drwelby
Rawland, working with Compass Cycle, just announced the Ravn:

Ravn Complete Pre-order

The interesting things about this bike that will baffle most people is the return to 26" wheels. Compass Cycle is releasing a new 26" x 55mm tire called the Rat Trap Pass that will be a super high volume version of their supple, lightweight tires. To make that volume easier to fit in to the frame with fenders and low-q drivetrains they chose to drop the rim size instead of trying to make it work with 650b or 700c rims. The outside diameter is close to a 650b x 42mm tire and has a similar 'feel' in terms of rotational inertia.

There is more information in the forthcoming Bicycle Quarterly magazine, which hasn't made it out to me in Colorado yet. So far I've heard that they wanted to test the limits of tire volume. They had a test bike that was built like their usual rando bikes but could take 26" mountain bike wheels and tires. Panaracer made them a pair of one of their mountain bike tires but used the lightweight casing material Compass usually specifies for their tires. BQ then had Peter Weigle shave the knobs off to make it a comparable slick. They were so impressed with the performance on gravel roads that they decided to make the tire real.

Rawland at the same time wanted to make a new model inspired by the Oregon Outback race, and in talking to Compass found out about this new tire. The Ravn is the result.
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ayjaydee
Wow! This is a very interesting development! I don't think I've ever ridden 40 mm trail. 
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