Rubena Scylla & Kratos 29″er Tires: First Impressions: by Guitar Ted

Well readers, it was mid-winter when I received the Rubena Kratos and Scylla tires for review, so I had to wait for the trails to become rideable again to get you all these First Impressions. It might be a good thing then to review the technical aspects of these tires here. Once you’ve refreshed yourselves on those tidbits, we can continue on with my impressions on these two European tires.

Scylla First Impressions: The Scylla was also provided on the recent Titus Rockstar bicycle in for review, (see here), and I had the opportunity to set the tires up on the UST spec Crank Brothers wheel set. They aired up rather easily, and held pressure very well on these wheels and on the Bontrager wheels I mounted the original pair up on. As far as tubeless performance, this model gets high marks from me.

The Scylla displayed a slippery nature in mud, and wasn’t the best in slop. Not to wonder at this with the low-ish knob height and rounded profile that this tire exhibits on the rims I have them mounted to. In softer grounds, the Scylla also tended to be a bit of a “cutter”, sinking into the soft dirt and making for a real work out. I figured that harder, drier trails may be where I would see this design come to its full potential.

In the Southwest, on my little excursion to the El Paso, Texas area, I rode the Scylla on some real unforgiving rocky trails. The Scylla gripped for everything it was worth, but really, it was almost beyond its capabilities here. Once again, I felt that the rounded nature of the casing was cause for some stepping out on off cambers. It wasn’t terrible, it was just there. Surprisingly, the grip, where the tire was not getting ricocheted off-line by fist sized rocks, was awesome. The compound that the Scylla uses is obviously a very grippy one, and it stuck to the rock for the most part quite nicely.

Okay, so the Scylla probably isn’t a severe conditions trail tire, but if you do find yourself on some rocky, unforgiving desert trail, the Scylla will be a serviceable tread pattern. Be aware though that due to the softer compound used the tire tread will show signs of abrasion. I noticed plenty of this after a multi-hour ride in the desert.

Kratos First Impressions: The Kratos is also a very nice, easy to get along with tubeless conversion. It shows the same air holding traits the Scylla does, so again, high marks as a tubeless tire. The nature of the Kratos is quite different beyond this though.

As you can see, this tire has an open, squared off knobby tread pattern with a unique “negative groove” right down the center of the tire. It would seem that no efforts were made to allow for a smoother rolling center tread section, as we find on many trail tires these days, but that the focus is on traction. Indeed, this is pretty much the case with the Kratos. On smooth, hard pack, or pavement to the trail head, you can feel the tire vibrate and that rolling resistance is a bit higher than some other tires. Once out on the trails, this tends to disappear for the most part.

I did find a strange sensation on softer grounds where the Kratos tread blocks were piercing into the soil and when the tire rolled and pulled the tread blocks up and away from the trail surface, a bit of drag was created. This reminded me of some old spiked mud tires I used to run 15 years ago. Not as bad as those, but similar. The Kratos is a grippy tire!

In fact, it reminds me a lot of a cross between a Bontrager Jones ACX and a Specialized “The Captain”. Tires that made little concession to being fast rollers, but were tires that had really good grip. The Kratos was great on the off camber broken rock turn on my test trail and did a great job digging in and propelling me forward on out of the saddle grunts on the Sawyer single speed. Grip is here in heaps, but something else that was a bit of a surprise showed up as well.

The Kratos showed me a nice, damped feel and rode like a big, fat tire. Bigger than the volume of this tire would suggest. I was running these at 27psi/1.86Bar front and 29psi/2.0Bar rear. Combined with the outstanding traction, it was a unique trail tire for sure.

So Far…. The Rubena tires exhibit two distinct personalities. The Scylla seems best suited for hard pack and racier terrain while the Kratos seems best suited to situations where grip is prized above all else. Both tires showed me excellent tubeless traits, easily set up and having very good performance on the wheels I have them set up on now. The tires both have a nice feel and are well constructed. The Scylla, however, does seem to be softer and shows abrasion when used on rocky terrain.

I’ll continue to put these tires through their paces as the summer comes on. Look for a Mid-Term Report coming up…..

Note: Rubena sent these tires for test/review at no charge to Twenty Nine Inches. We are not being paid, nor bribed for this review. We will strive to give our honest thoughts and opinions throughout.