The Postal Service's long-standing motto talks about enduring rain, sleet, snow and shine. An elite team within the Chicago Fire Department has grabbed hold of that motto — but they are delivering more than a telephone bill or the latest clothing store catalog.

As far as anyone can tell, the Chicago Fire Department is the only major city using a team of bicycle and Segway paramedics 365 days per year. During the workweek, the team patrols the city's business district, known as the Loop. On weekends, the paramedics ride along the Lake Michigan shoreline and the shopping district.

I asked CFD to let me saddle up and shadow the bicycle paramedics for a day. And although it has been a few years since I'd done much cycling, I assured CFD spokesman Will Knight that I could keep out of the way and keep up. Knight said I could ride along and that I'd have to keep up; the team would not wait for me.

Rather than have me chasing around through the congested city streets, it was decided that it would be better if I shadowed the paramedics during the Chicago Marathon on Oct. 7. It would be a course closed to traffic and a more controlled environment. CFD was to provide medical assistance to the spectators and serve as a backup for the private ambulance firm hired by the race organizer LaSalle Bank. But things don't always go as planned.

6:45 a.m.: With the sun still working its way up, I arrive at our meeting point, a fire station just blocks from Grant Park. The park serves as the marathon's start and finish area. I'm to ride with Dan Bomben and Sergio Moreno. In addition to working as a paramedic and firefighter, Bomben used to race cycles and worked as a bicycle mechanic. At the station, the six cyclists going out that day check tire pressure, tighten pedals, and inspect derailleurs and brakes. They all look like athletes.

The paramedics also fill the two pouches that hang from a rack over the rear wheel. Fully loaded, these pouches hold 30 pounds of medical supplies and equipment. Bomben says the added weight makes starting and stopping the bikes harder, but you don't notice it once you are going. The weather forecast for that day calls for unseasonably warm temperatures; its already 71°, the coolest it will be all day. Bomben says it's going to be a tough day for the runners.

7:20: We roll out of the fire station and through Grant Park, picking our way through runners and support staff to the find the medical command center.

Knight works in CFD's media affairs office. He's a tall, chiseled man who's an avid cyclist and a triathlete. When he learned that the city planned to put meter readers on bicycles, he asked why not do the same for paramedics. He won over Fire Commissioner Ray Orozco and the SERT program's bike team took to the road. SERT stands for Special Emergency Response Team. It started in June 2005 with two teams of first responders riding motorized Segways during the city's blues festival. The bike team first hit the streets in the summer of 2006 to provide advance life support for the city's food festival, known as the Taste of Chicago. By October, the Segway team was expanded to ALS and both units were sent out daily to patrol the business district.

7:30: The private ambulance firm hired by LaSalle Bank has two rows of ambulances lined up on a closed street that splits the park. As we wait for race organizers to bring radios, someone on the team says that it looks like they've got plenty of rigs. The guy who gives Bomben the radios warns the team to be careful around the water stations as the water and cups on the ground can make it hazardous for bikes.

Bomben, Moreno and I are Bike Team 3. Bomben and the others are not worried about the elite runners. They decide the best coverage is for one team to head up north about seven miles. The second team will cycle among the middle of the pack. When they reach the first team, lead team will chase the runners farther down the course. We will bring up the rear to keep an eye on the back of the pack. These runners are the most out of shape and are looking to finish the race in five to six hours; the winners finish in close to two hours.

8:00: The race starts. The temperature is 72°, but the humidity is at 78%. There are 45,000 runners, up 5,000 from 2006. Some reports say that 10,000 did not show up for the start, possibly due to the forecasted heat.

8:23: The event radios are not working. Bomben can't call out on his and the airwaves are filled event workers' chatter about what kind of computers they hope to buy. We go back to the medic tent/command center to get the radios replaced or fixed. With new radios, we head to the starting line.

8:34: Bomben offers encouragement to the runners we pass. He tells me that last year, the first year the team worked the marathon, he rode with this same slow group. There was an older man he was talking to and keeping and eye on. At the finish, the man thanked him for the support, saying he'd come alone from out of town and Bomben was the only one cheering him on. I ran this race in 2004, and fully understand how far a little encouragement goes — even from a complete stranger. Whether it is special events or a workday in the Loop, the SERT riders are to some degree the face of the city. People often will stop them to ask directions, these are mostly tourist looking for someone they can trust. When compiling this team, CFD had to find those who could handle they physical rigors of riding through Chicago's frozen winters and steaming summer, and those with excellent communication skills.

Larry Langford, CFD's director of pubic information, says the public reacts to the team similar to how they do the horse-mounted police. “People often like to get pictures taken with the crews,” he says. “They are a conversation starter.”

9:18: We hit water station number two just past the three-mile mark. The tables are being folded up and runners told they have run out of water and Gatorade. The temperature is already higher than 75° and climbing fast. The runners are livid. Many approach Bomben and demand to know why there's no water and what he will do about it. He says he'll radio the problem in. The event radio doesn't work; it won't work for the rest of the day. At water station three, just shy of six miles, there is little water and no Gatorade left. This does not look good.

We pass a Crystal Lake, Ill., firefighter who's walking in full turnout gear, SCBA tank and station boots. Bomben asks if he's OK. He says he is and that he's done this before. Later, I called his chief. The firefighter's name was Matt Thuma and he was OK; he completed 15 miles.

