Trek officially launches new Madone with Isoflow seat tube

The seventh-generation Madone is lighter, faster, still kind of comfy, and has always-available DRS.

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Since switching its Madone from a lightweight climbing bike to an aero-focused speed machine in 2012, Trek has described the platform as the “ultimate race bike”. First, with Kammtail tubing, then deeper tubes (and the deepest decals), upside-down brake callipers, and flappy paddle brake covers, the Madone designers have focused on maximising aerodynamics and speed within the UCI regulations. Compliance was also high on the agenda, so Trek incorporated its IsoSpeed decoupler into the Madone top tube.

But all that aero and comfort came with a cost as the Madone bikes piled on the grams over the past decade.

Now Trek has a new Madone and while aero and compliance are still major targets, reduced weight was a must-have. Something had to give, and seemingly that something was a hefty chunk of the seat tube. The new Trek is an entirely new design with some lofty claims, but it’s still recognisably a Madone.

While we haven’t yet had a chance to ride the new bike, here’s what we know so far following a one-on-one meeting with the Madone design team.

In keeping with what is almost Trek tradition at this point, the new bike first appeared at the Criterium du Dauphine earlier this month. The Dauphine offers a chance for the pros to race-test the new rig before the big bike race around France throughout July.

However, that pro testing on the new Madone stretches right back to before the previous Madone was even announced. Trek relies on its WorldTour teams for feedback on current platforms in developing new models, and those pros told Trek the next Madone had to be lighter. Presumably more aero and stiffer also, but mostly lighter. Definitely lighter.

As such, weight reduction was one of Trek’s biggest design goals for the new seventh-generation Madone and the obvious place to start was with the IsoSpeed decoupler. Trek’s solution to bringing a smoother ride to an aero frame did an admirable job of taming rough surfaces and creating an aero bike that rode somewhat like a conventional bike, but it came with a weight penalty.

Mads Pedersen’s new Trek Madone SLR

This extra bulk jarred the minds of the pros who are seemingly happy to trade mind-jarring for bone-jarring if the result is a lighter, faster bike. Put simply, and as is often the case, the pros were not totally convinced they needed a smoother ride, but were passionate about having a lighter bike.

IsoSpeed simply had to go. The new Madone ditches the pivot and flexing components of IsoSpeed and instead gets a big hole in the seat tube, a host of aero tweaks, new tube profiles, and an entirely new cockpit. All told Trek claims the new seventh-gen Madone is 300 grams lighter and 19 watts (or 60 seconds per hour) faster than the outgoing Madone, all while retaining some level of comfort.

Is it a hole? Is it a wing? It’s IsoFlow!

So IsoSpeed is gone, and into its place steps IsoFlow nothing, just a great big hole. Unsurprisingly with such a unique design element all talk about the new Madone has focused on this seat tube gap, but what exactly does it do? Well, at least according to Trek, IsoFlow does a bit of everything: it offers aero gains, weight savings, and similar ride-smoothing benefits as the outgoing IsoSpeed (in its stiffest setting).

We recently sat in on the media launch for the new Madone and followed that up with a desk-side Q&A with Trek’s road bike heads of design and aerodynamics. In both meetings, we were told how central IsoFlow is in achieving all the parameters and goals Trek set for the new Madone. Although the feature first emerged as an aero tweak, it offers the added benefit of added compliance and reduced weight.

IsoFlow – DRS for all

IsoFlow is said to be the result of a considerable amount of aero testing, wind tunnel testing, CFD and computer modelling, all looking at which areas of the frame offered the greatest drag savings. CFD, in particular, allowed Trek to extrapolate the benefits of each design tweak in ways a wind tunnel simply can’t replicate.

While Trek looked at the front end of the bike and has made changes there also, the American brand seemingly decided the seat tube area offered the greatest potential and of all the concepts it investigated – including variations of IsoFlow, dropped stays, steeper and slacker stays, bigger and smaller holes – the final IsoFlow offered the greatest drag reduction in a functional design permitted within the UCI regulations.

Aerodynamicist John Davis explained Trek initially hadn’t considered the weight and compliance benefits of IsoFlow. The brand was merely incorporating the feature having considered all other updates to the seat tube and seat stay before ultimately settling on the split tube design due to its drag reduction benefits.

The IsoFlow design handily integrates a number 7 into the 7th generation frame.

Davis explained that the IsoFlow hole is designed to accelerate air from around the head tube and direct a jet of fast-moving air or high-energy flow into a low-energy area behind the bike and rider. Getting rid of this low energy in high drag areas is said to improve the aerodynamics of the entire system.

