLR bicycles, Trek will provide an individual handlebar and stem until an updated handlebar/stem combo is available.

Additionally, all customers who bring in their handlebars for replacement will also receive a $100 in-store credit that can be used toward any Trek or Bontrager merchandise through December 31, 2022.


Remember professional road racing? It’s that thing where super skinny people go unbelievably fast up and down hills and fly over flat roads for hours at a time. It’s been a while since the pros have beat up on each other for our entertainment, but there might, hopefully, be some races on the horizon. When the races do resume, Trek’s pro riders will be aboard its new third-generation Émonda climbing bike. The new Émonda isn’t lighter, but it is faster thanks to a dose of aerodynamic tuning.


—Five Cool Details—


Making the new Émonda frame more aerodynamic wasn’t exactly a tough hurdle as the previous Émonda had virtually zero aerodynamic optimization. But adding meaningful aerodynamic benefit while achieving the frame stiffness expected of a pro-caliber race bike, maintaining the well-regarded handling properties of the previous Émonda, and adding rider-friendly features like a threaded bottom bracket—all with adding only 33 grams (SLR frame, claimed)—is quite a feat.

Below you’ll find my review of the Émonda SLR—I’ve been on it since early March—followed by a dive into the technology and features of the new bike, and a brief model breakdown.

Ride Impressions: Émonda SLR 9 eTap

Photo credit: Matt Phillips
Photo credit: Matt Phillips

The Émonda SLR is a tool made to fulfill the needs of some of the world’s best road racers. This bike will never be as comfortable or versatile as a gravel bike. Going fast on pavement and climbing performance are its only goals. These are obvious facts, but that’s the lens through which it must be viewed. And through this lens, it is one of the very best.

The new Émonda was born out of a request from Trek’s pro racers and pitched as the company’s “fastest climbing bike ever.” So little surprise they set me up with the lightest model (the SLR 9 with SRAM Red eTap), which also has a build kit almost identical to the team’s bikes. It’s also, excepting customized Project One builds, the most expensive model at a buck under 12 grand.

That massive pile of clams gets you an aerodynamic frame with disc brakes, power meter, and wireless electronic shifting that weighs less than 15 pounds (54cm). And that’s with a hefty T47 threaded bottom bracket unit, lustrous paint, clincher wheelset, a chain-watcher, standard butyl tubes, 37mm deep rims, 160mm disc rotors front and rear, and SRAM’s largest Red cassette (10-33). That’s “Holy shit!” impressive.

By cutting drag a ton without adding much weight, it’s hard to argue with Trek’s claim that the new Émonda is faster than the outgoing generation. But if you have any doubts, they’ll be erased when you ride it. This is an explosive bike: it feels as light as a feather and as solid as a steel girder at the same time.

Photo credit: Matt Phillips
Photo credit: Matt Phillips

Trek’s Émonda has always been a raw and rowdy bike that feels a little wild and a bit dangerous in precisely the ways you want a race bike to feel: That’s not lost with the added aerodynamics. If anything, the new Émonda is even crisper and punchier than before, which is saying something.

A small downside to all this fury is the Émonda’s smoothness. Light and stiff race bikes aren’t a smooth-riding lot to begin with, but even measured against a stiffer riding genre, the new Émonda is on the firmer end of the scale. Still, it escapes harsh or punishing labels—I did a six-hour ride on the Émonda on the stock 25 tires and didn’t feel worn down by its ride. Swapping to 28s helped a lot (no surprise) and were on the Émonda for the bulk of my testing. I’d suggest reserving the lighter and more aerodynamic stock 25s for racing or PR attempts—assuming good roads—and use 28s as daily drivers.

The Émonda’s handling is excellent. Well, let me caveat that: Road racing geometry is pretty uniform, so whether I’m on a current race bike from Trek, Specialized, Cannondale, Cervélo, Canyon, Colnago, Wilier, Pinarello, BMC, Giant (etc., etc.), I find the broad strokes of their handling feel and performance quite similar. There wasn’t anything about the Émonda’s handling or cornering performance that set any new benchmarks for me, but there wasn’t anything to dislike either.

Photo credit: Matt Phillips
Photo credit: Matt Phillips

It was quick and accurate, diving into corners with a light touch. It offered great feedback, so I always knew where I was relative to its and my limits, and I could count on it to be consistent and predictable. It was maybe a touch less settled in bumpy corners than the Specialized Tarmac, but the Émonda never broke traction or skipped. Overall, for such a light bike, the Émonda is remarkably solid and drama free. I’d have no qualms barreling down a technical alpine descent on the Émonda.

