Tires are something that I obsess over. Weight, rolling resistance, casing, size, pressure, and course conditions all contribute to defining what makes the ideal tire on a given day. Sheldon Brown said that tires affect ride quality more than frame material, and I have to say that I wholeheartedly agree with him.
This will be the first of many tire reviews that I'll be posting, with several tutorials about what makes a good tire along the way.
This post is about the Kenda Karma. The particular model that I've ridden is the 26 x 2.0 Stick-E version.
The Karma is a well-known and respected tire. The tread pattern is a fairly simple square block pattern, but that's only a small part of what makes this tire a good one.
To be fair, Kenda is a sponsor of mine, and their tires have been a great asset. I've enjoyed their support for two seasons now and have been grateful to have access to their full catalog of models and sizes.
The Karma is a fairly round casing with low, reasonably spaced and square-edged knobs. The round casing means that it takes the middle ground of rolling resistance between parabolic (like the Small Block 8) and square (like the Nevegal) tire profiles. That means it's lugs hit the ground when leaned over marginally and strike a 50/50 compromise between grip and rolling resistance.
The square knobs do well in soft soil as they provide consistent bite. The round shape keeps the center and some of the outside knobs in contact with the ground to provide moderate traction in softer conditions without putting too much rubber on the ground to slow things down.
There are no special cornering knobs, so you really need to lean these over to feel like the outer treads are working for you.
In mud these tires are decent at normal pressures but better at lower pressures. I found that I was the most comfortable on them at 3-5 psi below my normal 28-32 psi range. When run at 20-25 up front these provided decent cornering traction and good rolling resistance, but if I were in consistently slick conditions with lots of corners I'd probably choose something else (like the Nevegal 1.95 or Blue Groove 1.95- look for reviews on these shortly).
In pure hardpack these tires were predicatable and spun up fast because of their low weight, but they felt like they skated slightly at higher speeds when I would have liked to get a bit more grip. Again they were fine, but if I were rolling on pure hardpack I would prefer the excellent Small Block 8 instead.
So what are these tires good at? Well, they're good in intermediate conditions, especially in soft, loamy soil when climbing is a big part of the agenda. Their light weight makes them spin up very easily and the lack of mass is palpable when climbing. The downside of that is that the light sidewalls are less resistant to sidewall cuts than heavier tires, so if you ride in rocky terrain you might want to run something more substantial. The round casing does well to keep just the center knobs in contact with the ground when pedaling a straight line, and the square knobs do well in softer soil where they can bite. The knobs are fairly shallow keeping the rolling resistance reasonable and they're spaced far enough apart that they clear mud easily.
At the rain-soaked Bromont World Cup in 2009 I noticed that Nino Schurter ran a Karma (with the logos blacked out) as a front tire. They aren't a pure mud tire, but they are predictable and a reasonably good jack-of-all trades option.
In short these are great intermediate ties. In my perfect tire quiver they sit between the Nevegal (for moderate t0 wet/loose conditions) and the Small Block 8 (pure hardpack) and provide predictable traction in most conditions. These are a great choice for intermediate conditions that will feature a bit of everything, especially soft, loamy soil. Hills are easier due to their light weight, but be cautious of sharp rocks as they can be cut fairly easily.
More information is available at www.kendausa.com.