Cross-Patterson Pass-Altamont Pass-Carroll-Flynn

Wednesday, January 17, 2018

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This route heads east across Livermore Valley for a hilly loop up Cross Rd to the wind farms around Patterson Pass and Altamont Pass. The return includes the additional climbs up Carroll and Flynn Rd N.

Begin this ride from the shopping plaza parking lot at the corner of S Livermore Ave and Pacific Ave in Livermore.

Head south on S Livermore Ave.

The road name changes to Tesla Rd as it turns eastward through the estate wineries and vineyards around Livermore Valley.

Enjoy the glorious valley views!

Cross Greenville Rd and continue east on Tesla Rd.

Turn left onto Cross Rd, it stretches 2.2 miles to its northern end at Patterson Pass Rd. The road climbs up from the valley floor past the scattered ranches for 1.7 miles with an average grade of 3%.

Enjoy the views!

At the left turn sign arrow, Cross Rd quickly descends followed by a short bump to the T-junction at Patterson Pass Rd.

Turn right, Patterson Pass begins to climb along the back ridge for the next 1.5 miles with gradient ranges of 7-11%.

The last bit up to the summit kicks up to steep grades of 12-15%!

On a clear day, the summit offers fabulous views of the wind farms lining the hillsides in the distance! The descent on Patterson Pass heading east to Midway Rd is fast! It winds down through the open grasslands with hilltop windmills.

The road rolls along the valley towards the Altamont Pass Wind Farm Substation to Midway Rd.

Midway Rd cuts across the valley for a short climb towards the windmills.

Midway drops down through the ranches before rolling underneath I-580 towards the California aqueduct off Grant Line Rd.

Lunch stop at the Mountain House Bar

Continue west on Grant Line Rd, it comes to a junction with Altamont Pass Rd.

Continue west on Altamont Pass Rd; it stretches 6.3 miles through the scenic Altamont windmill farms towards I-580.

The rolling terrain takes you past the Altamont Landfill to the summit at the Summit Garage.

The road drops downhill to Carroll Rd.

The climb up Carroll Rd is 0.8 mile with an average grade of 8.8% and steep pitches of 10-12%! The road levels out as you near the I-580 overpass to N Flynn Rd.

N Flynn Rd winds up through the hills at the far east end of Livermore; it climbs up around the Altamont windmills with gradient ranges of 4-6% for 1.4 miles.

The road name changes to S Flynn Rd as it rounds the bend towards the summit.

The road drops down into Livermore Valley from the hilltop ranch onto Patterson Pass Rd.

Patterson Pass Rd continues down across the valley into Livermore.

At Greenville Rd, Patterson Pass Rd continues west along the north side of Lawrence Livermore Nat’l Laboratory and Livermore’s Industrial Park area into the residential neighborhoods to N Mines Rd.

Turn left on N Mines for a quick jaunt through a residential neighborhood to East Ave followed by a turn on Dolores for the return to the shopping plaza parking lot.

This is a wonderful ride through the quiet less-traveled country back roads around Livermore Valley. Be prepared, check the weather forecast for dense fog and high winds and plan accordingly.

Garmin Stats:
34.52 Miles with 2772′ of elevation gain
Max elevation: 1178′
Max grade: 15%
Terrain: Hilly with steep climbs

Weather: Cloudy with dense fog. Cool temps ranging from the mid 40’s to the high 50’s with E winds.

View the interactive RGPS route map & profile

Follow this route for today’s ride:



  1. Thanks for the nice pictures Nancy. We’ll have to do this ride again when the sun is shining. I’m sure there was some nice scenery we missed because of the dense fog.


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