Trek Madone SLR 9 AXS Gen 8 Review — Aero Comfort

When Trek announced the all-new Gen 8 Madone as their one-bike-solution, it was a little surprising. After all, the latest Madone was only a year old and the Emonda was still highly-regarded as one of the top climbing bikes. However, after learning more about it and now spending hundreds of miles aboard the 2025 Trek Madone SLR 9 Gen 8, I fully understand why it’s now Trek’s do-it-all race bike. So, if you’re looking for something that’s wicked-fast in the flats, climbs like a mountain goat and remains one of the most comfortable race bikes I’ve ever swung a leg over, you’ll want to double-tap on this one.

2025 Trek Madone SLR 9 AXS Gen 8 Features:

• 900 Series OCLV Carbon
• Aero-optimized Full System Foil tube shapes throughout
• IsoFlow seat tube port
• Electronic-only compatibility with full-internal routing
• Trek Aero RSL integrated bar/stem
• SRAM Red AXS groupset with climbing-friendly gearing (46/33T with 10-33t cassette)
• Dual-sided integrated Quarq power meter
• Bontrager Aeolus RSL 51 wheelset and Aeolus RSL RD 28c tires
• Bontrager Aeolus RSL saddle
• Aerodynamic bottle cages and bottles (accepts regular bottles too)
• T47 threaded bottom bracket
• UDH-compatible frameset
• MSRP: $13,499

Madone SLR 9 Gen 8 – Specs and setup

It’s not always that the top-of-the-line build kit shows up for review, but it’s always incredible when it does. This time it’s the all-new Trek Madone SLR 9 Gen 8 with the latest SRAM Red AXS and a smattering of incredible components hung aboard Trek’s new one-bike-quiver. What’s the cost for this stunner?!? Well… we’ll get there later. Fair warning, you’ll likely want to call Capital One to increase your credit line now.

As mentioned, Trek has now put all their race bike marbles into a single bike and it’s a thing of beauty. The Madone now goes head-to-head with the best from Pinarello, Specialized and Colnago, who all have a single race bike solution. Eliminating analysis paralysis when it comes to bike choices was a top reason for merging the Madone and Emonda, but there’s even more to it.

Using their latest 900 Series OCLV, the Gen 8 SLR frameset is 320 grams lighter than the Gen 7 Madone, which puts it just as light as the Emonda. And, aerodynamics spank the Emonda and are on par with the previous-generation Madone. The geometry is similar to the Gen 7, but switches to letter sizing with the ML being about on par with a 56cm. That’s the size I’m riding.

Outside of the new SRAM Red AXS, this top-shelf build includes their new unified Trek Aero RSL one-piece bar/stem and the stellar Bontrager Aeolus RSL 51 wheelset mounted up with Trek Aeolus RSL RD 28c tires. No part of this spec is unworthy of praise and it all tips the scales at a mere 15.6 lbs.

With my 30-inch saddle height and 2.25″ saddle drop to the bars, I was able to pretty much get my fit on this bike, but it required all the available spacers (30mm). There are downsides to this setup but I was grateful to be able to get comfortable on it.

That Magical Madonut Hole

I know what you’re thinking… how can a one-bike-quiver really be as aero as the previous Madone and as light and responsive as the Emonda? The secret is what I call the Madonut Hole (a.k.a. IsoFlow), but it’s much more than that. The entire bike was re-engineered to push the limits in every aspect. They shaved weight throughout and added stiffness where needed and compliance for those long days on rough pavement. And, of course, aerodynamics, which is where the IsoFlow port comes into play.

To achieve the highest aerodynamics, you do have to use the awkward water bottles, but thankfully regular bottles work with the cages too. I did use the aero bottles for a couple of rides and found them to only be worth the hassle if you’re going all-out. While using them, I did nab a PR on The Dip and 9600 N, but they are really wonky to use. In fact, I found myself under-hydrating just because of how funky they are to use on the bike. The opening is also small and it’s hard to squeeze enough water for regular use. Again, the cages work with regular Trek or Specialized bottles and that’s what I used most of the time.

Without wind tunnel validation, I can’t confirm the watts savings or seconds shaved, but I can quantify how smooth and fast the Gen 8 Madone feels in the saddle. At speed, the entire bike feels stealthy and tangibly palpable just how fast it is. I mean, I’ve ridden a ton of bikes and many aero road bikes and no other bike I’ve ridden has felt as cohesive and planted as the new Madone. It reminds me of the final version of the Specialized Venge from 2019 in many respects (I miss that bike), but even better.

Aerodynamics do come into play at both lower and higher speeds. The frame, integrated cockpit and aerodynamic wheels all work together like a symphony and I set a chorus of near-best times on several segments I’ve ridden many times. Here’s a great example where I matched my 2nd best time from 10 years ago when I was 39 yrs old. Yes, the Gen 8 Madone is addictively-fast and effectively shaved 10 years off my fitness.

