2012 Charlie Cunningham 29er #E1CC
As a Berkeley-trained aerospace engineer, Charlie Cunningham recognized early on that large diameter wheels roll over obstacles better, while lightweight construction allows them to accelerate up to speed quicker. After producing dozens of aluminum mountain bikes with smaller 26” wheels, Charlie built for himself what he called an Expedition or Speed Racer bike with a durable aluminum frame for bigger 700c wheels. Of course, Charlie’s desire for big wheels was hampered at the time by limited tire choices with any significant volume. In the European 700c size he might find tires as big as 28 mm in diameter for touring bikes, while for 27” it was limited to 1-3/8” (about like today’s 32 mm cross tires) with low-quality gum-wall construction. A breakthrough occurred in 2001 when Wilderness Trail Bikes was asked to develop a “29er” version of its popular Nanoraptor 2.1” tire. Finally, this was a big wheel tire that had the volume required for rugged off-road use, and what Charlie had wanted to build a bike around for decades. This tire would be used by the likes of Gary Fisher, Kent Eriksen, Don Cook, and Wes Williams to pioneer modern big wheel bikes. Unfortunately for Charlie’s efforts it had been nearly 10 years since he built his last aluminum mountain bike creation, and he would soon leave WTB. Making matters worse, his post-weld heat treatment oven for frames had long gone into disrepair and been taken over by critters. The possibility of a 29er Cunningham would need to wait another 10 years when two of his biggest fanatics would motivate and fund him to rebuild his oven. The result in 2012 was the production of just three big wheel Cunningham bikes, with the example presented here being the one Charlie built for himself. The bike would end up being the aluminum pioneers very last mountain bike.
The frame itself follows the classic design of a late-model Cunningham, from the sloping toptube, big seatpost, rear facing dropouts, and organically shaped gussets. Less obvious are the subtle hourglass shape of the headtube and concave center of the bottom bracket shell. The fork is a tried-and-true Cunningham Type II, which Charlie designed in the very early 80s before unicrown fork blades first became available. Charlie was aware that bigger 29er wheels would be sluggish compared to their 26er counterparts with the same frame geometry and wanted to keep the handling quick. As a result, the headtube angle is road bike steep at 73.5 degrees while the seattube angle is similarly steep at 74 degrees but on par with modern racing hardtails. Charlie went to great lengths to keep the chainstays as short as possible at 430 mm, in part by making the compromise that the largest rear tire that will fit is a 1.95 inch, and even that is very tight. The wheelbase comes in at 1070 mm or a touch over 42 inches, which surprisingly, is equivalent to his late-80s, Racer model 26er mountain bikes. Component wise, one's eyes are immediately drawn to the scissor-style “Lever Link” brakes. As the last and best iteration of his patented Rollercam brake arm design dating back to the early 1980s, the mechanical actuation is through a pair of linkages. By request, Charlie left the brake arms roughly milled rather than, in his words, “fiendishly” finishing them to look like they were made by machines. Charlie always preferred that his bike visually speak clearly to say, “I was made with care by hand.” Should the handlebars be turned too tightly, the top of the Lever Link brake would contact the downtube and be damaged, so Charlie developed a simple steering limiter. A parachute cord tether runs from a titanium strut attached to the back of the fork crown to an anchor point on the bottom of the downtube. While the bike is retro in style, the design has the modern element of “Boost” dropout spacing: 118 mm in the front and 145 mm in the rear. Charlie put in a heroic effort to have short 430 mm chainstays with a triple chainring crankset while also maintaining the narrow 154 mm Q-factor of a road bike (pedal to pedal spacing). Everything is tight everywhere and requires sub-millimeter modifications. There is practically no bottom bracket spindle showing, which is even more impressive since the bottom bracket shell is only 70 mm wide (not Charlie’s typical 80 mm). After looking at the numbers, it should come as no surprise that the bike rides like a rocket ship. It climbs technical terrain incredibly well while being a little nervous on the downhills. Charlie accomplished his goal of having the advantages of big wheels combined with low weight and the quick handling characteristics of the small wheel bikes he had ridden for decades.
