Monday, 31 October 2016

Tech Talk: Trek Domane SLR

Trek Domane SLR

The Trek Domane may not have been the first endurance bike when it was launched in 2012 but it played a pivotal role in defining the genre of comfort-focused race bikes. Now Trek are back with the Domane SLR and have upped the ante once again. It’s an exceptionally comfortable machine – but one which, in its Pro Endurance geometry, retains the handling and responsiveness of a true race bike.
The second generation Domane SLR offers an improvement in ride comfort and smoothness over the previous model. Like the original Domane, this new version was developed with input from Classics specialist Fabian Cancellara. 

The original IsoSpeed concept relied on the entire seat tube to flex under bump forces but this latest Domane SLR borrows the current Madone’s twin seat tube design to separate structural and ride comfort roles. The new Domane SLR still incorporates a ‘decoupler’ at the seat cluster but whereas the original Domane’s seat tube and integrated seatmast were one continuous section, those parts are split apart on the Domane SLR and sandwiched next to each other with the smaller half behaving like a flattened leaf spring. 

Slide up or down to fine the right tune of rear compliance

The main seat tube is now rigidly attached to the top tube and down tube as on a conventional carbon fibre frame while the thinner, secondary seat tube is moulded as one piece with the no-cut integrated seatmast and anchored down near the bottom bracket. It’s this smaller, secondary frame section that passes through the IsoSpeed decoupler. “You’re using the seattube as the leverage point, just as you did in the original Domane, but now you have a level of adjustment,” says Ben Coates, Trek’s road bike product manager. “As you move the slider up, you reduce the compliance by using less of the seattube, and as you slide the slider down, you’re increasing compliance by using more of the seattube.” Moving it toward the bottom bracket yields the longest spring and softest spring rate; moving it up makes it progressively shorter and stiffer. According to Trek, the most comfortable setting is now 14% softer than before but the least is 25% more firm. Changing the ride quality requires just a few seconds with a 4mm hex wrench and your fingers.

The front Iso Speed Decoupler look like

The front IsoSpeed Decoupler allow fore and aft movement, but not side to side

A common complaint with the original Domane centred around the front end feeling much stiffer than the compliant rear end. To solve this, Trek has integrated an IsoSpeed decoupler into the head tube, allowing a specially shaped carbon fibre steerer tube to bend slightly between the two headset bearings. Normally, a bike’s front end will flex at the fork’s legs, and then a very small amount where the steerer tube protrudes above the top headset cap, plus a bit in the handlebar and stem. By adding a pivot in the head tube, Trek engineers allowed a much longer section of the steerer tube to flex. Since it’s anchored on either side, there is no laterally play in the steerer, so it feels like a normal bike when you are steering, climbing or cornering.

Bontrager dropbar with IsoCore

Trek’s Bontrager division contributed to the new Domane with a handlebar technology dubbed IsoCore. Sandwiched between the layers of carbon-fiber composite is a layer of thermoplastic elastomer. This layer reduces high-frequency vibration by 20 percent compared to a standard handlebar, Trek’s press-release states, and according to Coates only adds about 20 grams to the handlebar (claimed weight for a 42cm width is 249g). If this sounds somewhat familiar, it’s because IsoCore sounds a lot like Counterveil, which is found in the frame and fork of the excellent Bianchi Specialissima. The difference between the front IsoSpeed and the IsoCore handlebar, Trek say, is the former deals with big hits dished up by the road, while the latter is focused more on high-frequency vibrations. Combined with the adjustable rear IsoSpeed, Coates says the Domane SLR offers “an incredibly balanced front and rear end feel.”


Seattube: The tube where the seatpost going, its linked a downtube, toptube, chainstay and seatstay.

Toptube: The tube link between the headtube and seattube.

Downtube: The tube link between the headtube and bottom bracket.

Headtube: the head tube is the part of a cycle's tubular frame within which the front fork steer tube is mounted


Ride On!

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