The original 2012 Domane revolutionised endurance road bikes, but its innovative bump-eating rear end wasn’t matched by the IsoSpeed fork. Trek’s answer to this imbalance is IsoSpeed within the head tube.
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The new front decoupler has a rocker cup fixed to each side of the head tube by individual pivots, with the upper headset bearing on top. The steerer tube rotates as normal, but can flex fore and aft independently, with no lateral movement.
Trek has redesigned the rear IsoSpeed decoupler system and made it user-adjustable. Instead of a freely-flexing seat-tube, only attached above the bottom bracket by a pivot, this one’s moulded to the top tube. The upper two thirds of it is concave, with a separate seat mast completing its profile, this is pierced by the decoupler pivot below the top tube.
The narrow slot between frame and mast contains a U-shaped plastic slider. Loosening the fixing bolt allows the slider to be moved, altering the mast’s compliance, with more flex at its lowest point, and less at its highest.
Think of it as a plastic ruler suspended over the edge of a table. Twanging a greater length of ruler means greater oscillation, but pull more on to the table, and the oscillations are limited. It needs no specialist maintenance, and there is no weight penalty — Trek’s 600 series carbon fibre, excellent construction and components bring my 56cm example in at an impressive 6.71kg.
When it comes to travelling quickly, the Domane SLR is as effective as any road bike available. Its wide BB90 bottom bracket allows for a huge down tube and solid chainstays, and the oversized IsoSpeed head tube area provides massive front end rigidity. The cumulative effects of the inbuilt compliance delay the onset of muscle fatigue, saving you from tiring vibrations and letting you enjoy riding for longer.
Bontrager’s 28mm R3 tyres on Aeolus 3 carbon rims have a large air volume and generous contact patch. Incredible frame compliance plus big tyres maximise surface contact, increasing cornering grip, steering and braking accuracy, rider confidence and consequently speed.
The Trek uses Bontrager’s compact direct-mount Speed Stop brake calipers with Bontrager-badged Swiss Stop Black Prince pads. Tension adjustment is okay, but not that precise, and it’s possible for the free cable beyond the clamp to rub the tyre unless carefully positioned. But they work effectively, with decent feel and power.
With clean lines, intuitive shifting and minimal maintenance, SRAM eTap’s compact gearing matches the Domane’s go-anywhere abilities. With lengthy 42cm chainstays, a slack 71.9-degree head angle, and 100.8cm wheelbase, the Domane is very stable, and boasts generous tyre clearance, ideal for larger rubber, mucky roads, or for fitting mudguards to the hidden mounts.
Bontrager’s Isocore carbon bar incorporates gel pads for comfort and control, and the Affinity Pro carbon rail saddle proved popular.
It’s hard to find a weakness in the Domane SLR’s makeup. Cutting-edge technology doesn’t come cheap, but there’s a lot going on in that frame. It accelerates well, and tames rough surfaces like no fast road bike ever has.