Walnut Creek Metropolitan Park
Walnut Creek Metro is Austin's most popular mountain bike course, in part because it is the easiest course of any significant length in town. Also, because of its location near I-35 and Parmer, near the heart of the Austin tech center, Walnut is a convenient place for after-work rides.
To be clear, saying that Walnut is the easiest mountain bike course in Austin is like saying that the Northeast Ridge is the easiest route up Mt. Everest. Everything's relative. Beginners will find most of the course accessible and will be able to ride enough of it that they don't get frustrated, but to clean everything at Walnut will require advanced skill. Most of the trails are smooth, flowy dirt track with some banked turns, roots, mostly non-technical creek drops, and other features typical of Blackland Prairie trails like Bluff Creek, but Walnut also has a few sections, particularly on the south side of the creek, that pick up more typical Hill Country limestone features.
All of the trails at Walnut Creek are bi-directional, but mountain bikers most often ride the course counter-clockwise from the pool parking lot (the first lot on the left as you enter the park from Lamar Blvd. Marked "START/END" on the map above.) In 2008, the Austin Ridge Riders added signage at major trail intersections which points out the direction of the intermediate loop (look for the arrows with blue squares inside them) as well as the way back to the parking lot and the intersection number (to be given to 911 in case of emergency.) The blue dotted line on the map also indicates the "standard" intermediate loop.
Walnut Creek typically takes a while to dry out after a heavy rain. The flat parts of Point Six, Log Loops, Mark's Art, and Windy Loop are typically the last sections to dry, since they are tree-covered.
It should be possible for intermediate riders to ride the entire course in the middle chainring, and in fact, this is recommended (granny gear doesn't have as much torque and will cause you to spin out on a lot of the climbs.)
Starting out northwest at Intersection 238, you ride over a non-technical, swoopy berm near 262. The trail veers right at 262 and follows a fence before making an intermediate-level creek crossing (Rock Bridge.) Be in a low gear or the ascent out the other side will stop you. Turning right at 306, then left at 308 puts you on the Point Six Loop, a non-technical dirt track through the trees which has a lot of tight turns on which you can practice cornering skills. Point Six dumps you out at 310. Veer left, then left again at 312 onto Tangle Wild. Tangle Wild follows a powerline road for about 100 yards before veering right onto a narrower (but still relatively wide and non-technical) singletrack.
Soon after veering off the powerline road, there is a short, very steep, optional drop at 314 that loops back around to join the Tangle Wild Trail after about 100 feet. This drop used to be smooth dirt but has become eroded as of this writing and is a bit sketchy near the top. This, and other steep drops at Walnut, are marked black diamond not because they require advanced skill to clean but because the consequences of failure are somewhat dire. Some beginners have been seriously injured (broken backs, etc.) from losing control on one of the black diamond drops at Walnut, and in general, these obstacles should not be attempted by those who are new to the sport. However, intermediate-level riders ride all of them (with the exception of the Root Drop) on a regular basis.
Continue on Tangle Wild down to 302 and veer right. This takes you down to the Root Drop, a double black diamond descent into Walnut Creek. The original line (to the right next to the tree) used to be perfectly rideable, believe it or not, but extensive erosion has exposed huge roots and rendered it impassable to any mere mortals (I have heard rumors of some billygoats that can clean it.) The new line, farther to the left as you're facing the creek, is a very steep dirt drop with a lip right near the bottom, perfectly positioned to launch you face down into the creek if you get too much speed. It used to be a single black diamond line, but a flood in late 2009 exposed some roots and cranked it up a notch. At least one rider is known to have been seriously injured here (broken collar bone) since the flood re-arranged it. Use extreme caution.
Assuming you're enough of a badass to clean the drop, pop up the short ledge on the other side of the creek and ride out over the roots to your left. Otherwise, walk your bike across, downshift, and remount on the limestone shelf to give yourself a head start for the rooty ascent. Bear right and up a second, smooth ascent to 420. Turn right here onto the non-technical Shady Springs Trail. Follow Shady Springs down to 450 and veer left, then turn right at 446 to pick up an optional short technical loop. This loop makes a ledgy, intermediate-level drop down into a creekbed and then a rooty climb back out to 444.
At 442, turn right and head down Powerline Hill, a moderate but beginner-friendly creek drop and ascent to 506. At 506, the intermediate loop continues left and down the rest of Powerline Hill, but going straight takes you to the Endo Valley black diamond loop. This is a true black diamond drop and ascent. The drop is very steep, ledgy, and rooty, and it requires a tight turn halfway down to avoid a sharp outcropping of rock. Once at the bottom, Endo Valley follows along a smooth creekside trail for about 100 yards before making a moderately steep and ledgy ascent back up to 510. Ah, but you're not done yet. Now comes the fun part. The steep ascent from 510 up to 508 is the essence of Hill Country ledgework. Even advanced riders may find this difficult to clean consistently. Use the second-to-lowest gear in the middle ring and keep your eyes glued to the top of the hill.
