Not another gear blog again...Stumpy evo so far and compared to the venerable Five

As you might nor might not know, I dented the poor orange and had to get a last minute replacement. Thanks to good friends and a bit of luck a Stumpy evo frame fell into my hands. As I have said, the geometry is very similar to the Five, and almost all components are the same.

Orange Five, newly built in the beginning of 2013

I rode the Five for two more or less full seasons, in everything from Wyoming and Colorado to Norway and France. I feel quite confident that I got to know the bike really well, and even if I for obvious reasons can't ride the Five and the Evo back to back, I still should be able to pick out various differences.

I have now ridden the Evo more or less every day since I came to Spain, and many days I have put in 2000m of descending or more. In other words, I have descended thousands of meters and climbed thousands of meters on the Evo and think that I know it well enough to be able to give a first impression at least.

Stumpy Evo, mostly covered in dust save for the front wheel

Starting off, the Evo is about 8mm shorter in the reach than the Five. This does not sound that much, but it makes a difference. It feels more agile at low speeds and when playing around, but when pushing it at higher speed and in corners it is not as easy to find the sweet spot for weight distribution as it was on the Five. Probably contributing to this feeling is the 5mm shorter chain stays on the Evo, further reducing the wheel base. Don't get me wrong, the evo is still plenty stable, but the Five was even more so.

However, the upside of the short chainstays (I think, it might be more to it than that) is the uncanny ability of the Evo to be steered by heels and hips, sort of riding the back wheel. The only other bike I have ridden that gave the same sensation was a Spec Demo, making me think that this is something Specialized look for specifically when they tune in the handling of their bikes. I like it, a lot. Maybe not the fastest way to ride, but it sure is fun.

Then there are a couple of practicalities with the Evo that are annoying:

1: Headset. Why o why campy style internal instead of a proper head tube that I could put a Hope or Cane Creek headset in. It is just unnecessary and creaky and stupid.

2: Kinked seat tube. Limits my maximum seat post insertion, which is annoying. Right now I have my KS Lev 150mm inserted as far down as it goes, and I could do with a couple more centimeters lower. I lucked out, but could just as easily have ended up with a lot of seat post travel I could not use.

3: Press fit bottom bracket. I just cant see the point. Remind me again what was wrong with my xtr970 cranks? Light, stiff and cheap (used). Pick all three.

4: Swoopy down tube. Makes the bike harder to carry for long bike carries. Yes, I know that most people don't carry their bikes up mountains, but I do. And a straight down tube gives better weight distribution when the bike is on my back, it is as simple as that.

5: The Evo is lighter. It does not make much of a difference to me as soon as I am actually riding instead of lifting the bike in the parking lot, but nevertheless it is lighter.

6: Stiffness. I think that the rear end of the Evo is a bit stiffer, it just has a tad more solid feel to it. But it might just be my imagination, back to back testing is needed to confirm.

Then there is the suspension design, probably the biggest difference between the two frames. The Five is a high single pivot with a lot of antisquat designed in, the Evo a horst link with very little. Specialized themselves usually talk about "active suspension" and such, and the blunt way to say it is that by construction the Evo is not a very pedal efficient design. Of course, it can be remedied with tons of low speed compression in the shock, but that is besides the point, and negatively affect small bump compliance. So why do they do it then?

As I see it from trying both these bikes, there is an obvious downside to a design with lots of antisquat. Essentially, antisquat is obtained by making the chain tension counteract pedaling induced weight shift. This all sounds fine, but that also means that when the suspension goes through its travel, it will pull on the pedals. The Evo has a very "quiet" feel in the pedals when descending rough terrain compared to the Five. This makes probably an even bigger impact for riders on flat pedals, like me. The quiet feel makes it easier to keep control of the bike and ride it actively instead of just holding on for dear life. So even if the Five is more efficient, I actually prefer the slightly "mushy" Evo. And actually, when pedaling over rough ground, the Evo tracks the ground better and does not hang up as much on roots and rocks, since the rear suspension is more decouples from pedal input.

Speaking about single pivot vs Horst/FSR, some people claim that the Horst remains active when the rear brake is on. That might be true, but to be honest I can't tell the difference. Maybe I am just not sensitive enough, or maybe it has to do with riding style as well.

Another big difference is the rear shocks. The Five had a Bos Vipr, the Evo has a Fox ctd kashibling blahblahblah (with specific mounting as well, unfortunately). As you might guess, I prefer the Bos. It has a completely different feel to it, it does not wallow or lie deep in the travel, it just gives me as much as I need. Not more, and not less. Big part of this I think has to do with rebound damping. The Fox always seem to have to much or too little. Either it packs up, or it lacks control and wants to send me over the bars, and often I get the feeling that it is doing both at the same time. Especially after big hits there is a lot of pogo-stick feeling at the rear end. The Bos gives the impression to have super fast rebound, but is still controlled after big hits. I think it just has to do with superior hydraulics, the Bos has a lot more speed sensitivity in the rebound. It might be a matter of personal preference as well, but I always felt happier with the style of rebound the Bos offers. The compression damping is also more controlled on the Bos, but the difference is not as discernible to me.

So there it is, a bit of a comparison between two very similar and different bikes. If I got to design my dream bike from these experiences, it would be an Evo with a 10-15mm longer reach (but not higher seat tube, it is already high enough!) and possibility to mount a Bos shock. That sounds an awful lot like a Kona Process, if they could just make the chainstays a wee bit shorter. The low single pivot might in theory behave like the Horst of the Evo, and then I would see if the brake characteristics actually affect my riding style.