Today along with my normal grocery haul, I added two propane tanks to the load on my cargo bike.  I was happy that they fit nicely in my saddle bags along with several bags of groceries.  The Hammer Truck continues to impress me with its versatility in this respect.

My wife was a little concerned when she saw what I was planning to do.  “Please be extra careful,” she said.  “Those tanks will be like bombs if you get hit.”

Since I haven’t had any close calls on this bike, I wasn’t worried.  The propane tanks weigh 17 pounds each, but I regularly ride with both my son and daughter on the back of the bike (downhill only… going uphill with that much weight is beyond my ability, even with the motor).  And with my kids on it, even though the center of gravity is higher, the bike still feels stable.

But today when I reached a steep downhill and was coasting at about 30 miles per hour, the bike began to oscillate side to side.  Each oscillation got stronger and stronger, and I had to slam on the brakes to avoid losing control.  I wasn’t sure what was causing the oscillation, but I figured it had something to do with the tanks.

Sure enough, when I got home and shook the tanks, I discovered that they are not full.  There is plenty of room for the liquid inside to slosh around.  The sloshing must have synchronized between both tanks.  Having 30 pounds of liquid moving back and forth at that speed is hair-raising, to say the least!  Afterwards, I kept my speed under 20 miles per hour, and I had no further problems.

In the future, propane tank transport will likely be one of the errands I save for the car.