I received this test bike in early March, giving me plenty of time to ride it back to back with its primary competition—a Specialized S-Works Tarmac, what I consider the benchmark for aero-ized lightweight bikes. The Tarmac is smoother over the bumps and has a silkier feel overall, but the new Émonda feels more efficient, like it can go faster more easily.

I’ve also ridden a good slice of the Émonda’s competition, including the Canyon Ultimate CF SLX, Colnago V3Rs, Cannondale SuperSix Evo, Cervélo R5, Wilier Zero SLR, Pinarello Dogma F12. These are all superb bikes, but I feel the Émonda is the class leader. It feels sharper and more explosive than all of them. It feels faster, and that’s what matters most in a race bike. But I also like that the Émonda is pretty straightforward and rider-friendly.

Photo credit: Matt Phillips
Photo credit: Matt Phillips

For example, I swapped the stock one-piece bar/stem for a standard stem and round bar. One, I could run a standard bar and stem on this bike, which you can’t say about every modern race bike. And two, I didn’t have to pull any cables, wires, or hoses to make the swap: Again, something you can’t say about all race bikes. For the record, the shape of the one-piece Aeolus bar/stem is great, and the tops are the most comfortable to grab of all the aero-topped bars I've used. The only reason I swapped is my preferred length and width combination (110x40) wasn't available yet.

The BB is threaded, which makes it easier to service and replace than a press-fit (however, I was getting some noise out of the BB area, which I never resolved). The wheels employ standard offset, and it uses regular thru-axles. It’s compatible with pod-style power meters and mechanical shifting. Its signature seat mast is pretty much the only non-standard thing about this frame, and even then, it’s pretty user-friendly. There’s no cutting necessary, height adjustment is ample, the saddle clamp is easy to use, and it’s travel-case friendly.

Photo credit: Matt Phillips
Photo credit: Matt Phillips

I expect so much from a modern high-end pro-level road racing bike that it’s hard to exceed those expectations. It’s rare when a bike does: The Émonda SLR is one of those rare bikes.

Team Request

The new Émonda is partially a result of a request from the Trek-Segafredo race team. “They are one of our primary customers,” said Jordan Roessingh, Trek’s director of road product. “And they started to realize that it’s not just weight, it’s not just stiffness and responsiveness, there’s this other thing—aerodynamics and speed—that’s also really important to be competitive and be faster on the bike. They had been one of the loudest voices saying, ‘We need the lightest-weight, stiffest bike possible.’ And now they started coming back saying ‘We need those things, but we also need the bike to be faster in order for us to be really competitive.’ ”

It is (comparatively) easy to make a light frame, it is easy to make a stiff frame, it is easy to make an aerodynamic frame. Making a frame that’s two of those three things is more challenging: Making a bike more aerodynamic usually makes it heavier, making a bike lighter typically makes it less stiff, etc. Making a frame that is light AND stiff AND aerodynamic enough to satisfy the demands of a top-level professional race team is extremely difficult.

Photo credit: Matt Phillips
Photo credit: Matt Phillips

But not impossible. Many brands already make a light, stiff, and aero bike. The Specialized Tarmac is one, as are the Canyon Ultimate, the Cannondale SuperSix Evo, the Cervélo R5, the Wilier Zero SLR, the Pinarello F12, the Scott Addict, and the new Giant TCR. All of them seek to balance the three qualities—light, stiff, and aero—in the pursuit of the ideal race bike, and they all manage the balance differently. The common thread between these bikes: They’re all used by teams that compete against Trek-Segafredo.

Still Light, Now With Aero

The previous generation Émonda SLR Disc, launched in 2017, was an extremely light frame at 665 grams (claimed). But when a frame is already that light, it is much harder to make it even lighter. At least lighter enough to make a meaningful difference.

Photo credit: courtesuy
Photo credit: courtesuy

So, Trek took a different approach to making its climbing bike faster—instead of lighter, it made it more aerodynamic. The new Émonda frame is a touch heavier—yet still extremely light at 698 grams—but the bike has 183 grams less drag than the previous generation.

The important thing to note here is that, though the frame is more aerodynamic, the 183 gram drag reduction is not from the frame only. New wheels and a new aero bar (more info on both below) play a role. The specific setups Trek used to get that 183 gram number are: 2018 Émonda with 28mm-deep Bontrager XXX 2 wheels, and Bontrager XXX Bar/Stem Combo compared to the 2021 Émonda with 37mm deep Bontrager Aeolus RSL 37 Wheels and Bontrager Aeolus RSL Bar/Stem Combo.

