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To create the vests, hats, mittens and slippers that she felts from wool, Katharine Jolda spends several hours a week on a stationary bicycle. She calls it a CycloCarder, a pedal-powered drum carder she invented to process wool.

"The idea comes from the cotton gin," Jolda says. "There's two drums covered with wire brush cloth that rotate against each other like two hairbrushes. They brush the wool out, get the fibers all in a line, and then the dust and manure and bugs and burrs all fall out."

Because she lives on a 25-foot sailboat in the Berkeley Marina, Jolda sets up her CycloCarder in the driveway of her parents' home in Piedmont. An avid bicyclist and a competitive rower in high school and college, she can card 3 pounds of wool in an hour through pedal power.

She even has a cycle computer that calculates how far she rides. "So, for each item I make, there's an mpg number: miles per garment."

Jolda, 30, went to Piedmont High and has a bachelor's degree in political economy from Northern Arizona University. She speaks softly and initially seems wispy, hesitant. But there's a sturdiness to her - a combination of hippie idealism and mechanical acumen, a gentle demeanor and sharp focus.

The inspiration for her felt work, Jolda says, were the six "transformative" years she lived on or near the Navajo Nation in northeast Arizona. She worked with Healing Gardens, a farming-based diabetes prevention program, and spent several seasons herding sheep with Rena Lane, a Navajo woman who raises sheep and goats.

Jolda goes back every summer to buy fresh-shorn wool from Lane and other sheep-raising families. The development of the CycloCarder, she says, is directly related to her desire to support her Navajo friends with prices that "honor their work." She also sources wool from Bodega Ranch in Sonoma County.

When she started felting, Jolda used a hand-crank carder. "I was noticing that it was hurting my shoulder." A hobby bike builder, she started thinking about how to utilize bicycle technology. "The mechanics seemed to line up so nicely."

Her first CycloCarder prototype used all bicycle parts - chains, chain rings and sprockets - but didn't work "because I couldn't get the rotation ratio between the drums high enough. The higher the ratio means the wool is transferred more slowly from one drum to the next, so there's more opportunity for fibers to be brushed into alignment."

Eventually she found sources for timing belts and pulleys that better suited her needs and created her own pulleys and other parts. Jolda built an oak box to house the drum system, mounted it on an old bike frame and removed the wheels to make it stationary.

"For a year, I was constantly redesigning, refining. I rebuilt it into this one that I'm using now, which works great."

Her long-range vision for the CycloCarder, she says, is to enable more small-scale producers of sheep and woolen goods to get their products into use. To that end, Jolda has built and sold four additional CycloCarders for sites in California and Washington, and worked with an industrial designer on professional plans for building CycloCarders from scratch.

The clothing she makes, under the name Felt the Sun ( www.feltthesun.com), is durable and warm and features natural wool colors and other raw materials: buttons made from deer antlers, black walnut shells and pieces of abalone shell.

Jolda buys the fresh-shorn wool in large bags and selects fleece varieties that have fibers about 6 inches long to "make a strong network." Then she runs it all through her CycloCarder. When it's brushed out, she arranges layers of wool fibers on a bamboo mat and soaks them in hot, soapy water.

"The heat and the alkalinity from the soap make the fibers swell and allows the scales on the fibers to open up. When it's primed that way, I begin to rub it and vibrate it and agitate it - very gently at first. I do it all with my hands, coaxing the wool. Not even any tools."

There's no weaving, no spinning of the wool involved. Friction causes the wool fibers to tangle and become felt.

When she started making clothing from felt, Jolda made large rectangles of felt, cut them into patterns and sewed them together. "Now I make the vests and jackets all in one piece: an entire piece of felt, with no seams. It's a much slower process, but the final garment is stronger, because it's made as a whole."

Jolda sells her work at the Berkeley Ecology Center's farmers' markets, at the recent Celebration of Craftswomen at Fort Mason and through word of mouth. She prices her garments based on the weight of the wool: her vests, for example, sell for $200 to $300 each.

People are surprised by the cost, she says, "which is why I'm trying to do a lot more teaching - so people know how to make their own."

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Edward Guthmann is a Bay Area freelance writer.