Bikes and Tech
Trek's new Domane SLR takes IsoSpeed technology...

Trek unveils new Domane with flexible head tube

The company's latest version of the comfortable endurance bike features a decoupler in both the seat tube and the head tube.

We saw Fabian Cancellara win Strade Bianche on it, and we saw him rocket over the cobbles in the 2016 Ronde van Vlaanderen (Tour of Flanders) to a second-place finish on board the new Domane SLR from Trek (check out the gallery of Cancellara’s Flanders bike here). Now we’ve got details about the striking new bike that has both a redesigned IsoSpeed decoupler in the seat tube as well as a brand new decoupler in the head tube.

Yep, you read that right: The head tube moves.

To be more accurate, the fork’s steerer moves independently within the head tube. The general idea is that the fork’s steerer mounts into the decoupler at the top of the head tube assembly. The decoupler mounts to the head tube via two bolts, one on each side of the head tube, and it freely pivots fore and aft. The fork’s steerer then slides within this pivoting damper to provide some compliance. The bottom headset bearing appears to be fixed as normal, which means the decoupler relies on steerer flex to work properly.

The new system addresses some of the unbalanced feel previous IsoSpeed bikes could deliver: The rear felt supple and compliant, while the front of the bike remained relatively stiff. Now with decouplers front and rear, riders can experience that compliance throughout the bike.

Let’s get back to where it all started: the rear IsoSpeed decoupler does what previous iterations have done by tempering road vibrations using some version of a moving tube. But this current iteration is completely different — and adjustable. A slider moves within the system from low on the seat tube for the most compliance, to high on the seat tube for less compliance and more stiffness. This allows the IsoSpeed system to be tailored to a specific rider — lighter riders can now get more compliance, and heavier riders can dial down the movement so the bike doesn’t feel quite so squishy.

The decoupler is comprised of an independent tube that’s mostly flattened from where it attaches to the seat tube at the bottom bracket shell, all the way up to just beneath the top tube. It is then affixed to the seat tube at two points: down low by the BB shell, and up high at the top tube. A slider moves between the flattened tube and the seat tube to adjust compliance.

Trek adds a new Bontrager IsoCore handlebar to further reduce front end chatter. IsoCore is essentially a proprietary laminate that’s worked into the carbon layup. No word yet on what exactly that laminate is, or how it affects vibration, but it’s hardly a new idea. Companies like Bianchi use similar additives to carbon layups — like Bianchi’s Countervail — to help take some of the sting out of the road before it reaches your body.

Other touches include Trek’s rim brakes that allow for plenty of tire clearance — 28c on rim brake bikes and 32c on disc brake bikes — a control center port on the down tube similar to the one found on the Madone (except this one hides the battery rather than the junction box), and thru-axles.

The Domane is designed with Trek’s Endurance geometry, which means a taller head tube and a more stable, slightly upright position. The Pro Endurance geometry keeps racers in mind with a more forward, aggressive riding position, a shorter head tube, a longer wheelbase, and a lower bottom bracket.

Got questions? Yeah, so do we. Does this movement put added stress on the steerer? What about that bottom headset bearing?  Does it result in brake shudder under heavy braking? What about a sloppy steering feel? We don’t have the answers to that yet, but we’ll be riding the Domane in the coming days right where it’s meant to be ridden: on the Flanders cobbles. So we’ll know definitively what this bike is all about soon; keep an eye out for our First Ride report.

Several builds and configurations will be available from Trek:
Domane SLR 9 eTap: $10,999
Domane SLR 7 Disc: $6,499
Domane SLR 7: $5,999
Domane SLR 6: Disc $5,499
Domane SLR 6: $4,999