Climbing and Descending

I’m lucky to have Utah’s Alpine Loop in my backyard. This beautiful canyon is an iconic alpine climb and descent. I’m getting older and my body doesn’t climb quite as well as it used to, but it’s not the bike that’s holding me back. I rode the previous-generation Emonda on the same roads and there’s nothing holding this 15.6 lb. bike back from garnering the fastest times. The 2024 Orbea Orca overlapped saddle time with the Madone this summer and both bikes are equally superb climbers. If push came to shove as a pure climbing bike, I may chose the Orca, but that’s splitting hairs. At the highest tempos both in or out of the saddle, the Gen 8 Madone feels light and responsive and propels you forward with gusto.

I have appreciated having the 1:1 (33/33) gear option on the steepest climbs in the area — allowing me to increase my cadence and ascend with ease. It is amazing how well the Madone responds and I’ve had a blast on long, rolling climbs and steep, punchy walls. Sometimes, when I feel I’m almost gassed, I look down and wonder if this bike is self-propelled.

In 2022, I heralded the Trek Domane SLR for its filthy descending capabilities. While I still stand by that claim, the 2024 Madone gives it a run for the money and actually bested it by a second on a 5-mile descent down American Fork Canyon for my 4th best time ever (on over 200 attempts). Ahem, there’s a reason why this is the only bike Trek’s WorldTour pros ride now. I have had a hoot snaking down the most sinuous roads in the area — begging for more.

As mentioned, I did have to stack 30cm of spacers to get my fit, so that’s where things get less-than-ideal. If you’re okay sacrificing pinpoint handling then by all means, stack it up. It’s more important for me to save my back from getting grumpy than to have razor-sharp handling response. As ridden, I did experience some degradation to the bike’s handling and it fell short of the best-handling bikes I’ve ridden. I would daresay that would change if my body could adapt to a shorter stack height. It was still an adept handler, but I imagine it will improve as you lower the stack. Handling did remain precise and responsive, but didn’t quite have the killer instinct I would expect.

Comfort Beyond Measure

Oftentimes, race bikes (especially climbing bikes) are known to have a rough ride. The Ari Suncrest is a great example of that — it’s wicked-light and super-responsive, but rough roads take their toll. The new Madone handles that with the IsoFlow’s extended seatpost mast on top of the natural comfort built in elsewhere. From my first ride to the last one, I always came away astounded by just how comfortable this bike is.

All harsh terrain is subdued and the entire package delivers comfort typically found on endurance bikes. And, keep in mind that the stock 28c tires aren’t extremely-wide. Running them at 58/60 PSI has yielded a dream-like ride. Without question, that comfortable ride quality is a team effort with the tires, wheels, frame design and saddle, but it just plain works. For a few rides, I swapped out the wheels for the Forge+Bond CR 45 with the Pirelli P Zero Race TLR RS 30c tires and while the ride felt more muted and traction was a little better, it wasn’t any more comfortable than the stock setup. For reference, that combo measures out to 33mm wide against the relatively-modest 29mm wide with the stock Bontrager wheels/tires.

Truthfully, I appreciated the improved response that the stock setup provides. Don’t sleep on the Bontrager tire/wheelset combo… those hoops roll with the best wheels on the market and add a ton of comfort. At 51mm deep, the Aeolus RSL 51’s are a little deeper than most wheelsets I commonly ride. But, the rim profile is stupid-stable in crosswinds. Looking closely, it’s not a snub design that’s common these days, but is much more pointed. I had zero stability issues riding at the highest speeds while getting bombarded with sudden crosswinds. (BTW… The less-expensive Aeolus PRO 51’s remain some of my favorite wheelsets.)

Final Bits and Pieces

As Trek’s premiere race bike, outfitted in the most drippy kit available, the Trek Madone SLR 9 AXS Gen 8 is one heck of a rush to ride. The entire package is worthy of the astronomical price tag and performs with panache. I really appreciated the built-in dual-purpose computer/light mount and found it perfect for the Wahoo Elemnt ROAM V2 and a Trek Ion 100 front light.

I really fell in love with the Trek Aero RSL cockpit and didn’t miss having fully-wrapped tops one bit. I could always find the right position in the hoods or the drops and even even dabbled with the tops, when needed. I also appreciate that the stem cap is compatible with or without spacers on top and includes a cover for either preference. No other unified cockpit offers that and I appreciate it for both fit flexibility and resale. Not only are the tops more aero than before, the backsweep keeps the tops out of the way of my knees on standing climbs.

And, I can’t say enough good things about the all-new 2024 SRAM Red AXS on this bike. Shifting is even faster and more responsive and those new brake hoods and shifters are a thing of beauty. Notably, the true one-finger braking has me wrapped around my one finger. You can brake with two fingers, but you won’t get any more power or modulation than you will with just one finger. I’ll share a detailed review of the groupset separately, but it is the absolute top-dog in the groupset battle, in my opinion.

Fit: I’m 5’11” and 175 lbs, riding the size ML with the full 30mm of spacers. It’s a moderately-aggressive fit, but has kept my body happy throughout hundreds of miles. I inflated the tires to 58/60 psi throughout all my test miles.

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