Look, Ma -- no chains

The 24 Hours of Adrenalin Solo World Championship is often a grueling showcase for the world’s toughest bikes and riders, but the July event in Canmore, Canada, was something special. Greg Martin, a 37-year-old firefighter from Ketchum, Idaho, won the single-speed division (and came in fifth overall) on a bike that didn’t have a chain. It used a smooth, silent, carbon-polyurethane belt.

With dedicated chain rings required to match the studded belt, this Carbon Drive system from Gates, a leading motor-vehicle belt supplier, isn’t cheap. But the system offers a number of benefits over the chain. It’s lighter; doesn’t use grease; requires no maintenance; won’t break, stretch, rust or fall off; and, best of all, it offers a pronounced improvement in “engagement” -- the millisecond it takes for the bike to react to your pedaling forces.

Each of the four reviewed bikes below (reflecting categories that are best suited to belt-drive) delivered an instant reaction.

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Single-speed champ

Spot SS 29er: Steel-frame, front-suspension, single-speed, Carbon Drive replica of Greg Martin’s world championship bike. Features oversized 29er wheels, disc brakes and a Maverick SC32 inverted fork with 4.75 inches of travel.

Likes: With my whole body sharing the work, I finished a solid 21/2-hour climb in the Santa Anas uncharacteristically fresh. With the belt’s lack of a time lag and the fork’s vertical engagement with the massive 7/8-inch diameter front hub, the bike jumps when you say so. The inverted fork also stays naturally lubed and dirt-free better than conventional forks. The steel frame is light, durable and will hold its lively ride feel for decades. Finally, Spot’s unique “slider” rear dropout makes wheel removal and proper belt positioning easy and simple. Weighs 22 pounds.

Dislikes: None -- except the price.

Price: $4,400. (303) 324-8313; www.spotbikes.com.

Caffeinated commuter

Trek Soho: The first Carbon Drive bike, introduced in 2009, is a stylish, aluminum-framed commuter-coffee road bike with Shimano’s eight-speed internal-geared hub, puncture-resistant tires, fenders and a fancy insulated thermos.

Likes: Fast, aggressive, nimble handling and great out-of-the-saddle hill-climbing for fitness and commuting. That’s due to the lean-forward, mountain-bike positioning, 700C road wheels, and an eight-speed drive train with a potent 55-tooth sprocket. Cool styling, including a muscular top tube. 32 pounds.

Dislikes: No commuter rack included (although it has front and rear rack eyelets). Mushy drum brakes (instead of better disks) don’t cut it for potential high speeds and hills. A lack of quick-release hubs hinders easy transport and quick flat-fixing.

Price: $1,149. (800) 313-8735; www.trekbikes.com.

Touring machine

Co-Motion Americano Rohloff: Deluxe, steel-framed long-distance touring bike with disc brakes and the acclaimed Rohloff Speedhub 14-speed internally geared hub.

Likes: Possibly the world’s most durable, trouble-free tour bike, an invaluable asset on mega-mile round-the-world journeys through off-the-beaten-paths hot spots such as Botswana, Kazakhstan and northern Nevada. The belt drive and Rohloff rear hub eliminate the need for finicky derailleurs and provide an acceptable range for flatland flying and steep hill climbing. Classic looks. The durability is worth the tradeoff of the extra-heavy hub, and it isn’t that big a deal on loaded touring. 27.4 pounds.

Dislikes: Cumbersome shifting.

Price: $5,446 ($5,146 with standard chain). (866) 282-6336; www.co-motion.com/single_bikes/amerohloff .html.

Shop till you drop

Specialized Globe Live 03: Deluxe eight-speed, aluminum-frame “shopping bike” with a large front rack, wraparound handlebars, disc brakes, bell, kickstand and fenders from Specialized’s new Globe division.

Likes: Rides great, with a super-comfortable, upright-back riding position -- perfect for casual riders out for neighborhood errands and fun, functional fitness with friends. A limiter spring helps keep your handlebars under control while steering. 33.5 pounds.

Dislikes: No hard-core hammering; the 46-tooth sprocket limits top-end speed. Also, the large open gaps and shallowness of the rack diminish its functionality.

Price: $1,550; (Similar models, with standard chain drive, run $940 and $580.) (408) 779-6229; specialized .com or globebikes.com.

-- Roy M. Wallack