New Trek Domane endurance bike bins IsoSpeed suspension and down tube storage in favour of weight savings
Fifth-generation bike gets a new frame layup and seatpost, as well as pricing to appease the masses
Trek has removed its IsoSpeed frame-compliance technology and internal frame storage from the fifth-generation Domane endurance road bike to help reduce claimed frameset weight by up to 305g. It says the lightest spec weighs 950g less than before at 6.63kg, albeit with 28c tyres.
A new carbon layup and round seatpost, and wider 40mm tyre clearance mean the new bike is nearly as compliant as before, according to the American brand. Even when fitted with wider 35mm tyres, Trek says the new Domane is faster than its predecessor because lower rolling resistance cancels out higher drag.
Trek has further relaxed the Domane's riding position by adding a riser bar that increases the effective stack by 20mm. It also gains a UDH-compatible rear dropout to enable the use of SRAM's Full Mount derailleurs, which attach directly to the frame. Mounts for mudguards and bags remain.
Complete builds start from $2,400 for the Domane SL 4 (available in the US only), which is cheaper than before, and prices rise to £11,250/ $11,499/ €10,499 for the range-topping Domane SLR models. Trek appears to have discontinued the pro-focused RSL version, which had only been available as a frameset.
The end of IsoSpeed
IsoSpeed was Trek's built-in frame suspension, which, the brand claimed, provided flex to improve comfort. But it has been phasing out the technology over the past two Domane generations to reduce weight and complexity.
At its launch in 2022, the fourth-generation Domane lost IsoSpeed from the front of the headset while retaining IsoSpeed in the top tube. This worked by decoupling the top tube from the seat tube to damp vibrations. Trek removed adjustability from this version of IsoSpeed, claiming riders tended to leave it on the most comfortable setting.
It has now gone a step further in making the new Domane frame fully rigid. Trek says the increases in stock tyre size from 32c to 35c and maximum tyre clearance from 38mm to 40mm combine with greater frame and seatpost compliance to compensate. Using vibrational power as a measure of 'full-bike comfort', the brand says the fifth-generation Domane with 35mm tyres gets within five percent of the old model with IsoSpeed and 32mm tyres.
"I'm not surprised to see the demise of IsoSpeed on Trek's road bikes. While it did work on its mountain bike offerings, particularly the Procaliber hardtail, the trend towards wider tyre volume and lower pressures, and the many benefits this affords, has significantly improved ride quality and overall compliance. It has also allowed Trek to cull some weight and come up lighter than before across the board. It's good to see a maximum tyre clearance of 40mm - this is better than some of its rivals and will likely find favour with those who enjoy stitching in a smidgeon of gravel on their rides."
Weight reduction
Although not mentioned in the launch press material, it's clear from the images of the new bike that it no longer has storage in the down tube, which you accessed by removing a hatch over the bottle cage bosses. Like the removal of IsoSpeed, this appears to be another weight-saving move. Trek will separately sell frame bags, which attach to new mounts in the frame triangle, to mitigate the loss of carrying capacity.
As a result, Trek says the new Domane SLR frame using new 900 Series OCLV carbon weighs 835g in an unpainted ML size, and the fork weighs 367g. That amounts to a claimed 305g reduction in frameset weight. The fully built Domane SLR 9 weighs 7.3kg, according to Trek.
The cheaper Domane SL frame and fork, made from lower-grade 500 Series OCLV carbon, are said to weigh 1055g and 430g respectively, also in size ML without paint. Trek says the Domane SL 5 weighs 8.8kg.
Revamped sizing philosophy
While Trek has maintained the Domane's endurance geometry, it has cut down its size range from nine to six, which is still more than some brands offer.
It's done so by reducing the extremes of reach and stack, which may come as bad news if you're at either end of the size chart, but shouldn't negatively impact most people's bike fit.
Stock crank lengths are shorter across the range at 160mm for sizes XS and S, 165mm for M and ML, and 170mm for L and XL.
The Bontrager Riser bar, which adds 20mm of height to the default shifter position, is back-swept for a more comfortable hand position on the tops and has a 4cm flare.
From Tiagra to Project One
The Domane carbon range starts at $2,400 with the 2x Tiagra-equipped SL 4, which is only available in the US. For comparison, the aluminium Domane SL lineup ranges from £950 to £1,600.
Specced with mechanical Shimano 105, the Domane SL5 costs £2,500/ $2,700/ €2,500 with the same alloy Bontrager rims.
The Domane SL 6 AXS comes with SRAM Rival 2x and Bontrager Aeolus Elite 50 carbon wheels for £3,750/ $4,200/ €4,000. On the same wheels but with SRAM Force 1x XPLR, the Domane SL 7 AXS will set you back £6,300 / $6,500/ €6,999.
In the lighter and more expensive carbon, the Domane SLR 7 is priced at £6,700/ $7,999/ €6,999 with Ultegra Di2 and Bontrager Aeolus Pro 51 wheels. For the equivalent spec with SRAM Force AXS, you'll pay £8,500/ $8,499 / €7,499 for the Domane SLR 7 AXS.
To step up to Shimano Dura-Ace Di2 and Bontrager Aeolus RSL 51 wheels, the Domane SLR 9 will cost you £9,000/ $10,999/ €9,999. The SRAM equivalent is the SLR 9 AXS at £9,000/ $11,499/ €10,499.
The range-topping Domane SLR 9 AXS 1X, which hits that headline 6.6kg claimed weight, costs £11,250/ $11,499/ €10,499 and is equipped with the integrated RSL cockpit from the Madone race bike. It does, however, seem odd to fit 700x28c Pirelli P Zero Race tyres to a bike with 40mm clearance.
Trek will continue to offer its Project One customisation scheme on the Domane SLR. For a price, it lets you personalise components and paint at point of purchase.
It will also sell just 124 of the Project One 'Icon No 76' Domane SLR 9 AXS for $14,999 / €12,999. The original Trek logo and heritage blue paint celebrate the brand's early designs.
