Although it's still possible today to occasionally spot a couple enjoying an outing on their tandem, or "bicycle built for two," this bike was really the rage back in the 1890s. Now, the U.S. Postal Service is honoring the tandem bicycle on a new 24.1-cent stamp.

The denomination of 24.1 cents is for unpresorted ZIP plus 4 mail and is used principally by midsize businesses.The design is based on a Smithsonian Institution photo of a Columbia Model No. 43 tandem. The actual bicycle is on display at the Smithsonian. At the top of the stamp is "Tandem Bicycle 1890s" and at the right is "24.1 USA." Beneath the riderless bicycle at the left is "ZIP 4."

First-day cancellations are available in the usual two methods. You may buy the stamp at your local post office and affix to your own envelope. Remember, however, that at least 0.9 cents additional postage must be affixed to meet the minimum first-class rate for letters. Send to: Customer-Affixed Envelopes, Tandem Bicycle Stamp, Postmaster, Redmond, WA 98052-9991. Requests must be postmarked by Nov. 25. No remittance is necessary.

If you would rather have the Postal Service affix the stamp, enclose a personal check or money order for 25 cents per cover. The Postal Service will affix one 1-cent Omnibus stamp. Send to: Tandem Bicycle Stamp, Postmaster, Remond, WA 98052-9992. The deadline is Nov. 25.

According to the Postal Service, Redmond was selected as the site for first-day ceremonies because that city has been called "The Bicycle Capital of the Northwest."

The new "Special Occasions" stamp booklet is expected to be a popular item in post offices throughout the country, and the Postal Service is geared up for big sales.

The booklet focuses on the four most requested messages: "Happy Birthday," "Best Wishes," "Thinking of You," and "Love You." New York artist Harry Zelenko developed the colorful, stylized designs for each theme, as well as the artwork for the new edition.

The booklet is designed in such a way that it allows mailers to pick the stamp bearing the appropriate message and easily remove it without disconnecting the others. Inside are two panes of six commemorative-size stamps, each folded through a center gutter to create four subject "pages" of three stamps each. "Thinking of You" and "Love You" make up one pane, while "Happy Birthday' and "Best Wishes" make up the other.

Collectors of first-day covers may buy a random single stamp or specific six-stamp panes. Here's how to order:

You may buy the stamps at your local post office and affix them to your own envelope. When addressing the envelope be certain to allow plenty of room for the stamps you are placing on it. Send to: Customer-Affixed Envelopes, Special Occasions Stamps, King of Prussia, PA 19406-9991. The deadline is Nov. 21. No remittance is required.

For Postal Service affixing, enclose a money-order or personal check for 25 cents per stamp or $1.50 per booklet pane. Individual stamps will be affixed at random, and requests for specific single stamps will not be honored. You may request specific full panes and must include one cover for each pane ordered. The two pane combinations are "Thinking of You,"- "Love You," and "Happy Birthday"-"Best Wishes." Mail to: Special Occasions Stamps, Postmaster, King of Prussia, PA 19406-9992. It must be postmarked by Nov. 21.