The 650B wheel size may be enjoying an increased wave of popularity, but tire choices still pale in comparison to the 26″ (ISO 559) and 29′er/700C (ISO 622) sizes.  The good news, however, is that the current crop of 650B offerings includes high quality tires such as SOMA Fabrications’ B-Line model.

The made-in-Japan B-Line utilizes a standard nylon casing (with traditional tan sidewalls) and a raised Panaracer Pasela tread.  The advertised weight is 380g, and SOMA claims a width of 38mm.  The company also offers a more puncture-resistant model–the New Xpress–which features a HyperTex casing with the same tread pattern. Since I was looking for maximum width, I opted for the B-Line over the Xpress (the latter’s stiffer casing reduces the tire’s ability to expand to the full 38m width).

Mounting the B-Lines on Velocity Synergy rims was a breeze.  My past experience with similar tires (700x32C Paselas) had me concerned about possible hops or wobbles, but the B-Lines mounted true with only minimal adjustment of the beads.  Inflating the tires to 55-60psi resulted in the familiar “pop” of the beads seating into place.  Within a few days, the tires measured 37mm when pumped up to the maximum 75psi.

The SOMA B-Line mounted in Velocity Synergy rim.

The first ride on the B-Lines revealed a plush, “magic carpet” ride.  Rough, or broken pavement went essentially unnoticed.  The ride was comfortable, but still felt very lively.  Cornering was predictable, and the SOMAs made the tell-tale “hum” that I’d come to expect from a high-quality tire (especially when descending).  After some experimentation, I found the sweet spot to be 40-45psi up front, and 47-52psi in back (for paved riding).

While certainly not a dedicated off-road tire, the B-Line is quite capable on gravel and dirt roads. Dropping the pressure 10-15% made a dramatic difference in traction and comfort (I’ve run them as low as 33psi, and I weigh 200 pounds).  The tread grips well on hard-pack dirt, but can get overwhelmed in very loose or deep conditions (which is true of other, similarly-treaded tires).  My daily commute includes several miles of dirt and gravel, and while I was initially concerned about potential damage from rocks, the tires have shown good wear resistance.

If you’re looking for a lively, comfortable 650B tire that isn’t afraid to do some off-pavement exploring, definitely consider the B-Line.  You can purchase them directly from SOMA Fabrications, or your bike shop can order them from The Merry Sales Company.