Trek Domane – the world’s best endurance road bike?

Criterium Cycles - Trek Domane SLR Project 1
Jan 31 2017

Trek Domane – the world’s best endurance road bike?

Looking at a modern road bike, one could be forgiven for thinking that it may be no more comfortable than one of those early Victorian boneshakers. For a start, there’s no obvious suspension. Who in their right mind would want to ride or drive anything on our roads these days without suspension? It’s going to hurt – a lot! Well, not necessarily but to understand why we’ve arrived at the design of today’s modern road bikes, we first have to understand what manufacturers are trying to achieve.


Victorian Boneshaker for us in Criterium Cycles Blog about Trek Domane - best endurance bike?

The Holy Trinity

Low weight, high stiffness, maximum comfort

A road bike is always going to have an element of compromise. After all, the manufacturer is trying to deliver an optimal balance between low weight, stiffness and comfort. The low weight bit is relatively straightforward. Materials science, both in terms of the type of materials used as well as the amount of material used has led to major leaps forward in design. Carbon Fibre in particular has led the charge. Whilst aluminium is still pretty lightweight stuff (as most of the world’s aircraft manufacturers will testify) it is the strength to weight ratio where carbon fibre wins. It’s just under 20% better than aluminium so you get the benefit of reduced weight and increased strength. That increased strength capacity allows the carbon fibre frame to be stiffer and that’s a good thing for all sorts of reasons.


Efficient Energy Transfer

The principal reason stiffer frames are a good thing is down to the efficiency of energy transfer. When you pedal your bike, you are converting your muscle energy into forward motion via a whole series of interconnected machines and systems. The linkages between those machines are where things can go wrong and you can dissipate a lot of energy for no benefit. Take for instance the cranks to which are attached your pedals and the bottom bracket through which those cranks are connected to the bike. If that whole area has too much flex in it, then some of your precious muscular energy is going to be lost in the sideways motion of the bottom bracket rather than being turned into forward motion through the cranks and the gears. So carbon fibre in particular has allowed bike manufacturers to create incredibly stiff frames with very stiff bottom brackets that ensure as much of your precious energy as possible is used to project you forward.


Criterium Cycles - Trek Domane downtube and BB90 Bottom bracket

Detail of Trek Domane large cross-section downtube and BB90 bottom bracket


Flexible is comfortable – stiff and compliant is possible

However, comfort is related to flexing (as in suspensions systems). Vibration transferred through any system is uncomfortable so motor manufacturers for example have developed ever increasingly sophisticated damping systems to make the ride of their cars as compliant and as cosseting as possible. But a car can weigh up to two tonnes and there’s a bit more ‘give and take’ in a system that big. A road bike weighs less than 10kg, often much less, so the bike designer has to work to far tighter tolerances.


The good news is that comfort and stiffness can co-exist because fortunately a road bike doesn’t have to be compliant in the same places it has to be stiff. Carbon fibre helps here because by using different lay-ups of carbon in different parts of the bike, areas of the frame can be optimized for the role that part of the frame has to play. Overall, a high quality frame needs to be laterally stiff (especially in the area around the pedals, cranks and bottom bracket) but vertically compliant to absorb shocks. How the manufacturers deliver this of course depends on their approach to material science and design. In this article, we are going to focus on how Trek approach the problem with their award winning road endurance bike, the Domane.


History of the Domane

Criterium Cycles - Trek Domane 2013 Model Year in Brushed Denim

2013 Model Year Trek Domane 4.3 WSD Compact seen here in Brushed Denim

The Trek Domane was launched in 2012 and its focus at the time was straightforward – to create a machine that could cope better than anything else on the fabled Cobbled Classics of Northern Europe and give its top riders, notably Fabian Cancellara, an advantage (a perfectly legal one we stress) in competition. The key feature of the Domane is a mechanical device called IsoSpeed that is basically a seat tube suspension system. Rather than the joint between the Seat tube and the Top Tube being rigid, with IsoSpeed the two tubes can rotate about each other permitting the Seat Tube to flex fore and aft (principally) without compromising frame stiffness in other planes.


