Observed Mountain Bike/Unicycle Trials (called "Trials" for short)
Observed mountain bike trials is a genre of bicycle riding dedicated to getting across obstacles. Picnic tables, benches, large spools, rails, walls, tires, blocks, boulders, ledges, even cars and roofs are all familiar trials objects. Competitions are laid out such that each rider navigates a tight course across the above-mentioned obstacles. The winner of the competition is the person who puts their feet on the ground the least. Not to be confused with BMX, trials is built on balance, timing, and precision, and leaves little or no impact on the terrain ridden.
As can be seen by the pictures, the UC Davis campus is an excellent playground for trials riders.
While the UC Davis campus is good place to learn moves, the sterile 90° ledges and perfect runups and runouts will not teach a trials rider the finer points of balance. So you need to find some rocks to play on. Davis has a few spots that are okay for riding trials and there are several more, including one world class venue, a short drive away.
Spots in Davis
The old Yolo County Landfill
This place is between the cart track and the paintball course in North Davis. Until recently it had a lot of busted up concrete and pavement scattered all over the place. It was a decent place to ride. They have recently started plowing stuff in semi-regularly. So it's hit and miss now.
Under the railroad bridge over Putah Creek
I'm talking about the bridge about 200 meters West of where Old Davis Road crosses Putah Creek. There is an assortment of rocks under the bridge that are plenty fun for riding. It can be under water in the winter, but summer it's nice because the bridge provides shade.
Theres a few other rocks here and there in Davis, but nothing that would entertain for more than an hour or so.
Rockville Hills Park in Fairfield
This MTB park suprisingly (ha!) has a lot of rocks that are good for riding trials. Lots of red basalt along the "rockgarden" trail that will entertain and challenge you for weeks on end. Theres a lot more there in addition to the rockgarden trail, you just need to do some exploring.
Cold Canyon (just below Monticello Dam)
DO NOT ride in the UC preserve! That is illegal. Ride in the area between putah creek and the road. Cold Creek (or whatever it's called) goes dry in the summer. That's good for trials riders because it's filled with a jumble of sandstone boulders. This is a very technical place to ride. It's also shaded in the evening by the surrounding hills so summer riding is managable. Park in the dirt lot on the right immediately after crossing putah creek (as you drive). Walk towards the dam and you'll see the streambed.
Beals Point at Folsom Lake
It costs 5-7 dollars to park here, but if you are clever, you can park in the neighborhood across the street and pedal in for free. This is the crown jewel of bike trials. There are gigantic granite fins and boulders all over the place. This is one of the best places to ride anywhere on the planet. I took a pro trials rider out here this past winter and when he saw the size and shape of granite and the bounty of the rocks, he peed his pants. I'm not kidding. The 2004 world champion unicycle trials rider lives in an adjacent neighborhood and rides here frequently. If you ride trials, you need to ride at Beals Point.
The mototrials park at Mammoth Bar was a lot of fun until they started charging 5 dollars to get in. I guess it's still fun, but I wouldn't know anymore. All sides of the river at the confluence area are filled with sharp and technical limestone. Lots of riding to be had here and the rivers to swin in in the summer.