Motorcycles and pets. A seemingly unusual combination, but come tomorrow, the two will come together for a good cause.

The Tulip Ride — an annual event now in its 15th year that benefits Seattle Humane — begins at 8 a.m. tomorrow at Blazing Bagels at 6975 176th Ave. N.E., Suite 365 in Redmond. The ride will take participants up north to the RoozenGaarde Tulip Farm in Mount Vernon, which is also a sponsor of the Skagit Valley Tulip Festival.

Jeff Henshaw, one of the founders of the Tulip Ride, said the ride started in 2001 when he and a group of his colleagues from Microsoft were working on the first Xbox console. He said things were getting pretty busy at work and so he and a few of his coworkers who also ride motorcycles decided to use one of their days off to ride together to the festival. The group decided to make this an annual ride and in the following years, they invited other riding friends from other area companies such as Boeing.

Within 3-4 years, Henshaw said they had hundreds of riders and began working with local police departments to help with intersection control as the groups rode through their towns. It was at this point that the group began thinking about using the ride as a way to raise money for a cause. Henshaw said it was a very organic process.

The beneficiary of the Tulip Ride has always been Seattle Humane as Henshaw said he and many of the original riders are animals’ rights activists and have adopted their pets from the organization.

“It’s actually a favorite charity,” Henshaw said about the group. “It was really just a personal passion.”

Aileen O’Connell, special events director for Seattle Humane, said they are an independent nonprofit whose mission is to promote the human-animal bond. The organization — which has actually been located in Bellevue since the 1970s — serves pets (mostly cats and dogs) in need and they have no time limits on how long an animal stays with them. O’Connell said they are able to do this through an extensive foster home system, adding that they have a 95-98-percent release rate and place about 7,000 animals in homes a year.

O’Connell said it has been great working with Henshaw and the rest of the Tulip Ride organizers and they are grateful for the support.

Last year, the Tulip Ride brought in about $50,000, which is the largest donation Seattle Humane has received from a grassroots fundraiser, she said.

The money raised from the Tulip Ride goes toward animal care. This includes housing, medical care, microchips, adoptions, spaying and neutering, community outreach, educational programs and pet training. O’Connell said the cost of care for each animal is about $595, so last year’s Tulip Ride funds covered about 84 animals.

The first year the riders considered raising funds — in 2004 — Henshaw said they just did it “pass-the-hat” style and people chipped in what they could. By 2006, they had a team of volunteers organizing things and formalized the process so people had to purchase tickets to participate in the ride.

In addition, the event has also come to feature celebrity guests who participants can meet, take photos with and get autographs from. This year’s celebrity guests are Katee Sackhoff and Tricia Helfer from “Battlestar Galactica,” Karl Urban from the latest “Star Trek” films and Bender from 106.1 KISS FM’s “The Bender & Molly Show.”

This year, $75 covers basic registration for one rider and one motorcycle. For those without bikes, a passenger ticket is $50. Tickets go up to $1,000 for VIP road captains, which Henshaw said they limit to 25. The latter ticket includes a full rider and motorcycle registration and a guided afternoon ride to a catered dinner with the celebrity guests after the ride.

In addition, there are “Just donate” and “Breakfast Only” options for those who cannot go on the ride. With the breakfast option, for $75, people can get photos and autographs with the celebs as well as a discounted bagel from Blazing Bagels.

People can register online at www.tulipride.org/register.php or they can show up tomorrow morning to sign up.

Henshaw said weather will have a big impact on what they are able to raise, so they are hoping for a nice day.

“We need Mother Nature to show up in full force,” he said.