Improved Comfort of Domane


The comfort improvements on those first Domane’s were dramatic with Trek at the time claiming a 50% increase in vertical compliance without any major sacrifices in other performance characteristics. And it didn’t end with Rear IsoSpeed. Trek also introduced a completely new fork design on Domane also labelled IsoSpeed. The IsoSpeed fork featured a raked design that swept forward increasing the wheelbase and softening the ride further. Trek coupled the sweeping design with vertical dropouts to ensure the overall result was relatively conventional in terms of wheelbase (though it is longer than traditional) to deliver a more relaxed geometry. Despite that, the fork provided both gains in comfort as well as lateral stiffness improving both handling and comfort. Trek added IsoZone pads on the bars (basically gel pads) to further insulate the riders from the brutal cobbles.


Cancellara wins on Trek Domane


It worked. Cancellara won E3 Harelbeke in 2013 (although he had won it in 2010 and 2011 as well), Tour of Flanders in 2013 and 2014 and Paris – Roubaix, the daddy of them all, in 2013, all on a Domane.


Fabian Cancellara en route to winning the 2016 Strade Bianchi

Fabian Cancellara en route to winning the 2016 Strade Bianchi on a Trek Domane SLR

Comfort for the Masses

The Trek Domane  could have been seen as a niche ride, one for specialists trying to win Cobbled Classics which let’s face it, is not going to be something that the vast majority of us aspire to. However, Trek realized they had a winner on their hands. For the Sportive rider looking for a bike that was supremely light and fast yet forgiving if you wanted to spend say 4 – 6 hours in the saddle, the Domane was a hit. On Britain’s less than adequate tarmac, the Domane was a godsend for those trying to get that optimal balance of lightness, stiffness and comfort.



Adjustable IsoSpeed and lots more


Criterium Cycles - Trek Domane SLR Adjustable Rear IsoSpeed Decoupler


The Trek Domane has continued its development. The biggest innovation and upgrade came in 2016 with the launch of Adjustable Rear IsoSpeed and front IsoSpeed on the range topping Domane SLR. Adjustable Rear IsoSpeed works by effectively splitting the Seat Tube into two parts with the IsoSpeed decoupler at the top and a bolt at the bottom creating something that works similar to a leaf spring. An adjustable slider is sandwiched between the two blades and this slider can move up and down increasing (or decreasing) the amount of flex in the ‘leaf spring’ arrangement. In practical terms, this allows the rider to change the amount of fore-aft flex. On smooth tarmac, the rider may opt for relative rigidity. On rougher surfaces, the rider may instead opt for a much more compliant ride. Trek claim a 14% increase in compliance compared to the original Trek Domane yet achieve Emonda levels of stiffness in the least compliant setting.


Criterium Cycles - Installing Isozone pads on a Trek Domane SLR

Criterium Cycles building a P1 Trek Domane SLR and inserting the IsoZone pads on the IsoCore bar


IsoSpeed on the front as well

That’s all wonderful news for the rear end but the new Domane also addresses one of the issues that came with the original Domane; the front cockpit. Ironically, the success of the rear IsoSpeed on the original Domane led to some riders feeling there had been a kind of compensating increase in rigidity in the front end. So Trek developed Front IsoSpeed that places top headset bearings in an aluminium basket that is bolted to the Head tube. This allows the top bearings to pivot fore and aft permitting the steerer to flex fore and aft. Yet it is fixed in the lateral plane to ensure accurate, precision steering. Trek claim a 10% improvement in compliance at the front end with no negative impacts on handling. To top it off, Trek introduced their new IsoCore handlebar that introduces an inter-laminar rubber into the carbon lay to dissipate road vibrations. Trek claim a 20% reduction in high frequency vibrations through the hands.

Check out this video from Trek explaining the development of the Domane SLR.


Disc Brakes

This being 2016/2017 of course disc brakes are also fully integrated into the Trek Domane  range. The Disc versions adopt a flat mount caliper and 12mm thru-axles to improve stiffness. Plus they have plenty of clearance and can take 32mm tyres in the Disc version as well as mudguards. This is one serious winter bike as well!


So is it any good and which should you choose?

We think it is better than good. Paul, one of the owners of Criterium Cycles rides a Trek Domane SLR (the one with Adjustable Rear IsoSpeed and Front IsoSpeed etc) and he thinks it’s pretty much the best bike he’s ever ridden. Period. So if you are looking for a bike that is going to be very fast (light, stiff and precise) but which when you ride for 4 – 6 hours and get out of the saddle still feeling comfortable then, as long as it is also professionally fitted, this bike is pretty much the very best there is out there.


Call for Details

For further details on Trek Domane call Criterium Cycles on 0131 663 6220.

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