Photo credit: Matt Phillips
Photo credit: Matt Phillips

Another drag saving upgrade: the housing, hoses and wires for the controls are almost fully inside the frame. They dive into the frame at the head tube passing through the upper headset bearing. The front brake hose runs into the fork steerer and down the left leg before popping out just above the brake caliper. The fork steerer’s flattened sides provide room for the rear brake hose and derailleur control lines to travel down and into the frame. Though it has flattened sides, the fork steerer is still compatible with standard 1 1/8” stems.

The overall drag reduction results in a bike that is 18 seconds per hour faster when climbing an 8.1 percent grade (the average grade of Alpe d’Huez), and 60 seconds per hour faster on flat roads than the previous Émonda. Trek also claims the new Émonda is 13 seconds per hour faster than a Specialized Tarmac when climbing an 8.1 percent grade (all assuming the rider maintains a constant 350 watts).

Eight Point One Percent

With three qualities—aero, stiffness, weight—that work in opposition to each other, how do you decide how much to optimize one quality when you know it will negatively affect the other two? How aero is aero enough? At what point is improved aerodynamics offset by the weight added to get there?

The team behind the Émonda used a legendary climb to help them decide: Alpe d’Huez. “It represents an extreme example of what most people see on a regular basis when they’re doing a big climbing ride,” said Roessingh, “It’s around an 8 percent grade, and it’s about an hour-long climb for the pros—amateurs might go a little slower. It gives us a good understanding of what the benefit of a drag savings is relative to a weight savings.”

Photo credit: Matt Phillips
Photo credit: Matt Phillips

By optimizing the weight and aerodynamic balance around this climb, Roessingh claims the Émonda is faster on Alpe d’Huez and also faster on everything shallower than the famous climb, “which is the vast majority of the environments that most riders are going to ride in, including the team,” said Roessingh. “So if we can say it’s faster up Alpe d’Huez, it’s going to be significantly faster everywhere because the flatter it is, the more aerodynamics benefit you.”

Computer-Aided Optimization

Achieving the weight to the aerodynamic balance of the new Émonda required careful design of each tube shape. Aiding the Émonda’s team was supercomputing horsepower. The abridged and simplified version of the process goes like this: into the computer was fed a rough draft of the shape based on Trek’s aerodynamic experience and other information like UCI regulations. The program then varies the tube’s parameters within a predefined range and spit back several iterations of the shape, each with a different weight to aerodynamic balance. The Émonda’s team evaluated the alternatives and picked the one most suited to its location in the frame and best able to help the frame achieve its overarching goal.

Roessingh says that Trek cannot afford to buy the computing hardware necessary to run the CFD and FEA optimizations (in a timely manner) that helped shape the new Émonda’s tubes. The processing happens in the cloud where Trek rents time on Google, Microsoft, or Amazon’s supercomputers. It’s more affordable than buying a supercomputer. Even so, it is not cheap, “Cloud computing is becoming a relatively significant budget line item for us because we’re doing so many of these optimizations in CFD and FEA and all that processing happens in the cloud.”

Photo credit: Courtesy
Photo credit: Courtesy

The new Émonda’s fork legs, head tube, down tube, seat tube, and seat stays all use a variation of a truncated airfoil. The top tube and chainstays, which have virtually no effect on drag, are optimized almost entirely for stiffness to weight.

In Trek’s line, the new Émonda’s aerodynamic performance is equal to the third generation Domane; the Madone is still significantly more aero. But while the more aerodynamic Madone is faster in flatter terrain, once the climb hits about 5.5 percent, the lighter Émonda becomes the faster bike. And for many of the Trek-Segafredo team riders—and many amateurs—that means the Émonda is fastest when it matters most: the hardest part of a race or ride, which is almost always on a steep climb.

Photo credit: Matt Phillips
Photo credit: Matt Phillips

OCLV 800 Carbon

Getting the new Émonda SLR to be as light as it is while adding aerodynamic shaping would not be possible without employing a new carbon-fiber composite, said Roessingh. The new OCLV 800 composite is 30 percent stronger than Trek’s previous top-of-the-line composite (OCLV 700). Because it is stronger, they can use less: By using OCLV 800, Trek’s team was able to make the Émonda SLR frame 60 grams lighter than if they used OCLV 700.

