Mountain Gear

Tech Gallery: Black Sheep one-off headed to handmade bike show

Ever try to define the term "functional masterpiece?" Let this one-off belt-drive singlespeed titanium 29er from Black Sheep do the talking (while you drool).

Read more about the Culebra below.

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Richmond, Virginia welcomes the North American Handmade Bicycle Show next weekend, but we stole a sneak peek at one of the artful bikes headed east for display. Singlespeeder Jake Kirkpatrick dropped by the office to show us his new belt-driven Black Sheep 29er race bike.

Just over a week since it was freed from the welding jig, Kirkpatrick’s newborn bike almost felt warm from Black Sheep owner and welder James Bleakley’s torch. However we soon realized it was just our own sweaty palms and flushed faces. The bike is sweet to look at, and it’s a great representative of the functional masterpieces that lucky NAHBS attendees will devour in just a week’s time.

Kirkpatrick has been riding custom Black Sheep titanium bikes out of Fort Collins, Colorado for the last few years now, and they’ve all incorporated curvaceous tubing and unique design elements. But this latest work takes it to a new level. They named it “Culebra,” which is Spanish for cobra, and it tips the scales, fully built with pedals and sealant in tires, at exactly 18 pounds.

Going Big for NAHBS

The most noticeable feature on the Culebra is its profusion of slender tubing composing the front triangle. Twin top tubes originate at the head tube and gracefully arc down the front triangle before rebounding to become the seatstays before terminating at the dropouts. Similarly, a pair of slender, parallel down tubes snake down to the bottom bracket. A single center tube bridges from the head tube to the seat tube, adding stability and contributing to the five total tubes that join the head tube to the rear of the bike.

Bleakley’s Black Sheep show bikes frequently sport welded titanium one-piece bar/stem combinations, and Kirkpatrick’s is no different.

“I wanted it to look like that old bullmoose style stem and bar,” said Kirkpatrick.

He said that Bleakley copied the rise and backsweep from a standard riser bar and stem to match his position preference.

Kirkpatrick works with Gates Carbon Drive Systems and uses a belt drivetrain. The drive side chainstay has a deep cutout to accommodate the wide chainring, and the chainstays use Black Sheep’s extendable, telescoping design to tension the belt. There is no upper pivot, but the seatstays flex enough to allow the chainstays to pull completely apart to pass the belt into the rear triangle, and setscrew bolts hold the chainstays in the desired position. Hatch marks on the inserts help ensure even chainstay length.

As with any good NAHBS show bike, details abound. The seat tube is extended into a road-style integrated seatmast. A stubby, 2-inch seatpost caps it off. The seatstay bridge is jet-cut with the shape of a sheep. The rear Breezer-style dropouts are also cut out. Like the frame, the fork is an elegant strut of curved titanium.

But possibly the coolest detail of all are the King titanium bottle cages welded into place on the frame. Kirkpatrick said that the metalworkers at King used thicker tubing so the welding process wouldn’t erode the cages.

“It’s cleaner and this actually adds support to the frame,” he said, pointing at the upper portion of the downtube bottle cage. The upper curve of the cage acts like a cross member welded between the two downtubes.

Kirkpatrick said that in the unlikely event that one of the bottle cages breaks, it’s easy to weld a new one in place. Well, easy for Bleakley anyway.

“It doesn’t take James that long,” said Kirkpatrick. “It’s easy for him.”

Culbera Comes to Life

The concept for the bike originated with Kirkpatrick and was worked up into a viable project by Bleakley. As show time drew close, Kirkpatrick described how Bleakley called him up to ask what was new or different in ideas for mountain bike frames.

“I was like, ‘I’ve got some ideas for you!'” said Kirkpatrick. “I was like, let’s do everything with dual tubes. I just drew it up on a sheet of paper and faxed it to him.”

Kirkpatrick pointed out that older Colnago road bikes once relied on twin down tubes, and certain Schwinn cruisers had twin top tubes, but he couldn’t recall seeing the twin tube approach employed as extensively as he and Bleakley had done.

The two have a good collaboration when it comes to conceiving one-off mountain bikes.

“We always go back and forth,” said Kirkpatrick. “I’m like, hey James, I’ve got this idea.”

Working together, the two incorporate concepts and then Kirkpatrick ventures out on the trails to test the finished products.

The Culebra spec sheet reads like a five-star menu of tasty and lightweight parts. The bike rolls on Continental Race King 2.2 tires, which are strapped to 32-hole Stan’s ZTR Crest 29er rims, laced with DT Swiss Revolution spokes on 240s hubs. Exustar E-PM28ti pedals turn the FSA K-Force Light cranks, linked to a Gates carbon belt. Magura Marta SL Magnesium brakes bite down on Scrub aluminum disc rotors. The saddle is a $320, 130-gram fi’zi:k Antares 00.

“It’s sexy,” said Kirkpatrick. “You can sit and look at it for a while and notice more and more things.”

Really? We hadn’t noticed …