More information about Charlie Cunningham bicycles can be found on the Charlie Cunningham Photo Archive page.
The frame itself follows the classic design of a late-model Cunningham, from the sloping toptube, big seatpost, rear facing dropouts, and organically shaped gussets. Less obvious are the subtle hourglass shape of the headtube and concave center of the bottom bracket shell. The fork is a tried-and-true Cunningham Type II, which Charlie designed in the very early 80s before unicrown fork blades first became available. Charlie was aware that bigger 29er wheels would be sluggish compared to their 26er counterparts with the same frame geometry and wanted to keep the handling quick. As a result, the headtube angle is road bike steep at 73.5 degrees while the seattube angle is similarly steep at 74 degrees but on par with modern racing hardtails. Charlie went to great lengths to keep the chainstays as short as possible at 430 mm, in part by making the compromise that the largest rear tire that will fit is a 1.95 inch, and even that is very tight. The wheelbase comes in at 1070 mm or a touch over 42 inches, which surprisingly, is equivalent to his late-80s, Racer model 26er mountain bikes. Component wise, one's eyes are immediately drawn to the scissor-style “Lever Link” brakes. As the last and best iteration of his patented Rollercam brake arm design dating back to the early 1980s, the mechanical actuation is through a pair of linkages. By request, Charlie left the brake arms roughly milled rather than, in his words, “fiendishly” finishing them to look like they were made by machines. Charlie always preferred that his bike visually speak clearly to say, “I was made with care by hand.” Should the handlebars be turned too tightly, the top of the Lever Link brake would contact the downtube and be damaged, so Charlie developed a simple steering limiter. A parachute cord tether runs from a titanium strut attached to the back of the fork crown to an anchor point on the bottom of the downtube. While the bike is retro in style, the design has the modern element of “Boost” dropout spacing: 118 mm in the front and 145 mm in the rear. Charlie put in a heroic effort to have short 430 mm chainstays with a triple chainring crankset while also maintaining the narrow 154 mm Q-factor of a road bike (pedal to pedal spacing). Everything is tight everywhere and requires sub-millimeter modifications. There is practically no bottom bracket spindle showing, which is even more impressive since the bottom bracket shell is only 70 mm wide (not Charlie’s typical 80 mm). After looking at the numbers, it should come as no surprise that the bike rides like a rocket ship. It climbs technical terrain incredibly well while being a little nervous on the downhills. Charlie accomplished his goal of having the advantages of big wheels combined with low weight and the quick handling characteristics of the small wheel bikes he had ridden for decades.
More information about Charlie Cunningham bicycles can be found on the Charlie Cunningham Photo Archive page.
The Build
Year: 2012
S/N: #E1CC Frame: Cunningham Big Wheel Fork: Cunningham Type II Stem: Cunningham Headset: WTB / King Grease Guard Bottom Bracket: Cartridge Bearing Grease Guard Handlebar: WTB Titanium Shifters: Shimano XTR M970 Front Derailleur: Shimano XTR M971 Rear Derailleur: Shimano XTR M972 Brake Levers: Shimano XTR M952 Front Brake: Cunningham Lever Link Rear Brake: Cunningham Lever Link Crankset: Middleburn RS7 Modified Chainrings: Middleburn 22-30-40 Pedals: Shimano T-100 Modified with Toe Flips Front Hub: WTB Grease Guard 118 mm Rear Hub: Chris King Classic Tandem Rims: Pacenti SL23 Tires: Specialized Ground Control 29 x 1.95/2.1 Wheel QR: Cunningham Slow-Release Seatpost: Cunningham Fixed Angle Seatpost QR: Cunningham Saddle: WTB SST.98 Titanium Grips: Magura Pow-R-Grip Modified Cogs: Shimano XTR M970 12-34 Chain: Shimano CN-HG93 Bottle Cage: Nitto Modified |
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