Routes from Hygiene Short and relatively easy route to Carter Lake Dam and back. The purple door loop is the perfect midweek training loop close to both Longmont and Boulder. A loopy route from Hygiene to Masonville, lots of rollers with no significant climbing...a perfectly-mellow day in the saddle! Start in Hygiene and roll through CR23 and country roads through Masonville. Then climb the rollers along horse tooth on the way through Bellevue and over the long gradual climb of Rist Canyon. Riders are then rewarded with a long rollout back to Masonville before returning via backroads to Hygiene. This is the century version of the Hygiene to Rist ride.