Sunday, March 6, 2011

Coastal Trail Runs: Montara State Park Half-Marathon

With the job I started back in late October, I've not been devoting much time or energy to training. Yesterday I got out for 50 miles on my bike, a ride cut short by a broken spoke on my Velomax wheel. Velomax wheels are designed with double-threaded spokes: one end threads into the nipple at the hub, the other end into a threaded hole in the hub flange (held there with Loctite). The idea is to avoid the stress-riser of a J-bend in the spoke at the flange side, supposedly improving spoke reliability. But this "theory" overlooks the fact a spoke can bend and rotate about a threadless flange hole, whereas with a threaded hole, the spoke end orientation is fixed, and any lateral pressure on the spoke will place a lot of strain on the spoke where it enters the hub, and since I take my bike onto the Caltrain bike car where bikes are stacked laterally, all it takes is someone's pedal in your wheel to supply lateral spoke force. Indeed, it is at the entry point of the flange where I've broken spokes on these wheels at least three times. Fortunately Freewheel Bikes in San Francisco can cut and thread a conventional spoke for me so I've been able to keep the wheel going.

Anyway, that was yesterday. Today I did the Coastal Trail Runs Montara State Park Half-Marathon. The route is all up and down: from San Pedro Valley Park we set off on a semi-loop, semi-out-and-back up to North Peak, then back to the start area for the "10 km" loop to the east.

The official course profile is here:


Here's my Strava data. Interestingly, shortly after beginning my descent from the North Peak the altitude froze in the mid-400 meter range. The Edge 500 relies on an air pressure sensor getting access to the ambient air, and if the holes, which are on the back of the unit get plugged with water, then the pressure gets stuck at what it was when the holes got plugged. Most of the run was in cool rain, and I was fairly wet. I had the Edge strapped onto my sleeve with a Forerunner wrist strap. This works nicely, but the plastic strap combined with the 2-ounce computer is uncomfortable on my skin, so I like to strap it around long sleeves if I'm wearing them. The wet clothing likely plugged the air holes.

DC Rainmaker photo
Garmin Edge 500 air holes, courtesy of DC Rainmaker


The run went well, considering how little training I've been doing. No acute pain, just fatigue. My biggest problem was descending from the North Peak, where the wet, rocky trail caused me to become very conservative about my footing with my light New Balance trail running shoes and a generally low level of confidence in my agility. In places I walked slower downhill than I'd climbed uphill earlier.

But even on the gentle, nontechnical downhills of the 10 km loop I was too slow. Toward the end of the race I passed Cara, who was hiking the 10 km event. She said I wasn't gliding like the fast runners, instead braking with each foot stroke. This is normally considered an issue with heel striking, but I try to keep my foot from getting ahead of my body, so don't think that's my problem. Rather I may simply be slamming my foot into the ground too hard. I don't know: I just need to practice more. Today was my first extended downhill running in a year.

The uphills I find easier. I don't really run them but rather do more of a power-walk. This seems to work really well. While guys like Gary Gellin or Leor Pantalot make me look like I'm standing still, I'm still competitive in these events on the climbs.

Cara, by the way, had a really good day. Her report is here. A few blisters but otherwise she did great given she's coming back from back and knee problems. We both agreed on the rainy day Coastal Trail Runs had gotten us outside when otherwise we'd have been huddling indoors waiting for the rain to subside.

2 comments:

said...

outside of simply handling the high impact forces well, I think running faster downhill necessitates lots of confidence in your ability to handle small perturbations in the foot - ground interaction. The fact that each strike might have more or less friction than you think makes for interesting coordination patterns. I would certainly go faster down a 15% grade if it were on a treadmill, or asphalt!

djconnel said...

I agree.... on gravel-covered paths, I'm afraid I'll hit a slippery patch and fall!