Sunday, March 18, 2012

Trip Report: Using GPS biking Mt. Diablo

This post launches a new category at GPS Tracklog — Trip Reports. The point isn’t to provide a trail guide, but rather to exhibit some of the ways to utilize your GPS. This report focuses on a circumnavigation of Mt. Diablo, a 3849′ peak that dominates the eastern side of the San Francisco Bay region.

My wife and I were in the area this past week doing GPS mapping demos, promoting my book, GPS Mapping – Make Your Own Maps. Since our days were open, we decided to get in a mid-week bike ride.  Living on California’s heat-deprived North Coast, we opted for a ride slightly inland. Mt. Diablo was our target, and since I didn’t know the area very well, I turned to a message board on for help. I wasn’t disappointed. Several people, especially EBrider helped out, designing an awesome loop that incorporated technical single track, loose and steep fire roads, and nearly 2,000′ of elevation gain.

EB sent me a track in the form of a .tpo file, which is a National Geographic TOPO! (Amazon link) file format. This, combined with the trail descriptions provided by EB and others at, gave me almost enough info to plan the trip, though I will admit to picking up a hard copy of a trail map so that I had good access to trail names and other features. Too bad the Mount Diablo Interpretive Association doesn’t have this map posted online. Online trail maps (often PDFs), combined with mapping software and aerial photos, are typically adequate for my purposes.

I took the track that EB sent and exported it from TOPO via my GPS (a real pain since TOPO makes you convert tracks to routes in order to export them). I then imported it into TopoFusion, which allowed me to see the track on a color aerial photo. USGS posts color urban aerial imagery for major US metropolitan regions online at TerraServer, with more locations being added on a frequent basis. These images are readily available in programs like TopoFusion and USAPhotoMaps, which add a better user interface and allow you to transfer data to and from your GPS. The color imagery extends into natural areas in many cases, and the detail is amazing, going down to 0.25 meters per pixel. Notice the waypoint (MDNPEAKTR) in the image at the right. Mt_diablo_2 You can see a fire road going off to the north from the waypoint and, while the online image isn’t as sharp as the original, you can actually make out single-track going off to the northeast!  The single-track leaves the image near the top of the right-side.

With TopoFusion, I traced the single-track as accurately as possible, and created waypoints for major trail junctions. I then loaded the waypoints and redrawn track to my GPS, making the track blue so that I could clearly distinguish it from the tracklog being created as I rode.
The only things left were to create a route to guide me from waypoint to waypoint, and generate a printed map. I’ve posted the ride at 4 meters per pixel (black & white) using TopoFusion’s PhotoFusion feature, which apparently doesn’t yet allow access to the color aerial imagery when using their HTML Image Map feature.

EDIT: I asked at the TopoFusion message board and found out that you can capture a color aerial .jpg and replace the one generated by TopoFusion. My Mt. Diablo PhotoFusion page now shows the color aerial at 4 meters/pixel..

If you want to to learn more about how to use GPS and mapping software, check out my book. It has chapters on National Geographic TOPO!, USA PhotoMaps and TopoFusion. And for those of you who want to know more about the ride itself, read on…

At the North Gate Station, a ranger reiterated the warning we had heard about steep dropoffs on the North
Peak Trail, and the loose and steep fire road down from Prospectors Gap. We parked and started out on pavement at Juniper Camp, with the best photo of the day being taken shortly after starting out.

I had asked the guys at the NorCal forum for a ride that didn’t exceed 2,000′ of gain. We typially ride fire roads, rarely venturing on pavement; if I had realized how much easier the climb was going to be on asphalt, I might have asked for something with a little more gain. The North Peak single-track was a little intimidating, because we aren’t used to riding technical single-track and we didn’t know the trail. I think we could have cleaned most of it if we had ridden it previously. It was great fun though–we really wanted to go back and ride that section again.

The steep and loose fire road, on the other hand, wasn’t a problem at all, probably because we often ride logging roads with similar characteristics. The remainder of the ride went by Murchio Gap and Deer Flat before returning to our starting point. According to the barometric altimeter on my Garmin 60CS, the ride totalled 1677′ of elevation gain, and was 6.58 miles in length.

About Rich Owings

Rich is the owner, editor and chief bottle-washer for GPS Tracklog. Connect with him on Twitter, Facebook or Google Plus.


  1. Linda R.Sampietro says:

    I just read this with interest and smiled. Long before asphalt roads or fire trails, I lived in Walnut Creek. In the years between 1957 and 1959 my brothers and friends and I used to climb all over Mt. Diablo-If you can believe it, because it is true, one day my girlfriend and I climbed to the top!! More interesting than the view is the fact that while digging around in the new spring grass, I found many,many seashells,much to my surprise. This was just one of our adventures. My brothers and I used to ride our bikes as far back as we could to the south of our housing tract. Then we would walk back about 5 miles or so. We had our snake bite kit, water and some food. We would spend the day in our own wonderland. Sometimes we would climb up hills and look far down the other side onto a ranchers homestead, the cattle looked like ants, or at least like our toys. I suppose I should write my own book. Linda….P.S. Back in the day, one kid put cardboard under himself and rode down the opposite hill. Some kids used round metal disks. Anyway, somebody caught the hill on fire!! Another true-who’s in the “hot seat” story. We also used to spend the summer day catching and releasing tiny frogs at the manmade lake in Lakewood, the housing area just to the immediate Northwest of our housing tract. One bit of news sure to make some cringe: My parent paid just under $16,000.00 for their 3/2 home.!!! Kind of makes you sick doesn’t it. We lived in the 700 Block of Russel Drive. Very fond memories.

  2. Great memories! Sounds like you have an explorer’s spirit. I love the fire story — guess it just takes a spark.

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