The new Trek Madone SLR is lighter and faster thanks to a big hole in its seat tube

Trek has announced the latest iteration of the Madone SLR, the brand’s flagship aero road bike, which was first spotted at the 2022 Critérium du Dauphiné.

Though the new Madone SLR retains a similar side-profile to the highly rated previous version, it is said to be “the lightest and fastest Madone Disc ever”.

In total, this seventh-generation Madone SLR is claimed to be 300g lighter and “60 seconds faster per hour” than the outgoing model.

Trek attributes this to a set of redesigned tube shapes, a radical reimagining of the seat tube and top tube juncture, and a new integrated handlebar, which is said to promote a “more aero riding position”.

IsoFlow

The 2023 Trek Madone SLR is claimed to be the "lightest and fastest Madone Disc ever". - Trek

The kite-shaped hole in the seat tube, which Trek calls ‘IsoFlow’, replaces the IsoSpeed ‘decoupler’ system. This had been present on the platform since it went all in on aero with the Madone 9 Series in 2015.

Trek claims IsoFlow allows the new Madone SLR to match the compliance of the previous IsoSpeed system on its stiffest setting. It is also said to improve the aerodynamic performance of the frame by “around 3 watts” and save weight.

The IsoFlow system is claimed to improve aerodynamic performance and save weight. - Trek

IsoFlow is claimed to improve the aerodynamic performance of the frame due to an acceleration of airflow through the hole as you ride. This is said to reduce the effect of the trailing low pressure zone behind the bike and rider, reducing your overall drag.

This change was said to be a result of feedback from its sponsored professional riders, such as Mads Pedersen and Ellen Van Dijk of WorldTour team, Trek-Segafredo, who simply requested the new Madone be “faster and lighter, as always”.

IsoFlow is said to accelerate airflow through the hole and reduce the effect of the low pressure wake behind the rider. - Trek

While IsoFlow lacks the adjustability of the IsoSpeed system, Trek says most riders treat IsoSpeed as a ‘set and forget’ system – setting it to a level of desired compliance and then leaving it that way.

Trek also acknowledged its pro riders questioned the performance benefits of the system, and whether those outweighed any added weight and complexity.

Naturally, Trek believes IsoFlow combines the best of all possible worlds, being lighter and more aerodynamic than IsoSpeed, but not compromising on comfort.

IsoFlow is claimed to offer the same comfort as the previous IsoSpeed decoupler on its stiffest setting. - Trek

Lighter and faster than ever

“Overall, the new Madone SLR is around 60 seconds per hour faster, including the rider,” says John Davies, an aerodynamicist at Trek.

“A ride that would previously have taken you an hour, will now only take you 59 minutes.”

In wattage terms, Davies says the new Madone SLR and its rider are claimed to be 19 watts more aerodynamically efficient at 45kph.

Trek says the new Madone SLR will save a rider 60 seconds per hour. - Trek

Davies stresses, though, “you get those gains no matter how fast you’re riding.” Even at 35kph, Davies claims you’ll still see a 59-second improvement, and at 25kph the improvement is calculated to be 58 seconds.

The new Madone SLR is also claimed to be 300g lighter for a complete bike.

In terms of frameset weights, Jordan Roessingh, Trek’s director of road bikes, says the new Madone SLR is “just shy of 1000g for the frame and just over 400g for the fork”.

That translates into complete bike weights from 7.1kg, for a size 54cm bike built with Shimano Dura-Ace Di2 R9270, or 7.4kg for a 56cm bike with SRAM Red eTap AXS.

Trek claims to have cut 300g from the weight of complete bikes. - Trek

While the Emonda SLR is still Trek’s lightest road bike platform by around 400g, Roessingh says, “from our perspective, Madone is almost always the fastest bike for any type of race situation, independent of terrain.”

This is because “the aerodynamic benefit [of the Madone] is dramatic”, and almost always enough to overcome the difference in mass.

Trek says it was able to make such substantial improvements thanks to three changes; updated truncated aerofoil (or ‘Kammtail virtual foils’, as Trek calls them) tube profiles, the IsoFlow technology mentioned earlier and a new integrated handlebar system.

Narrow handlebars are now mainstream

The new integrated handlebar is said to be a key component for both weight and aero improvements. - Trek

The new handlebar is claimed to be responsible for around half of the weight and watts saved.

Trek says 150g and 9.3 watts of aero drag are saved by the updated frame tubes and IsoFlow, while the rest comes from weight savings at the cockpit and improvements to “rider positioning”, as a result of the new handlebar geometry.

Trek says it has cut 150g from the Madone SLR front end by moving to a fully integrated system and a general slimming down of its tube profiles, but the primary driver behind the claimed aero improvement is a narrowing of the handlebar by 3cm at the brake hoods position.

The hoods position has been narrowed by 3cm, which Trek says helps put the rider in a more aerodynamic position on the bike. - Trek

A 42cm Madone integrated handlebar is now 39cm wide measured centre to centre at the brake hoods position, and 42cm wide when measured centre to centre at the drops.

