Here it is the first Monday in August and I can check off another Pan-Mass Challenge from my list of accomplishments, although this time – my fifth – I have a different story to tell.

I’d probably rank my four previous PMCs among the best weekends of the year, if I could remember anything else that happened those years. Really, they were amazing rides.  I marked my first PMC and longest ride ever, at the time, crossing the finish line six months to the day after my father died from brain cancer. It doesn’t get much more poignant than that.

A couple of years later, I lost a close friend who I still miss dearly. He took me through the dunes in Truro that year. He carried me through some torturous back pain this year too.

But mostly this year I carried myself. Through my training season and through most of the 84 miles from Wellesley to Bourne, I rode alone. I enjoyed the scenery, I reflected, I endured, and I exhaled with relief when I crossed the finish line.

For those who don’t know about the PMC, I can’t imagine how you’ve missed it. With lifetime funds raised totaling $338 million, the PMC is the largest athletic fundraiser in the country. Founder Billy Starr has set a goal of $36 million this year. Every penny of the money raised goes to the Dana-Farber Cancer Institute.

More than 5,000 bicyclists ride any number of routes starting in either Wellesley or Sturbridge. Cyclists have all sorts of goals – and athletic achievement resonates in nearly every one of us – but most ride to honor someone: a loved one, or the loved one of someone we love.

I was hoping for 84 miles of bliss because, as you probably know, we cyclists are the happiest people in the world — after all, isn’t that what we say all the time? — but ecstasy wasn’t in store for me this year. What nearly ruined it for me this year was the behavior of my fellow cyclists.

PMC organizers are careful every year to remind cyclists that rules of the road are in effect during the ride. Roads – and lanes of traffic –are not closed for the ride.

Yet, cyclists behaved as if they’d never shared the road with another cyclist, let alone a motor vehicle. Road etiquette and safety tells cyclists to warn each other of cars approaching from the front or rear. And a cyclist who hears a “car back” warning always passes it forward so others know to move to the side of the road.

And, always, always, always, when it is safe, cyclists should move. They do not make the driver move into oncoming traffic.

Equally important, to avoid collisions, cyclists should always call their position if they are passing another rider. A simple “on your left” warns fellow cyclists that someone is approaching.

Yet I saw dangerous scenarios play out time and again. In fact, drivers were far more courteous than cyclists. It was as if the cyclists believed responsibility for safety applied only to motor vehicle drivers.

It is not my intention with these comments to devalue the contribution the PMC makes to society. I feel confident that Billy Starr does not want to see anyone injured. Most PMC cyclists are adults and we — not a charity — are responsible for our own behavior. But this is about more than responsibility; it’s about safety.

Billy Starr sent a well-deserved thank you email to volunteers and riders today, telling us how awesome we are for our accomplishments. I can’t argue with him there. But there are many others like me who felt nervous for their safety during their rides, and Starr would do us all a favor if he’d send an email admonishing riders as well.

Thirty-six million dollars becomes a much smaller achievement if someone dies trying to raise it.