10:02: We find our first man down about 6.5 miles into the race. He's a 29-year-old who was overcome by heat and exhaustion. The temperature is at 79°. The historical mean average race day temperature is 59°. The hottest race day on record came in 1982 when temperatures reached 86°. That record would fall. Bomben calls for an ambulance on the race radio; no one answers. The man wants transport to an aid station to rest; his race is done. They take his vital signs and start him intravenously on a bag of saline. Bomben tries to keep the conversation with the guy light, but the ambulance is taking a long time.

10:17: Two of the private ambulance company's personnel are walking down a side street pushing a stretcher. They had to park two blocks away because the route was blocked. Bomben wants to know why they didn't dispatch an ambulance from the aid station behind us (where there would be no stream of runners to cross). They don't know.

Although the SERT riders most often works with CFD ambulances, being first on the scene is common. That, in fact, is a large reason for having the bike team. Being in the city and being able to negotiate traffic better than an ambulance, means they can treat patients sooner. In less than two years, they've already saved three lives; one was a woman in cardiac arrest.

10:25: A woman is down near where the ambulance parked. One bike team is already there, but Bomben and Moreno take over and send the other team back into the crowd. The temperature is nearing 82°. Bomben gives up on the event radio and uses his cell phone to call 911 for a CFD ambulance. “When the crap hits the fan, we take over and do it,” Bomben says. “The private ambulance companies just don't have the experience that we do.”

Crap is starting to hit the fan. Langford says it was around this time that the 911 calls began to spike and CFD took a more active role by running most of the communications out of the scene command post.

11:25: Near the 12-mile mark a CFD commander tells us that the Mutual Aid Box Alarm System has been pulled. The system includes more than 1,200 departments and extends to bordering states. This brings 10 ambulances from surrounding communities into Chicago to assist stricken runners. “We've taken this over,” Bomben says. MABAS has been used for several large-scale situations, such as the high-rise fire in, ironically, LaSalle Bank's building.

11:36: A man begins vomiting in the street behind us. He's heavy-set and probably in his 30s. Bomben and Moreno immediately start an IV and call for an ambulance. The guy is trembling all over.

11:37: A CFD ambulance arrives on the scene. It's 84° and the temperature has not yet leveled off. It is around this time that CFD, city officials and race organizers end the race. It is the first time in the marathon's 30 years that it has been cut short. In addition to bringing in more ambulances, the city dispatches busses to be used as cooling centers and to transport runners back to Grant Park.

11:58: We're at the halfway mark in the city's Greek Town neighborhood. Within the span of 15 minutes and one city block, Moreno and Bomben treat three runners — as soon as one is on his way, another goes down. I hold the IV bags so they can work faster. There's no doubt this is now an emergency.

1 p.m.: They are needed at the south medical center near mile marker 21. We ride along at a fast clip and I again think of getting left in their dust. Moreno rides behind me. My bike is about 15 years old, too heavy and largely neglected save for new tires and inner tubes installed two years ago. The SERT riders have mountain bikes with smooth road tires. They have beefed up sprockets and forks to handle the rigors of urban riding. Bomben says they bought the same bikes used by the police. But the police aren't lugging 30 pounds of medical equipment and supplies. They've learned that the heavy braking caused by the added weight is damaging the rims. To solve this they are retrofitting the bikes with disc brakes. The bikes, before the brake jobs, cost about $2,000 each. The program also has the added cost of medical equipment, which Langford puts at about $10,000 for the entire team.

1:11: Someone yells for paramedic. We find a 58-year-old woman who was losing consciousness while on a cooling bus waiting for ride to finish line. The temperature outside is 86°. She rebounds after one bag of saline and some oxygen.

1:30: We cut across the southern leg of the course through Chinatown to watch stragglers head north on Michigan Avenue back to Grant Park. Although the race was cancelled, many continued to walk and run the course. Organizers left the clock running and handed out medals to those who crossed the finish line.

1:55: We find a young man flat on his back 2H miles short of the finish line. It's still 86°, but will hit 88° by late afternoon. The man, Tim, wants to finish but is cramping and dehydrated. He takes two bags and is unsteady when we try to lift him to his feet. He reminds me of a boxer who wants to continue even when he can't see straight. A private ambulance arrives. Tim wants a ride to finish line, but the ambulance will only take him to a hospital. He refuses and accepts a police officer's offer to drive him to finish line. Later, I see Tim in the medical tent after the race; he's still a bit punch-drunk, but he got his medal for finishing and he's happy.

3:56: A call comes in for an address a half mile away. The three of us cut and weave through thick downtown traffic. The address turns out to be a subway station, where a CFD ambulance is already on scene. Paramedics bring out an older man, who looks to be homeless. This is the type of call the team typically responds to. On average, they get 65 calls per month; they had 780 for all of 2007. Of those calls, they were first on the scene 421 times.

4:30: The team calls it a day. Some of the guys race on the ride back to the fire station. Bomben says he's was disappointed because he hoped to ride the full 26.2 miles. And despite our cutting across the course, my odometer shows exactly 26 miles. But the real journey that day was moving from an event to an emergency. I can't say how many of the 65 calls the SERT riders answered during the Chicago Marathon were life-threatening. I suspect that most of those that I saw were not. Yet, there were some who left me wondering about what could have happened had the team not been there.