Mt. Hamilton West Bike Climb - PJAMM Cycling

Mt. Hamilton West


The longer, more popular and easier of the two ascents in the East Bay up to Hamilton Observatory.

Explore this Climb

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Climb Summary

Cycling Mt. Hamilton West is the most popular bike climb in Santa Clara County

Ride 18.4 miles gaining 4,300’ at 4% average grade. 

Over 10,000 Strava members have climbed Hamilton as of April, 2020

Mt. Hamilton is the most popular bike climb in the South Bay and has been featured in more Tour of California races than any other climb (see Tour of California section below). On any given day, particularly weekdays, you are bound to see many cyclists on this very fun road bike climb. This is a Bay Area Top 10 Most Scenic Bike Ride

Final mile to the summit.

Mt. Hamilton from the west is also the longest climb in the Bay Area, by a good stretch over Napa County’s Mt. St. Helena (18.2 v. 11.5 miles).

Both sides of Mt. Hamilton end amidst University of California observatories.

Aerial drone view of the top of Lick Observatory

This is the more popular, but more gradual, of the two Mt. Hamilton climb segments.  According to Strava, as of May 2015, there had been 12,230 attempts by 5,017 riders up the west side while only 3,913 attempts by 1,979 riders from the east.   The grade throughout the climb is fairly mild, although the overall 4% average grade for the 18.3 mile climb is a bit deceiving, as there are 558’ of descent included in that average.  If we remove the 2.5 miles of descent (at an average -2.5%), the climb averages about 5%.  

Beginning of Mt. Hamilton West bicycle climb

Start climb in Alum Rock, east of San Jose.

As we begin our climb, we have many excellent views of Northern California’s San Jose and Silicon Valley to the west and southwest.  

Just about one mile up the climb, San Jose seen in the background.

Within a couple of miles we feel as though we have left civilization behind (as much as one can really do that 10 miles from the Silicon Valley) and are soon passing through grassy oak-studded fields.  The last six miles are up the mountain and through a series of switchbacks with a grade that increases to 5.7% on average for those final miles. Since the road was constructed between 1876 and 1887 with materials transported by horse and mule-drawn wagons, the grade could not be too steep, hence the many switchbacks and turns up the six mile ascent.  It is reported that there are approximately 365 turns on the roadway -- see Wikipedia-Lick Observatory for an excellent history of the Lick Observatory and Mt. Hamilton West.

Mt. Hamilton West generally consists of three separate climbs:

  • Climb 1: Ride 5.9 miles gaining 1,499’ at 5%. This segment ends at the beginning of the first of two descents on the route (this descent is 1.8 miles, dropping 315’ at -3.2% average and ends at Joseph D. Grant County Park - Grant Lake).

Cycling Mt. Hamilton  - cyclists on bike on road with San Jose and Silicon Valley in background

Views of San Jose along the first few miles of Climb 1.

Bike climb Mt. Hamilton  - cycling on bike riding on road with hillside and grazing cows in background.

Grazing land for much of the second half of Climb 1.

Bicycle ride Mt. Hamilton  - cyclist descending through trees

Climb 1 is followed by a 1.8 mile descent.

  •  Climb 2:  Ride three miles gaining 740’ at 5% followed by a one mile -3.8% descent of 203’.

Climbing Mt. Hamilton  by bike - cyclist on bike on road riding between oak trees.

It’s all about the oaks on Climb 2.

  • Climb 3:  Ride 6.3 miles gaining 1,970’ at 6% ending at the Lick Observatory.  This is where we encounter one of the most winding stretches of roadway in California (maybe the “whinediest” if you’re not prepared for this challenging climb).

Bike climb Mt. Hamilton  West - start of second climb - Hwy 130 road sign

Start of Climb 3.

Two miles from the top, looking west-northwest.  San Jose and Santa Clara in the background.

Mt. Umunhum is visible as we climb the final segment of Mt. Hamilton West.

The summit for the Mt. Hamilton West climb is the Lick Observatory, owned and operated by the University of California, this is the world’s first permanently occupied mountain-top observatory (the sign on the first building we come to at the top says “Residents Dining Hall” -- inactive as of 2015).

Biking Mt. Hamilton West - Lick Observatory entrance. Cyclist riding past front of Lick Observatory.

Lick Observatory at the top of the climb.

   Dome of the Lick Observatory after Mt. Hamilton bike bicycle ride.

View northwest.

Roadway Surface and Traffic Report:  The roadway surface is excellent and the traffic is mild to moderate, depending on the time of the week.  Of course, weekends are busier as there are exceptional views from the observatory, which is open to the public from Thursdays through Sundays noon to 5 p.m. (as of May 2015).  

Mt. Hamilton is in the Diablo Mountain Range.  It is reported that on clear days one can see the Santa Cruz Mountains, Monterey Bay, and Yosemite National Park (see, Wikipedia - Mt. Hamilton).  Unfortunately, on two of our times up Mt. Hamilton we were in the clouds much of the trip, and on the other we were suffering at about the halfway point of the Devil Mountain Double (not a time to truly relax and enjoy the views!).


Mt. Hamilton is the most featured mountain climb in the history of the Tour of California, having been featured six times between 2006-2019.  Mt. Hamilton has never been a mountain-top finish in the ToC. (Note that ToC is on hiatus for 2020.)

  • 2008 Stage 3:
  • Queen Stage - Modesto - San Jose
  • 102.7 mile, 8,039’; eastern approach
  • Stage winner Robert Gesink (NED)
  • 2011 Stage 4:
  • Livermore to San Jose
  • 81.8 miles, 8,337’; eastern approach
  • Chris Horner (USA)
  • 2014 Stage 3:
  • San Jose to Mount Diablo
  • 107 miles, 10,574’; western approach
  • Lawson Craddock (USA)
  • 2015 Stage 3:
  •  East San Jose - San Jose
  • 105.5 miles  10,200’; eastern approach
  • Toms Skujiņš (LAT)
  • 2017  Stage 2:
  • Modesto to San Jose
  • 89.8 miles, 8,064; eastern approach
  • Rafal Majka (POL)
  • 2019 Stage 3:
  • East Stockton to Morgan Hill
  • 128.6 miles; eastern approach.
  •  Rémi Cavagna (FRA)

2019 Stage 3 Profile: May 14, 2019, 128 miles / elevation gain 9,667’

Peloton makes its way up Mt Hamilton West -- 2014 Stage 3.


Beginning of Mt. Hamilton West bicycle climb

Sunset from Lick Observatory.

Cycling Mt. Hamilton - Lick Observatory aerial drone photo at sunset

Truly a sight to behold.