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This month Specialized announced the newly designed Tarmac which continues the evolution of their successful Tarmac SL4. But calling it the SL5 would imply that it’s just a lighter, stiffer, faster step-up from the previous model. However, the intent was much more ambitious than that …
If I distill all the information coming from Specialized on the new Tarmac down to two words, they would be “improved handling”. The point of the new Tarmac was to alter the design methodology towards creating a bike optimised for a rider’s size rather than designing a bike based on 56cm measurements and simply scaling up or down (from a compliance and stiffness perspective).
According to the feedback Specialized received from riders and testing, the SL4 small frames were too responsive to steering input for optimal handling, while larger frames were not responsive enough. The goal was to design a bike that achieves its best performance at every size (from 49cm to 61cm and everything in between).
Specialized says there were power transfer targets also considered in the new Tarmac design (i.e. rear triangle design) where they also altered the stiffness for different frame sizes to achieve the best power transfer possible.
You might ask: don’t other brands design their bikes this way? I put this question to a number of major brands about the way they design and manufacture their frames, and the response was a resounding (paraphrased) “yes, absolutely we do.” The product managers I spoke with said that this is a “given” with bike design and it’s not something they’ve ever considered telling people about.
When I asked Specialized about this, the response from James Hibbard (Product Manager) was:
While other manufacturers do indeed make changes to the lay-up and tube shape of their various sized bikes, they make these changes to achieve those stiffness targets which are based off of the 56cm frame. What McLaren, and the new dynamic testing protocol has taught us is that these stiffness targets need to vary by size in order to achieve optimum performance.
So the real revolution that distinguishes Rider-First Engineered from size specific is not that there are changes to each frame size, but that the aim of these targets is not to achieve the same stiffness target — but different targets for each frame which have been established by the forces that the size rider of that bike will exert on it.
Now, the exact design methodology for each of the major brands and their various bike sizes can be debated, but I felt this was important to clarify since this is the foundation of the new Tarmac’s story and sets up buyer expectations.
Before the ride
The most significant visual difference you’ll notice between the new Tarmac and the SL4 is at the seatpost junction, where almost everything above the top tube has been eliminated. The disappearance of the extended seat tube means that a clever new binding system has been implemented to fasten the seatpost in place.
While most of the tubing looks the same from afar, the large downtube has been made slightly more elliptical to increase aerodynamics (a little like the Venge) and the seatstays are more tapered and curved. The chainstays are also more rounded than the exaggerated oval shape of the previous iteration.
Another exciting development is that the new Tarmac also features a disc brake frameset option which has identical geometry to the rim brake option.
Current Specialized owners will be pleased to know that the geometry of the new Tarmac is identical to the previous generation.
In terms of real-world weight, the 56cm weighs in at approximately 6.6kg (SRAM Red with Roval Rapide CLX 40 Wheels without pedals) and the 54cm (same spec) weighs 6.4kg. From reading other sources (unpublished by Specialized), the S-Works frame (56cm) weighs 966g and the fork comes in at 360g.
After the ride
The bike I test-rode was equipped with SRAM red, Roval Rapide CLX 40 Wheels, and S-Works SL bar/stem/seatpost. That’s very close to the specs of my current SL4 that I’ve been familiar with for the past couple years. The Roval wheels are one of the highlights in my opinion, but let’s focus on the bike itself.
I’m a 56cm frame-size and according to Specialized’s claims of their bikes previously being designed based on that size and then being scaled up or down, I came into this ride being skeptical that I would notice much of a difference to my SL4. The design philosophy certainly makes sense for edge-case riders at 49cm or 61cm sizes, but perhaps less so at the middle of the bell curve where I sit.
I rode the bike for a total of approximately 250km through the hilliest terrain I could find; my beloved Dandenong Ranges. I was keen to pay more attention to the descents rather than focus on the climbing because of the handling characteristics that Specialized designed this bike for.
But to go down you must first go up, and the first thing I could notice while climbing was the stiffer bottom bracket, especially when out of the saddle. When comparing the bottom bracket deflection on my SL4 to this new Tarmac I could barely tell the difference, but it certainly came out in the ride quality. There’s no doubt that it felt more efficient, but without the harshness of an overly stiff bike.
My colleague Andy van Bergen also took the new Tarmac out over the weekend and noticed a perceived difference in seated climbing efficiency over his SL4.
I have to be honest — when descending, neither of us could feel a noticeable difference between the SL4 and the new Tarmac in steering response while cornering. That’s not to say that it was bad; far from it. The SL4 descends beautifully and while I don’t claim to be the best descender on the planet, I’ve always been comfortable keeping up with any of the top-level riders I’ve been out with. Perhaps the smaller and larger riders will find a more pronounced difference, but I can only speak for myself. Andy is a 54cm framesize and also failed to notice a difference in cornering while descending compared to his SL4.
Don’t take this the wrong way, the Tarmac SL4 is a bike I’ve had the pleasure to ride for nearly two years now and is an incredible bike. In terms of ride quality, it’s a 9/10. Specialized was tasked with building an even better version of this, and I’m not sure it’s realistic to expect that revolutionary gains would be made. That said, their marketing claims might be just a bit big for what’s been delivered.
One problem with the bike I did have however was with the new seatpost clamp design. While very simple and effective, I did manage to accidentally make the fastening mechanism pop out and fall down the seat-tube when I took the seatpost out to discover how it worked.
The clamp is held in the frame by a small elastic band which breaks very easily if the seatpost catches while re-inserting. The trick (unknown to me until after this happened) is to tilt the frame such that the mechanism falls flush with the seat-tube while inserting the seatpost.
Since removing the seatpost is an extremely common thing to do (e.g. when travelling), this is something that will need to be fixed as I don’t think I’ll be the last person to encounter this. Also, in my experience, bolts that are set into the frame which need to be accessed frequently (such as this new seatpost clamp) will sometimes begin to chip away at the paint from the allen key knocking it. I obviously haven’t seen what longterm use will do, but it might be a concern for some.
So is the new Tarmac better than the Tarmac SL4? This is the question I asked myself when riding the new Tarmac. From what Specialized says, there’s three years of work that’s gone into the new Tarmac design. At my frame-size the result is better than the SL4, but only marginally.
I applaud Specialized for being able to improve on an already excellent bike and I’ve yet to see very many revolutionary leaps with bikes these days. Chipping away at marginal gains over the years is how bikes have gotten to where they are, and a few years down the road we’ll have seen massive advancement through many iterations.
I’m not sure that current SL4 owners will benefit from the upgrade but if it’s time to look for a new bike, the new Tarmac is without a doubt an absolute pleasure to ride that I’d recommend considering.
– S-Works Tarmac Disc: RRP $11,999 AUD
– S-Works Tarmac Dura-Ace: RRP $9,499 AUD
– S-Works Tarmac RED: RRP $9,499 AUD