There are a lot of jokes circulating that a tandem bike is a divorce machine. There's also a popular saying: "Whichever direction your relationship is going, a tandem will get you there faster."

For Beth and Barton Cox of Makiki, tandem riding has made their marriage stronger. They spend about 30 hours a week "of wonderful togetherness," Barton said.

Their average weekly mileage is around 165, with Barton riding captain in the front and Beth as stoker in the back.

"Spending time together outdoors in the beauty of Hawai'i and enjoying our relationship is the big thing," he said.

The Coxes enjoy teaching other people to ride tandem. In fact, they offer first-timers a free loan of a tandem bike to help them get started. They are so passionate about the sport that they are convinced if more people try tandem cycling, they will get hooked.

They recently started an organization called Hawaii on Tandems (www.hawaiiontandems.com) that encourages, educates and organizes lessons and outings. There are now 10 tandem teams (couples) in the organization.

At last Sunday's outing of Hawaii on Tandems, Amber and Matthew Bailey of Kane'ohe turned up to give it a try.

"It's a chance to spend quality time together," Matthew Bailey said.

As a Marine, he does much of his physical training alone. "I think it would better help the communication in the marriage," he said. "We want to do something active together."

Nora and Mark Pillori of Kailua borrowed a tandem bike from Hawaii on Tandems and were immediately hooked.

"My husband is a really strong rider, and I could never keep up with him on individual bikes," Nora Pillori said. On tandem, however, "I've gotten stronger now and he can't get away without me."

COMPLETE TRUST

The Coxes recommend a couple trade off the captain and stoker seats so each has an understanding of what is involved. They employ little intercom systems for communication while pedaling.

While long-distance cycling is a lonely sport, tandem riding is an exercise in togetherness. For some people, it may be too much togetherness.

As the stoker, you have to place complete trust in your captain.

"In the back, you're like a passenger in an airplane," explained Frank Smith, owner of Island Triathlon & Bike and a tandem cyclist (with his wife, Laura) since 1979. "There's nothing you can do to control the airplane. If the person up front is bombing, it could be traumatic."

Smith does not recommend a tandem as a first bike purchase. It's important to have established biking skills before putting someone else on a seat behind you.

Stopping and starting can be the greatest challenge.

"It's a process," Smith explained. "You have to work out your own routine and stick to it. You have to coordinate the pedals. The stoker maintains a neutral attitude, and it can be hard if you're used to riding solo."

'LIKE A MARRIAGE'

The Smiths and the Coxes often take tandem bicycling breaks and vacations. The Smiths have cycled in Italy and completed part of the Lewis & Clark trail. During the August Admissions Day holiday next month, they will cycle from Kahului to Hana and spend two nights in Hana, then cycle back.

The Coxes recently returned from the Northwest Tandem Rally in Vancouver, British Columbia. They attended a rally on Kaua'i and plan to do the Century Ride on Sept. 20.

One weekend the Smiths and the Coxes rode from town to Turtle Bay and spent the night at Turtle Bay, then rode back.

"The thing that appeals to me most" about tandem cycling, Frank Smith said, "is that it's a great equalizer, in that each person can contribute according to his or her ability and you give back according to your need."

For newbies, "my opinion is that it probably accelerates the relationship in whichever direction it might be going. You'll have lots of good times and adventures, but if your relationship is stressed, I think it could aggravate it.

"It's a lot like a marriage — you have to communicate and cooperate and be sensitive to each other."

Barton Cox originally got started with tandem cycling to keep his weight down.

"I have fought high blood pressure since I was a preteen," he said. "I have been in Weight Watchers for four years and seven months now and, at age 66, I don't even take any high blood pressure medicine. I'm 6 feet 3 and weigh 177. I ride to eat.

"Beth just does it because she likes to be an athlete."