Narrow handlebars are a trend we’ve seen being adopted more frequently at the pointy end of the sport, as riders search for a competitive edge, so it's no surprise to see a major brand has taken notice.

Having a flared bar, with a wider hand position at the drops and a narrower position at the brake hoods, can offer an aerodynamically efficient position up top for cruising on the flat, alongside greater leverage and control on the drops for sprinting and descending.

The drops flare back out by 3cm (1.5cm flare per side) for a wider position. - Trek

2023 Trek Madone SLR geometry

Trek has simplified its fit system for the new Madone SLR, adopting the same H1.5 geometry as seen on the 2021 Emonda.

H1.5 sits “halfway between the previous H1 and H2 fits”, Trek says, meaning it’s essentially a compromise between the super-aggressive, long and low, ‘pro’ H1 fit and the more relaxed, H2 fit.

There are eight sizes in the Madone SLR range, from 47 to 62cm. The new integrated handlebar is available in 11 sizes, with stem lengths from 80 to 120mm and handlebar widths from 38cm to 44cm (not every stem length and handlebar width combination is available, though).

Trek has adopted the H1.5 fit system for the new Madone SLR, bringing its geometry in line with the latest Emonda SLR. - Trek

In addition to narrowing the brake hoods position of the new handlebar, Trek says it has also reduced the reach by 20mm (to 80mm) compared to the previous Madone SLR handlebar.

This brings it more in line with road handlebars from other brands, which typically offer around 60 to 80mm of reach.

Trek also says it’s possible to swap the integrated bar out for a standard 1-1/8in stem, which would enable a rider to use almost any combination of stem and handlebar they like.

Frame size (cm)	47	50	52	54	56	58	60	62
Seat tube (cm)	42.4	45.3	48.3	49.6	52.5	55.3	57.3	59.3
Seat tube angle (degrees)	74.6	74.6	74.2	73.7	73.3	73	72.8	72.5
Head tube (cm)	10	11.1	12.1	13.1	15.1	17.1	19.1	21.1
Head tube angle (degrees)	72.1	72.1	72.8	73	73.5	73.8	73.9	73.9
Effective top tube (cm)	51.2	52.1	53.4	54.3	55.9	57.4	58.6	59.8
Bottom bracket drop (cm)	7.2	7.2	7.2	7	7	6.8	6.8	6.8
Chainstay length (cm)	41	41	41	41	41	41.1	41.1	41.2
Fork offset (cm)	4.5	4.5	4.5	4.5	4	4	4	4
Trail (cm)	6.8	6.2	5.8	5.6	5.8	5.7	5.6	5.6
Wheelbase (cm)	97.2	97.4	97.7	98.1	98.3	99.2	100.1	101
Standover height (cm)	69.2	71.1	73.2	74.4	76.8	79.3	81.1	82.9
Reach (cm)	37.3	37.8	38.3	38.6	39.1	39.6	39.9	40.3
Stack (cm)	50.7	52.1	53.3	54.1	56.3	58.1	60.1	62
Stem length (mm)	80	90	90	90	100	100	110	110
Saddle rail height minimum (w/short mast, cm)	55	58	61	63.5	66.5	68.5	70.5	73
Saddle rail height maximum (w/short mast, cm)	62	65	68	70.5	73	75.5	77.5	80.5
Saddle rail height minimum (w/tall mast, cm)	58.5	61.5	64.5	67	70	72	74	76.5
Saddle rail height maximum (w/tall mast, cm)	65.5	68.5	71.5	74	76.5	79	81	84

2023 Trek Madone SLR build specs, pricing and availability

The 2023 Trek Madone SLR is available to pre-order now in six different builds (with five paintjob options for each build), all with Shimano or SRAM electronic groupsets.

Prices for complete builds start at £6,850 / €7,699 / $7,999.99 / AU$11,399.99, for the Madone SLR 6 and rise to £13,800 / €14,999 / $13,199.99 / AU$17,999.99, for the Madone SLR 9 eTap.

Framesets will be available to purchase separately, but Trek has not yet confirmed how much they will cost.

As things stand, delivery dates for pre-ordered bikes are unclear, as Trek says “supply chain remains a significant challenge”.

The 2023 Trek Madone SLR is only compatible with electronic groupsets. - Trek

The new Madone SLR is no longer compatible with mechanical groupsets, but Trek is continuing with its use of a threaded T47 bottom bracket.

All builds come with Bontrager Aeolus wheels and Bontrager clincher tyres. Stock bikes will ship with 700 x 25c tyres, with the Madone SLR officially having clearance for tyres up to 700 x 28c (although Trek suggests that, unofficially, there’s room for a bit more).

Trek says the existing Madone SL Disc will remain in its catalogue for the time being, offering a cheaper entry point to the Madone range.