F1 fans can think of IsoFlow as an always-available DRS (Drag Reduction System). Aero drag drops when the driver opens that rear wing flap on an F1 car. Trek is seemingly leaning on a similar concept here, opening up a chunk of the seat post to reduce drag and improve aerodynamics. When asked, though, if the turbulent or so-called dirty air coming off the rider’s legs disrupts any aero gains in this area, Davis explained that while they can’t make subtle tweaks to guide the turbulent flow, it can direct bulk movements of airflow and effectively feed the IsoFlow.

Faster and lighter

All the aero claims sound good, but remember weight reduction was Trek’s main target for the new Madone. Well, as luck would have it, apparently removing the heavier IsoSpeed system and a large chunk of seat post also works wonders for reducing frame weight.

Well, sort of. Delving into the numbers Trek has provided suggests less than half of that 300 g weight saving comes from the frame, with the new bar stem providing the greater proportion of the savings, but more on this later. Still, the aero and weight savings come as a package, with the claimed IsoFlow aero savings not possible without dropping the IsoSpeed, while simply removing IsoSpeed without any aero improvement or new compliance features would likely result in a significantly less good Madone.

Compliance

The challenge for Trek was how to drop weight and retain that “conventional bike” ride feel. IsoSpeed may have added considerable weight to a frame, but it had countless fans and did an admirable job of taming rougher surfaces on an otherwise performance-focused bike.

Trek, and most paying customers, probably still care for some ride comfort even if the pros do not. Furthermore, comfort, although tough to quantify, does play a definite role in overall performance. With the removal of IsoSpeed, Trek had to find a new way to add ride compliance back into the new Madone. Again, as luck would have it, compliance is the final part of the IsoFlow hat-trick.

While the hole in the seat tube rightly draws much of the attention, the other part of the IsoFlow concept is the cantilevered seat mast. Trek claims this works with the new wider and shallower top tube featuring a thinner cross-section allowing the seat post member to flex and add back some of the compliance removed with the disappearance of IsoSpeed.

The cantilevered seat tube and wider and thinner top tube are said to combine to add back some of compliance lost through the removal of the old IsoSpeed decoupler.

The Trek presentations described how IsoFlow offers a simpler and lighter way of introducing ride compliance – the cantilevered seat post flexes over bumps and provides a smoother ride – while retaining stiffness for out-of-the-saddle sprints. In fact, Trek suggests the IsoFlow offers similar comfort levels to the outgoing IsoSpeed’s stiffest setting.

Perhaps unsurprisingly Trek also suggests that while IsoSpeed’s softer settings were great over cobbles and very rough terrain, its Domane may be the better bike for those conditions. As such a stiffer Madone is more in line with how the bike is most often raced.

Simpler it may be – without the pivots, adjustability, and flexing components of the IsoSpeed system – but IsoFlow seems far from simple to design. I put it to Trek that the new IsoFlow design seems to introduce the opportunity for significant stress points in a cantilevered seat post with such sharp angles. I gave the example of hitting the first cobble of the Forest of Arenberg at 65 km/h with the rider’s weight fully back in the saddle.

Alex Bedinghaus, Trek’s senior design engineer, agreed Trek certainly could have made life easier for themselves than deciding to, as he describes it, “create something entirely new, in carbon, with multiple junctions, while making the system aerodynamic, lightweight, and manufacturable.”

All up, the designers spent somewhere in the region of four to five months of development time solely on IsoFlow and ensuring the design was capable of withstanding the forces exerted on those potential stress points. The designers worked through various iterations to find the optimal pedalling stiffness and vertical compliance while still being structurally sound to cope with ultimate loads in a high-stress area.

My non-engineer brain sees the answer to this problem as simply adding more and more layers of carbon into that high-stress area to ensure the suspended seatpost doesn’t fail on the first cobble at Arenberg. Such a solution also carries the obvious knock-on effect of compromising the compliance the IsoFlow design might offer, and Bedinghaus explains it’s not quite so simple.

Simply adding more and more carbon would increase the stiffness too far, diverting flex to other areas of the frame and actually increasing the risk of breakages in a rigid and high-stress area. Instead, Trek claims to have optimised the material choices in this area with varying carbon thicknesses and laminates used throughout the top tube and through the seat mast, balancing stiffness and energy absorption where required.

With all these challenges why didn’t Trek just drop the stays and opt for a narrower seat tube? After all, that’s a design we have seen on countless frames by now. Trek claims simply dropping the stays isn’t always as effective as it may appear and introduces new design challenges in maintaining ride quality and maintaining the compliance offered by either of its Iso systems.

Particularly, Trek suggests dropped stays would have forced it to move to a much narrower seat tube, significantly altering the aerodynamic gains from the entire bike. Simply put, Trek says IsoFlow allows it to hit all the design parameters achieving the vertical compliance and gains it had set out for the new Madone.

