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New Trek Madone SLR ditches the decoupler to shed weight and gain speed

Adjustable IsoSpeed turns into structural IsoFlow to help make the new Madone SLR 300g lighter and save the rider up to 19 watts

Sam Challis
30 Jun 2022

The seventh generation Trek Madone SLR has been given an aggressive overhaul to become a claimed 300g lighter and save the rider up to 19 watts at 45kmh compared to the previous Madone SLR.

Trek says it is the fastest bike it has ever made, and tests fastest against all competitors the brand has tested to date.

The new Madone is also one of the most expensive bikes Trek has offered too. The new Madone SLR will be available in six different guises, with prices ranging from £6,850 to £13,800 and the bike is available to order now, with deliveries expected in August. Project One customisation is expected at a later date.

The distinctive IsoFlow feature at the seat tube cluster replaces the IsoSpeed device on the Madone SLR’s predecessor. Trek says that means the bike doesn’t offer as much vertical compliance as the previous bike, but allows for performance gains in stiffness, weight and aerodynamics.

A size 56cm Trek Madone SLR 9 is claimed to 7.1kg, making the new bike one of the lightest in its category.

The Madone’s proprietary cockpit goes back to being one-piece, but achieves a much lighter weight and uses adjusted ergonomics to also contribute to the new bike’s speed improvements by narrowing the rider’s body position.

The new bike is compatible with electronic drivetrains only and Trek officially recommends a 28mm max tyre clearance, although that is with 6mm of space around the whole circumference of the tyre. The new Madone SLR’s geometry is the same ‘H1.5’ fit used in the previous bike.

Trek Madone SLR: 10 things you need to know

  • The fastest bike Trek has ever made
  • 300g lighter than predecessor
  • Up to 19 watts faster as a bike-rider system at 45kmh
  • The adjustable IsoSpeed has been ditched in favour of seat tube hole called IsoFlow
  • Frameset made with Trek’s OCLV 800 carbon composite blend
  • All kamm-tail aero tube profiles have been adjusted, BB shell heightened
  • Cockpit is one-piece, but significantly lighter
  • Cockpit uses narrower hoods and flared, compact drops
  • Prices range from £6,850 to £13,800
  • Order arrival expected in August

Keep it simple, stupid

Thanks to the inclusion of various iterations of the IsoSpeed decoupler system Trek first introduced to the Madone platform in 2015, the brand’s dedicated aero road bike has always been considered among the best in its genre at balancing aerodynamic efficiency with comfort.

Later iterations of the design even had the ability to adjust how much flex the IsoSpeed device could provide, but Trek says that it found for the vast majority of riders, it was a case of set-and-forget on its most compliant setting.

‘What’s more, when we started development on this latest Madone, the feedback we got from our pro riders was that they needed the bike to be faster and lighter,’ says Jordan Roessingh, Trek’s director of road bikes.

As one of the most complex parts on the bike, Trek says the IsoSpeed system was given a lot of attention as it was an area where significant gains could be made given the goals of the redesign.

The Isoflow feature was the end of result of that process. It’s essentially a hole in the seat tube, but Trek says it has been configured to provide a host of benefits for the new frameset.

Most pertinently given the IsoSpeed comfort booster it replaces, Trek says the IsoFlow shape cantilevers the top portion of the seat tube, naturally introducing compliance to the area in a similar manner to IsoSpeed but in a much simpler fashion.

‘The compliance IsoFlow provides is a similar amount of comfort as IsoSpeed did in its stiffest setting,’ says Roessingh.

‘It was a unique design challenge from a composite layup perspective, shaping perspective and even a safety perspective, but we’ve been making them for two years now so are confident in the concept’s durability.’

Multifaceted design

Trek said it needed the refined seat tube cluster to work on levels beyond just comfort in order to satisfy the requests of its pro riders concerning the frameset’s more aggressive performance characteristics.

‘IsoFlow accelerates the air flowing around the head tube and into the low pressure zone behind the rider,’ says Alex Bedinghaus, Trek’s senior design engineer.

Low pressure or energy air creates a lot of drag, as it is essentially pulling on the rider in a similar way to high pressure air pushing on the rider.

‘The hole in the seat tube funnels air into that low pressure area faster, decreasing the drag effect of that low energy zone on the rider,’ says Bedinghaus. ‘IsoFlow creates a 3-watt saving over the design previous bike on its own.’

All the aero

A fully revised set of kamm-tail tube profiles across the rest of the frame, plus bulked up dimensions in areas like the heightened bottom bracket shell, make up the rest of one half of the claimed 19-watt improvement the rider can experience switching to the new bike from the old while keeping the same bar size.