Émonda SL

Photo credit: Courtesy
Photo credit: Courtesy

The Émonda SLR is very cool, but it’s also very expensive (bike prices start at $6,699). For the 99 percenters, there’s the Émonda SL (models start at $2,699).

The SL uses OCLV 500 composite, and the frame is quite a bit heavier than the SLR’s. The SL’s frame comes in at 1,142 grams, with a 380-gram fork (SLR fork weight: 365 grams).

But material (and weight) are the only difference between the SL and SLR.

Aeolus Bar Stem

While a ton of work made the Émonda’s frame tubes faster, a big chunk of the new bike’s drag savings comes from the one-piece Aeolus bar stem. It alone is responsible for 70 grams of the Émonda’s 183-gram drag reduction. This means that if a traditional stem and round bar are installed on the new Émonda, its drag advantage over the previous-generation bike drops to 113 grams. And it means that you can make any bike with a round bar and traditional stem significantly more aerodynamic by merely installing the Aeolus. Retail price is $650.

Photo credit: Matt Phillips
Photo credit: Matt Phillips

The integrated Aeolus is made of carbon-fiber composite, of course, with a claimed weight of 297 grams (42x120). It’s offered in 14 length and width combinations, from 44x120 to 38x80. Hoses, housing, and wires run externally for easier service and repairs, but in a groove that keeps them out of the wind. A bolt-on plate keeps the control lines tucked and organized where they turn off the bar tops to run in line with the stem.

The Aeolus employs a mount that works with Bontrager’s line of Blendr accessories for mounting computers and lights.

Aeolus 37 Wheels

Another new Bontrager product rolling out with the Émonda is the Aeolus 37 wheelset. It comes in two models: the Aeolus RSL 37 (1,325 grams/pair, $2,400) and the Aeolus Pro 37 (1,505 grams/pair, $1,300).

Photo credit: Matt Phillips
Photo credit: Matt Phillips

The RSL 37 is claimed to be lighter than Zipp’s 32mm-deep 202, yet more aerodynamic and more stable than Zipp’s 45mm-deep 303. Both wheels are disc brake only (only Center Lock interface), tubeless compatible, use DT-Swiss internals, have no rider weight limit, and come with a lifetime warranty.

Surprisingly Rider Friendly

Though the new Émonda is clean and integrated looking and uses high-performance standards, it is also remarkably rider-friendly. Cables, hoses, and housing run externally on the one-piece Aeolus bar/stem for easier repair and service (with one exception: wiring for a Shimano Di2 or Campagnolo EPS bar-end junction box runs partially inside the bar). If you prefer a more traditional cockpit, it can be run with a standard bar and stem with 1⅛-inch steerer clamp.

The bottom bracket uses the threaded T47 standard, which is compatible with almost all common crank-axle standards.

Photo credit: Matt Phillips
Photo credit: Matt Phillips

Front and rear thru-axles are standard 12x100 and 12x142mm, and the wheels employ a standard dish. The standard flat mounts for the brake calipers are compatible with 140, 160, or 180mm rotors.

Tire clearance is officially 28mm, but that’s with a ton of extra space. I fit 32mm tires in the Émonda with ease.

And though all models do use a seat mast, it’s a no-cut variety with lots of adjustment range.

H1.5 Geometry

Trek did offer its top-of-the-line race bikes in the aggressive H1 geometry for riders seeking an ultra-long and low geometry, or H2 which was an endurance fit. The new Émonda is offered only in H1.5, which splits the difference between H1 and H2. The result is pretty typical dimensions for a modern race bike—a 54cm Émonda H1’s geometry is remarkably similar to a 54cm Specialized Tarmac.

There are eight sizes starting at 47cm and topping out at 62cm.

Models

Photo credit: courtesy
Photo credit: courtesy

There are 10 models of the new Émonda. SL models start at $2,699 and are priced up to $5,999. SLR models start at $6,699 and go up to $11,999.

Only SLR models come with the Aeolus integrated bar/stem stock; and only the Émonda SL 7 ($5,499) and up come with the Aeolus 37 wheelset.

The new Émonda is a disc brake-only platform.

Project One

The new Émonda is in Trek’s Project One paint and parts personalization program. If that’s not luxe enough for you, Trek’s Project One Ultimate program allows you to work with a designer to come up with a one-of-a-kind finish, and Trek will source any parts you want for your new bike.

Photo credit: courtesy
Photo credit: courtesy

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