Engineer Pass is a gravel road, which matters, because up here the word gravel means rock, ruts, shale, creek crossings and exposure. At nearly 3,900 metres it is the highest point on the Alpine Loop, the long dirt circuit that links Ouray, Silverton and Lake City through the heart of the San Juan Mountains, and it is a proper high-country dual-sport ride. This is no place for a heavy tourer or an inexperienced rider on a road bike. A light adventure bike with good tyres, a competent rider and a sensible start time make it a different story.
Everything about the scenery is vast. The pass sits above treeline in a world of scree slopes, tundra and ragged peaks, with the colours of the rock shifting from rust to grey to yellow as the minerals change. The San Juans are volcanic in origin, shaped by huge eruptions and then carved by ice, and the Colorado mining boom that followed in the 1870s left its mark everywhere: old tailings, collapsed cabins, rusting machinery. Roads like this one were built for ore wagons and mules, and it shows in the width and the hairpins. The climb from the Ouray side is steep and exposed in places, and the drop-offs are long. Oncoming vehicles require patience, with passing places few.
Weather is the real hazard. Afternoon thunderstorms are routine in summer, and lightning on a ridge is not a game. Snow can fall in any month, and the road is normally open only from around late June until October, depending on drifts. Start early, carry a layer, and turn back if the sky looks wrong. The air at this height is thin, so engines run weak, and you will feel it too. Altitude sickness is a real possibility for riders who go straight up from low ground.
There are no services at the pass. Ouray, about nine kilometres away as the crow flies but much further by road, has fuel, restaurants and motels, and Silverton and Lake City have the same on other sides of the loop. Fill up every time you can, and carry food and water, tools and a means of calling for help, though mobile coverage is poor. Respect the old buildings and mine sites, which are unstable and sometimes still dangerous, and pack out your rubbish.