All-new frame

The new IsoFlow will no doubt be the centre of attention when the new Madone lands on shop floors and local roads, but Trek has made a host of other updates to the Madone platform. Unsurprisingly, Trek is claiming its new Madone – its flagship, aero-focused speed-motivated platform – is its fastest road bike ever.

The design team was tasked with retaining the overall aesthetic and identity of the Madone while starting with a blank slate to design an entirely new frame. Perhaps most notably, but also the most subtle update, is a new generation of Kammtail tube shapes, which Trek says are derived from thousands of iterations found from improved computing power and software its designers now have access to on-site. The new Kammtail shapes feature blunter noses and rounder trailing edges.

Aerodynamicist John Davis goes so far as to suggest the new Kammtail tubing is a significant development that would otherwise have been Trek’s major talking point in a new frame had they not developed IsoFlow.

These new Kammtail shapes and an ever-improving understanding of carbon layups are said to combine with Trek’s OCLV 800 carbon fibre, to create a more aerodynamic and also lighter frame throughout.

These updates include a smoother head tube with the old headset cut out making way for an integrated design, a down tube said to be aero-optimised for use with and without bottles, and a taller bottom bracket shelf for improved flow over the rear of the bike.

Trek also optimised what remains of the seat tube for both aero and weight savings and introduced a removable front derailleur mount for improved aerodynamics with 1x setups. Just about the only thing remaining from the previous-generation Madone is the T47 bottom bracket.

The bottom bracket has now grown taller than this 56 tooth chainring

Rounding out Trek’s aero claims for the new Madone, the brand suggests that around half the aero savings of the new platform are from the new Madone chassis with the other half coming from the improved rider position the new cockpit enables (more on this in a moment). Within the aero savings from the chassis, around a third come from the IsoFlow design, while all the minor details and aero tweaks to the frame combine to make up the other two-thirds. Again these are calculations made possible by CFD modelling which allows the aerodynamicists to isolate separate design interventions and measure their effectiveness.

Weight-wise, the new frame (as mentioned above) accounts for just less than half of the weight savings across the entire bike. Dropping the IsoSpeed sheds some weight, although it is difficult to extrapolate the exact difference due to a host of other adaptions and factors required to accommodate both designs.

Trek also found some weight saving in a new seatpost clamp designed specifically for the new Madone. Combined with the new seatpost, this new clamp offers a greater saddle height range with lower and higher saddle heights both now possible with each seatpost option.

All told, Trek is describing the new rig as its lightest-ever disc brake Madone, although, given the weight of the previous disc Madones, that’s not exactly earth-shattering news.

Perhaps unsurprisingly the new Madone is only compatible with electronic groupsets, be they wired or wireless. Riders choosing a Shimano build will still find their internal battery hidden inside the seat tube. Although, sitting as it now does below the IsoFlow opening, the battery is only accessible by removing the bottom bracket.

Maximum tyre clearance is officially set at 28 mm, but Trek was at pains to point out this figure still offers 6 mm clearance all around and so riders may want to experiment with wider rubber.

All-new cockpit

Along with the frame, Trek has completely redesigned the cockpit, introducing a new one-piece bar stem optimised for both weight and aero. In fact, at approximately 160 g lighter than the previous cockpit design (depending on the size), just over half the weight savings of the entire Madone chassis were realised in the newly designed stem.

The new handlebars are not just lighter though; the design team has overhauled what we might expect from a stock road handlebar. Most notably the new bars feature 3 cm of flare in the drops. With the bar sizes measured in the drops, this flare puts the lever hoods 3 cm narrower for the same size bar, a move Trek says allows riders to adopt a much more aerodynamic riding position.

There’s fully internal hose and wire routing through the new stem which features a sleeker interface with the redesigned spacers, headset, and top tube.

Just as with the weight saving, Trek suggests just over half of the total drag savings from the new bike were realised through the new narrower hand position the new cockpit enables. It’s not the first time we have heard of the aerodynamic benefits of different hand and arm positions and it’s in keeping with the trend toward narrower setups, particularly since the UCI outlawed the ‘puppy paws’ position.

While the suggested savings might have their fans and detractors, much like with the retained focus on ride comfort, Trek’s focus on not just improving frame aerodynamics but also rider aerodynamics seems like a smart move. The rider on top of the bike will always create the vast majority of the total system drag, so anything that helps riders adopt a more aero position and reduce that drag will almost always have a greater benefit than any adaption to the frame.

The new bars are not just fast because they are narrower. Trek also incorporated its new Kammtail tube shapes into the tops of the bars, again focusing on the wake behind the tube rather than just the tube itself. As such, Trek believes it can move to a more ergonomic bar shape and still reduce drag due to how the airflow interacts with the rider’s legs.

