JERUSALEM, Jan. 3 (JTA) — With helmets and gloves strapped on, water bottles filled, the 40 cyclists on Birthright Israel put their bikes in first gear and set out on the 18-mile ascent to Jerusalem. They rode unpaved, gravelly roads past cypress and olive trees, stopping to pick and gnaw on pieces of carob. Muscles burning and breath coming in short bursts, they climbed steep hills, with some opting to walk their bikes up instead. At the end, they were elated to have finished the ride. "It was incredible," said Loren Freedman, 21, a student at the University of California at Santa Barbara. "I love riding a bike, and exercise really clears my mind, allows me to really see and learn about this place." That´s how most participants on Birthright Israel By Bike! Challenge feel about this program, chosen from among 30 different options offered by Birthright, which offers free, 10-day trips to Israel for Jews ages 18 to 26. These are tourists who don´t want to travel around Israel by bus, even if it is their first time seeing the Western Wall, climbing Masada or floating on the Dead Sea. "I really didn´t want to sit on a bus for 10 days," said Noah Spector, 21, from Ottawa, Canada, who runs a mountain biking program at a summer camp. "But I always wanted to come to Israel, so a bike trip was an added bonus." Touring Israel off the beaten track is clearly a different type of tourism. Israel By Bike! was created by Avi Green, a 25-year-old entrepreneur living in Chicago. A lover of cycling and the Middle East, he proposed the mountain biking trip to Israel Experience Educational Initiatives, an organization that creates several specialized programs for Birthright. The plan was to offer an eco-adventure for young Jews who wanted to get a glimpse of Israel, but not in the standard way. The participants spend five of their 10 days cycling around the country, as well as hiking and rappeling. Along the way, they see the standard Birthright sites, including the Western Wall, Masada, Yad Vashem, the Knesset and Supreme Court. "We did some pretty inventive marketing," said Green, who works as a business consultant. "We even placed an ad in Outdoor Magazine." During the initial registration, 296 people planned to participate in the bike trip this winter. When it came time to pay the $200 registration fee, the numbers fell to about 240, Green said. Later, when a series of suicide bombings in early December claimed 26 victims in Jerusalem and Haifa, the number of participants dropped to 110. While the security situation scared away many prospective participants, Birthright officials are still pleased that 6,000 Jews will have participated in this winter´s programs, some 3,500 of them from North America. "Considering the situation, we´re not doing too badly," a Birthright spokesman said. Some 24,000 youth have gone on Birthright trips since the program began in late 1999, 14,000 of them in 2001. Officials are hoping that 18,000 will participate in 2002. According to initial figures gathered in 1998, the five-year plan estimated a total of 93,887 participants through 2004. Despite some apprehensions about the security situation, 37 participants for the first leg of Israel By Bike! — the rest will come in January and February — boarded a plane for Israel, some with bicycle seats and pedals tucked in their suitcases. Some of this week´s participants were serious cyclists, taking part in races and rides around the world. Others just looked the part, including New Yorker Moshe Rubinstein, who was wearing a red-and-white polka dot spandex biking shirt and shorts that he purchased from auction Web site eBay.com. "Spandex is the big joke in the group," said Green, referring to the shiny, stretchy fabric often worn by serious runners and cyclists to absorb sweat. Only a few participants actually shipped their own bicycles; most just brought some creature comforts, as well as helmets, gloves, pedals and comfortable biking gear. There also were more than a few beginners, whose only experience with cycling was down the paved streets of their hometowns and cities. Yelena Sukhodrev, a Brooklyn College student, rides a bicycle regularly, but usually down Ocean Parkway. She kept a slow but steady pace at the back of the slower group during the Jerusalem ride. Natasha Goets, a Chicago native, was surprised at how hard it was to log six miles on unpaved tracks, compared to her usual 12-mile circuit at the University of Illinois. She, too, took it slow on the downhills. Others put in some time training before the trip. Laura Kaplan, 25, of Fairfax, Va., took spinning classes for three months, hoping the intensive exercise from hopping on and off a stationary bicycle would help. It helped, she said, munching on canned stuffed grape leaves after finishing a day´s five-hour ride. She´s also quite satisfied with the group. "This was my top choice and it´s an awesome group," said Kaplan, who wants to see Israel without religious influences. "I just want to talk to folks, understand the politics and enjoy the people I´m with." The mix of ages and backgrounds on the biking trip was unusual for a Birthright group, Green said. About half are in college, while the other half fall between the ages of 22 and 26. Rubinstein, 24, a Lubavitch Jew from Brooklyn´s Crown Heights isn´t a stereotypical eco-applicant for Israel By Bike! But he is the right age, and had never attended a peer group trip to Israel, even though he has been to the Jewish state before. "I felt I had to come back at this time to give strength to Israel as things escalate," said Rubinstein, who has been traveling the world since attending rabbinic college in Australia. "I was kind of apprehensive to be the religious Jew in the group, but it´s been great to be with these people," he said. "There are no cliques here; we´re all individuals. I don´t feel like I´m taking anyone´s seat."