First you hear the thump of approaching party music. Then a cry from a bullhorn: "Love that right lane, people!"

A loud chorus of energetic shouts: "BIKE PARTY! Yeah!" Ding ding ding go dozens of bike bells ... and a torrent of nearly 200 happy bikers begins to sweep past.

Many of the bikes are decorated with Christmas-style lights, in addition to conventional headlamps and tail lights. A few are pulling trailers with impressive portable sound systems. A couple of scraper bikes dart through the pack.

As the tide swells and continues, you can't help but notice that many of the riders are unnaturally pale - even greenish - with sunken eyes. Some have what appear to be gaping wounds and garish splashes of blood. Then you hear the hungry haunted groans, with an occasional plea: "Brrrraaaaaaiiiinnnnssss ... ."

This was the scene last Friday night when beginning at 8 p.m. at Frank Ogawa Plaza, nearly 200 people on bikes - many of them apparently undead - pedaled en masse across nearly 14 miles of Oakland streets and bike paths.

It was the sixth East Bay Bike Party - a fun monthly celebration of cycling, community and silliness that launched in May. This free, informal and all-volunteer-run event is modeled on the two-year-old San Jose Bike Party (which now averages about 2,000 people per ride). It's free, safety- and community-focused and family friendly.

Each month, the East Bay Bike Party chooses a theme and encourages participants to wear costumes and bring music or props that match the theme. This month, in honor of Halloween, the theme was zombies.

About half the riders dressed up (or down?) as zombies, or otherwise decorated themselves or their bikes. Prior months' themes included the Wild West, Superheroes and the 80s, among others.

Since this ride is about community positivity and safe cycling, participants must obey all traffic laws, including being considerate of cars on the road and stopping at traffic lights. Several volunteers helped orient riders to the route when the pack inevitably got split and stood watch at each turn in the route to direct riders.

Along the Route

After departing from Frank Ogawa Plaza near the 12th St. BART station, the zombie ride cruised down Broadway and then along Third St. into West Oakland, all the way to the Port of Oakland. There the ride was temporarily halted by a passing freight train blocking an intersection - and spurring many groans of "Trrrraaaaaiiiinnnsssss ... ."

But soon the horde of zombie riders proceeded onto the bike paths of Middle Harbor Shoreline Park. This park lacks nighttime path lighting, but the port's lights provided enough ambient glow to see the path easily. Fortunately, most of the bikes had their own headlights, and riders were careful not to cut each other off or stray from the path.

One of the most memorable points of the ride was the relaxed, impromptu party at the shoreline - with stunning views of the lit-up Bay Bridge and San Francisco skyline. The weather was just warm enough with a light breeze and people were dancing, talking, resting and enjoying a peaceful evening.

The bike party then backtracked through West Oakland to Jack London Square, where a lively round of bike sumo started. Organizers laid out a circle of red lighted cable about 20 feet across. Two bikers at a time would enter the circle. The rules: Keep your hands on the bars and your feet on the pedals and try to force the other rider out of the ring (non-violently).

The Jack London Square break was immense fun until the organizer with the bullhorn announced that, even though the operators of Jack London Square had invited the East Bay Bike Party back there, the security guards on duty wanted them to move along.

The pack proceeded back downtown, taking a circuitous route and earning many cheers from people on the streets and in cars. There was another rest break at an office building plaza along Grand Avenue, where many people danced to "Zombie" by Nigerian music legend Fela Kuti.

In its last stretch, the bike party rode around part of Lake Merritt, enjoying the Oakland skyline. The final destination was the Parkway Lounge on Park Blvd. and E. 19th Street. There, temporary bike racks were set up, and a vendor had an outdoor pizza oven going to serve snacks.

The ride took about three hours total and covered nearly 14 miles. Most riders did the entire ride, but some people dropped in late or dropped out early (especially people who brought kids on the ride).

Join the next East Bay Bike Party!

The date and theme are posted a few weeks in advance on the East Bay Bike Party blog, on their Facebook page.

On Twitter, follow ebbikeparty. There's also an e-mail list that includes event info and discussion of local biking issues.

To find out where there riders are while the bike party is happening (so you can join the fun in progress or cheer from the sidewalk), sign up for bike party text messages. Simply text ebbikeparty to 41411. Standard text messaging rates apply and messages are sent out only immediately before and a few times during the bike party.

Support the East Bay Bike Party. You can make a donation to cover expenses for organizing and running the event. You also can volunteer to help with the rides.

Tips for bike party riders:

• Bring water and a snack.
• Bring your headlight and tail light and extra batteries for them just in case.
• Stay in the right lane when riding. The goal is to share the road, not take it over.
• Wear layers and bring a rain jacket or windbreaker just in case.
• Costumes definitely help. They have started many conversations among strangers at the bike parties - and probably launched some new friendships.

For more info, e-mail ebbikeparty@gmail.com.

Zombie bike party route

<a href="http://www.mapmyride.com/ride/united-states/ca/-oakland/388128640067741851">October route</a><br/><a href="http://www.mapmyride.com/find-ride/united-states/ca/-oakland">Find more Bike Rides in Oakland, California</a>