Trek suggests traditional aero-profiled handlebar tops which appear really fast in wind tunnel testing actually increase the airspeed hitting the rider’s legs, potentially neutralising the benefit of the aero handlebars. Trek designers focused on improving the flow interaction with the rider, allowing the designs to incorporate a more ergonomically shaped bar top without increasing aero drag.

The new bar tops look like the kind of size and shape a hand can actually grip around. The backward sweep is said to help put wrists in a more natural position.

The new bars certainly look much more ergonomic than large wing-profiled handlebar tops. The new bar top’s circumference is similar to that of a 31.8 mm round bar, meaning the grip surface area, while still aero profiled, should feel much closer to the grip you might expect from a round bar. Coupled with a significant backsweep and downsweep, Trek claims the new bars allow for much more natural wrist positions and, ultimately, improved comfort.

The drops are new also. There is of course that 3 cm of flare, which Trek says provides a stable and strong platform for sprinting and cornering. The new drops also feature shorter reach and a new curvature designed to enable riders to spend more time in the drops.

The stem is also designed for improved aerodynamics, blending with the bars and flowing into the headset spacers and new top cap in a design which also looks much sleeker.

The new bar stem design is available in 14 different sizes and Trek suggests maintaining your traditional bar width of choice, which will result in your levers sitting 3 cm narrower. If you are not convinced or would prefer to use a different handlebar and stem combo, the new Madone is compatible with standard round 1 1/8” stems. However, a separate bearing top cap from Trek is required.

End result

Trek is making some big aero claims with the new Madone: 19 W faster overall, 60 seconds faster per hour at 45 km/h – essentially you could now ride the same distance in 59 minutes you would have previously covered in 60 minutes.

The savings claims are huge, especially when viewed as a single package. The suggested aero gains are more palatable when assessed on an individual basis. Of the 19 W apparently saved in total, Trek explains more than half of those – 9.7 W – are found in the new rider position and those narrower lever hoods. Again, this makes sense based on what we have seen previously on the importance of hand position and the rider’s contribution to overall drag. Although, we have asked Trek to clarify which position this 9.7 W saving is in comparison to.

The remainder of the savings are said to come from all the marginal improvements made throughout the entire platform. The new Kammtail tubing, the aero bar tops, new head tube, taller bottom bracket etc. all account for about 2/3 of the savings while IsoFlow is thought to account for the remaining third.

Still, almost 10 W is still a huge saving and Trek has reduced the weight by 300 g while retaining some level of compliance. It’s big stuff and it’s a bike we are looking forward to testing in the coming weeks. In the meantime, we will have to both take Trek’s claims at face value, and reserve judgement.

Geometry

Unsurprisingly, Trek has retained the H1.5 geometry first introduced with the previous generation Madone and later on the current Emonda. The H1.5 geometry is halfway between the super aggressive H1 geometry and the more upright H2 fit Trek has offered previously.

What will have changed though is the lever reach for those who follow Trek’s advice and opt for the new 3 cm narrower lever position on the new integrated cockpit. Trek suggests the difference wasn’t great enough to adjust stock stem lengths. Nevertheless, Trek did tell us “riders will have the option to configure their preferred bar width and stem length in Project One once Madone launches within the configurator at a later date. While riders can work with their local dealer to order the appropriate size for bikes purchased off the shop floor.”

All 47-54 cm bikes will get a short seatpost as standard, while bikes sized 56-62 get a tall seat post. All stock seat posts are 0 mm offset.

Model specs, availability and pricing

Trek will offer the new Madone in six models with a range of groupset options and exclusively at its top-end SLR frame construction. Prices start at US$7,999.99 for the SLR 6 105 Di2 bike and go all the way up to an eye-watering US$13,199.99 for the SRAM Red eTap AXS equipped SLR 9 eTap build. The frameset module (including the frame, fork, and seat post) is priced at US$4,599.99 with international pricing TBC.

Every bike across the range is equipped with Bontrager Aeolus Pro 51 tubeless-ready wheels and the new aero bar stem as standard.

As mentioned above, the new Madone will be available through its custom Project One configurator at a later date.

As for availability, officially Trek says it doesn’t expect to have significant inventory at every Trek dealer globally for the first few weeks. The new Madone is available to order through local dealers with first orders delivered within the first two months after today’s launch. Reading between the lines, that sounds a lot like “limited availability at first”.

Also worth noting, Trek will retain the current Madone – including the IsoSpeed – as the Madone SL going forward. It’s due to sit at a lower price point and entry into the Madone range.

More information can be found at www.trekbikes.com.

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