According to Trek this equates to saving 1 minute every hour of riding at 45kmh. 45kmh isn’t a particularly sustainable speed, so interestingly Trek says the new Madone still saves 58 seconds when riding at 25kmh.

‘Bringing up the bottom bracket shell closer to the water bottles reduces the wake they create,’ says Jon Davis, one of Trek’s aerodynamicists. ‘Plus carbon layup scheduling and aerodynamic refinement is such an intensive, iterative process we were able to refine things generally purely by having better technology and a starting point that was further on than when we worked on the previous bike.’

The other half of the new Madone’s claimed advantage is apparently achieved by its one-piece cockpit placing the rider in a more aerodynamic position, ie, narrowing their frontal profile.

‘The bars are 3cm narrower at the hoods than in the drops, so a 42cm bar (measured at the drops) has hoods that are 39cm apart’ says Davis. ‘What’s more, the drop shape is more compact, with a 20mm shorter reach, meaning it should be more comfortable to spend more time down there.

‘We also worked to develop the shape of the cockpit with respect to the rider being downstream in the airflow, which is not something that is often considered. That is a lot of interaction between the flow coming off the bars and the vortices that are created by the rider.’

For those bemoaning the apparent backwards step in adjustability the new one-piece cockpit brings, Trek says it will offer 14 different sizes of cockpit to help riders find the best fit, and the bike can fit a standard bar and stem combo by changing to a different headset top cap.

Lightening up

The 300g of weight loss Trek says it has achieved in the new Madone is significant without even considering the claimed aerodynamic improvements.

The new Madone is markedly cleaner looking than the old one, and Bedinghaus says that the reduction in mass was mostly down to better structural efficiency, ie, simpler shapes.

‘We looked at refining the Madone weight wise as a chassis rather than just the frameset,’ Bedinghaus says. ‘The bar/stem combo being one piece introduced almost half the weight saving and the change to IsoFlow contributed meaningfully too.

‘Then the cleaner tube profiles combined with a more efficient layup schedule and refined smaller details like a new seatpost clamp also helped take weight out.’

That seatpost is available in two lengths and two offsets, so while proprietary should accommodate most riders.

If the rider is concerned about maximising the weight and drag reduction of the frame, Trek has made the front derailleur hanger removable so a 1× drivetrain setup can be used cleanly.

Speaking of extra options, the new Madone’s tyre clearance is notably versatile too. Trek officially recommends that at maximum a 28mm tyre should used, but admits that is with 6mm of space all around the tyre, meaning in reality something like a slick 35mm should fit in the new bike with room to spare.

The new Madone SLR will be available in 6 different guises, with prices ranging from £6,850 to £13,800 and the bike is available to order now, with deliveries expected in August.

Trek Madone SLR range overview

All specs use the same OCLV 800 frameset, seatpost and cockpit. Notably, all SRAM specs include the power meter-equipped version of the respective groupset’s cranksets.

Trek Madone SLR 6

  • Price: £6,850
  • Weight: 7.75kg
  • Groupset: Shimano 105 Di2
  • Wheels: Bontrager Aeolus Pro 51
  • Tyres: Bontrager R3 Hard-Case Lite
  • Saddle: Bontrager Aeolus Elite

Trek Madone SLR 6 eTap

  • Price: £7,450
  • Weight: 8.03kg
  • Groupset: SRAM Rival AXS
  • Wheels: Bontrager Aeolus Pro 51
  • Tyres: Bontrager R3 Hard-Case Lite
  • Saddle: Bontrager Aeolus Elite

Trek Madone SLR 7

  • Price: £9,150
  • Weight: 7.48kg
  • Groupset: Shimano Ultegra Di2
  • Wheels: Bontrager Aeolus Pro 51
  • Tyres: Bontrager R3 Hard-Case Lite
  • Saddle: Bontrager Aeolus Elite

Trek Madone SLR 7 eTap

  • Price: £9,600
  • Weight: 7.76kg
  • Groupset: SRAM Force AXS
  • Wheels: Bontrager Aeolus Pro 51
  • Tyres: Bontrager R3 Hard-Case Lite
  • Saddle: Bontrager Aeolus Elite

Trek Madone SLR 9

  • Price: £12,700
  • Weight: 7.1kg
  • Groupset: Shimano Dura-Ace Di2
  • Wheels: Bontrager Aeolus RSL 51
  • Tyres: Bontrager R4
  • Saddle: Bontrager Aeolus RSL

Trek Madone SLR 9 eTap

  • Price: £13,800
  • Weight: 7.36kg
  • Groupset: SRAM Red eTap AXS
  • Wheels: Bontrager Aeolus RSL 51
  • Tyres: Bontrager R4
  • Saddle: Bontrager Aeolus RSL

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