Back at 506 again, rejoin the intermediate loop down the fast dirt track of Powerline Hill. This descent is all smooth, but be careful of the eroded spots, which will cause you to lose control if you hit them too fast. Making the sharp left at the bottom of Powerline Hill, you enter a moderately technical rooty section and a banked turn down to a moderately technical, ledgy creek crossing (Waterfall Crossing.) Climb up the other side and keep going straight to enter the Log Loops.
The Log Loops are mostly non-technical dirt track with some roots, a lot of tight turns, and some short, relatively shallow climbs and drops. Follow the signs, and you should end up at 606 after riding both loops. Go straight through the intersection at 602/604 and grab a low gear for the rocky ascent up onto the Detention Dam. Ride across the dam and pick up speed for the ascent up the steep limestone slope on the other side. Bear left at the top of the slope and onto the trail, then make the sharp right-hand banked turn at 504 onto Powerline Hill West. There is a surprise steep creek drop about halfway down this trail. It's not as steep as, for instance, the one off of Tangle Wild, but it is more rocky and loose. Be ready for it.
Go straight at 441 and ride the fenceline for a couple of hundred feet until the trail jogs into the woods. This is Mark's Art, a trail which mostly zig-zags through a series of moderate creek drops. Some of these drops have been lined with paving stones. Mark's Art culminates in a difficult obstacle, a sharp right-hand turn followed by a log pyramid with a steep downhill on the other side of it. This pyramid, taken in isolation, would be easy, but it's difficult to get up enough speed with the sharp turn to avoid high centering on it. High centering or clipping a pedal on the peak of the pyramid is a sure-fire recipe for sending you down the hill without your bike.
Follow the blue dots onto Tangle of Trails. The Tangle of Trails is moderately technical, with more of the same roots, banked turns, small ledge features, etc., but it also has a lot of climbing and some nice downhills. The Tangle of Trails dumps you out at 414. From there, the intermediate loop continues right, but more experienced riders can take in an additional technical loop by making the hairpin right turn onto the trail that leads up to 412. This climb is the longest in the park and is mostly non-technical, save for a few short ledges. At 412, cut over to 400 and drop back down the hill again. Right after the trail split rejoins, look out for a sharp 2-foot ledge drop. If you can control your speed enough on the hill, make the screaming right-hand turn at 403, since this takes you onto a fun high-banked turn at 402. Otherwise, you can just keep going down the hill and take a left at the bottom. In either case, take a right at 404 to get to the Main Creek Crossing.
The Main Creek Crossing has a small ledge that you'll have to pop up onto and a moderately steep dirt climb out the other side. Don't go straight across the creek but instead look for the trail exiting to the right. This is the intermediate loop. Follow the singletrack as it steadily climbs up and joins the Service Road doubletrack at 226. Follow the Service Road for a short distance before veering right onto another singletrack at 218. Riders desiring more of a challenge can turn right at 220 and onto the Severe Consequences Loop. This loop starts out easy, but right after the hairpin turn, the trail follows very close to the edge of a sheer cliff (hence the name.) It then makes a very ledgy, technical descent into the creek bottom, followed by a hairpin turn, followed by a rooty climb back out. This descent is tricky but not nearly as technical as Endo Valley. Turn right at 222 and complete the rest of the (mostly non-technical) loop back to 212.
At 212, you veer right onto a trail that parallels the service road. At 208, those desiring more of a challenge can make the steep, rocky, and somewhat sketchy drop to the right and follow the singletrack back up to 202. The rest of the singletrack after the drop is easy. Those desiring less of a challenge can veer left back onto the service road.
Following the service road back to the main park road, turn right along the sidewalk and follow it to the entrance of the Windy Loop. Windy Loop is typically ridden counter-clockwise, but riding it clockwise is much easier. In the counter-clockwise direction, get ready for a steep, ledgy climb at 104 with a dogleg right halfway up. There is an active spring here which, when flowing, makes it almost impossible to get traction on the limestone. Another long, steep, climb is at 100. This one has some big roots, and the dirt is often loose. Advanced skill may be required to clean both of these climbs with any amount of consistency. Use the second-to-lowest gear on the middle chainring for both of them, and keep your eyes glued to the top of the hill. The rest of the Windy Loop consists of some tight turns and a lot of roots.
Exiting the Windy Loop, cross the road onto the BMX Loop, a 1-mile bonus loop that consists of banked turns, jumps, and other BMX-style features. This loop also has some short, rocky climbs, and a series of three "whoop-de-dos" (smooth creek drops that flow from one to the next) near 114. After the second whoop-de-do, watch out for the low-hanging tree. After the last whoop-de-do, make a left at 114 into the BMX park. Less technical riders will want to turn left at 112 and go around the sharp hill. Those desiring more of a challenge, make the short drop at 113 and pick up as much speed as you can to ascend the sharp knoll at the other side of the BMX park. Then be ready for an equally sharp descent down the other side. The trail then makes a moderately rocky ascent back up to the park road.