Aero race bikes have always carried a bit of a reputation. They’re fast, no question, but historically they’ve also been stiff, unforgiving, clumsy, and sometimes a little too focused on wind-tunnel bragging rights. The newest Giant Propel Advanced SL aims to shift that perception.
It’s still unapologetically aero, still clearly built for racing, but after spending time on the latest Propel Advanced SL 0 with Shimano Dura-Ace Di2 and the updated CADEX 50 wheelset (reviewed here), it’s clear Giant has pushed this platform into a more refined, real-world race machine.
That doesn’t mean it’s suddenly a plush endurance bike. Far from it. The Propel is still a top-tier aero race bike built for speed above all else. But compared to the previous generation, the ride quality and handling feel noticeably more balanced—without sacrificing the aggressive performance that made the Propel such a staple in the pro peloton.
And honestly, that’s exactly what you want from a bike like this.
If you want to read all the in/outs of the Gen 4 Giant Propel design, check out our news piece here.
A Bike That Wants to Go Fast
From the moment you roll out, the Propel makes an impression. This bike is built to carry speed, but it’s light like a climbing bike…
The updated frame, integrated cockpit, and the latest CADEX 50 wheelset work together to create a bike that feels incredibly efficient both getting up to speed and maintaining it. There’s very little sense of wasted energy. Every pedal stroke seems to translate directly into forward momentum.
What stood out most on the flats wasn’t just the speed, but how easy it felt to hold it. Once you’re cruising north of 20 mph, the bike settles into a rhythm where maintaining speed feels effortless. It’s the kind of sensation aero bikes are designed to deliver, but the Propel manages to do it in a way that feels stable and predictable rather than twitchy or overly aggressive.
Climbing: Surprisingly Light for an Aero Bike
Aero bikes have gotten lighter over the years, and the new Propel blows that out of the water. Our test medium Propel SL weighs 14.89 lbs, with bottle cages but no pedals. That’s bonkers light for an aero bike.
Point the bike uphill, and it immediately feels more nimble than you might expect from a deep-section aero machine. The Advanced SL frame is impressively light, and that shows when the gradient kicks up. Out-of-the-saddle efforts feel crisp and responsive, with none of the sluggishness that older aero bikes sometimes exhibited when the road tilted upward.
Instead, it sits comfortably in that modern aero-all-rounder category, a bike that climbs efficiently enough that you never feel like you’re dragging excess weight up the hill.
Descending: Stable and Confident
If there’s one area where the Propel really impressed me, it was descending.
Aero bikes sometimes have a reputation for being a little nervous at speed, especially when paired with deeper wheels. The Propel, even with the CADEX 50s, felt incredibly planted on fast descents.
Point it downhill, and the bike tracks exactly where you want it to go. There’s a reassuring sense of stability when speeds start creeping past 40 mph, and the front end remains composed even through long sweeping corners.
Even in the unfamiliar territory of our testing loops, I felt confident sending the machine into corners with the same speed I would race my personal bike. It’s the kind of handling that gives you the confidence to stay off the brakes and let the bike run. Plus, the front end is responsive, so much so that when you make a correction, it’s an instant move, not twitchy but assertive.
Sprinting and Cornering: That Stiff Front End
When the road flattens out, and it’s time to sprint, the Propel comes alive.
The front-end stiffness is immediately noticeable when you stand up and throw the bike side-to-side. There’s zero hesitation in the response. The integrated cockpit and the Advanced SL frame create a front triangle that feels incredibly solid under hard acceleration. Plus, when you factor in the lack of additional weight, you don’t have much to get up to speed.
The same stiffness translates directly into cornering performance.
When pushing the bike into corners at speed, the front end holds its line with precision. There’s none of that vague or flexy feeling that can sometimes creep into bikes with highly integrated cockpits. Instead, the steering feels direct and confident, encouraging you to lean the bike harder and carry more speed through turns.
It’s the kind of handling that racers will appreciate immediately.
Ride Quality: Still Firm, But Noticeably Better
Now, let’s talk about ride quality.
The Propel is still a performance-focused aero race bike, and that means the ride isn’t exactly plush. Rough pavement still makes itself known, and this isn’t the bike you’d pick if comfort were your top (or only) priority.
But compared to the previous generation Propel, the difference is noticeable.
There’s a bit more compliance built into the frame and cockpit, which takes the edge off the harshness that older aero bikes were known for. It’s not night-and-day, but it’s enough that long rides feel less punishing than they used to. Factor in the larger tire accommodations, and you have a very capable and comfortable machine.
For a bike designed primarily for speed and racing, that’s a welcome improvement.
The CADEX 50 WheelSystem
A big part of the bike’s overall performance comes from the updated CADEX 50 wheels.
These wheels feel incredibly well-balanced. At 50mm deep, they deliver the aerodynamic benefits you’d expect, but they avoid the overly sail-like sensation that deeper wheels can sometimes create in crosswinds.
They spin up quickly, hold speed well, and complement the bike’s handling characteristics perfectly.
In short, they feel like the right wheels for this bike—fast, stable, and responsive.
The Drawbacks
No bike is perfect, and the Propel has a few considerations.
The first, obviously, is the price, our test bike is well past the point of being attainable for most at the $13,000 mark
The Propel Advanced SL 0 sits firmly in the “top of the top” category. Between the Advanced SL frame, Shimano Dura-Ace Di2 drivetrain, and CADEX components, this is a serious investment.
The other potential sticking point is the integrated seat mast.
Seat masts have their fans, but they also have their critics. Some riders simply don’t like the idea of cutting a frame to fit. It can make travel a little more complicated, and it may affect resale value down the road.
That said, Giant does provide a bit of flexibility. There’s roughly 25mm of adjustment available through the seat mast topper, which offers some room for fine-tuning the fit. And if you end up purchasing a bike with a slightly shorter mast cut, or trim it a little too short yourself, you still have some adjustment range to work with.
In practice, it’s a manageable tradeoff for the weight savings, compliance, and aerodynamic advantages the system provides.
Final Thoughts
After spending time on the new Propel Advanced SL, it’s clear Giant has refined an already fast platform into something even more capable.
The bike climbs way better than you’d expect, descends with confidence, and delivers impressive stiffness when sprinting or pushing hard through corners. At the same time, the ride quality has improved enough to make it more livable than the previous generation.
Yes, the price is steep. And the seat mast won’t be everyone’s favorite design choice.
But those are relatively small tradeoffs for a bike that sits squarely at the top of Giant’s performance lineup, and might be the best aero bike I’ve ridden to date.
