I must always forget something major. Especially on long/remote/dangerous rides. I'll get deep into the technical canyon, 2 hours bike/4 hours hike from my car, and realize i left my water bottle in the car. Or drive 2 hours to a sweet trail i've been wanting to ride out in the boonies and realize i forgot my cell phone and gps. (cell phone doesn't matter much as most of those areas don't get reception).

On my last ride I was so proud of myself that I hadn't forgotten anything... it was 11 miles of probably the 2nd or 3rd most difficult singletrack i've ever been on. The whole ride went fine, a few minor wrecks and many brushes with nettles and blackberry bushes, but it was great. when I got back to the car I noticed my wallet was barely hanging in my back pocket. I forgot to put it in a zippered pocket or saddle bag. It was getting dark so if I had dropped it, it would be a bad day. Also my car/house/work keys were left in an open pocket as well.