I seem to have this limit to my ability to climb at altitude

Somewhere between 7,200 and 8,000 feet my body seems to have an issue with with altitude when it comes to climbing on a bike.Today I dropped Chris off at the rink and headed out on my bike 15 minutes later. Today's route was an out and back up Big Cottonwood Canyon. From the mouth of the canyon its 12 miles to Solitude. Its actually a pretty comfortable ride, the grade is far shallower than that of Little Cottonwood, however, I seem to get to a point between 7200 and 8000 feet where my body has other ideas about progress.Steep pitches at this elevation seem to cause me to get light headed, shaky, and cause headaches when I attempt to climb them on my bike. I marvel at this because when hiking or skiing above this point it takes a bit longer for this to manifest. It must be a direct correlation to the level of exertion? Here are the stats;



Its Pioneer Day today in Utah, a state holiday that rivals the 4th of July in festivities.  The canyons were a bit busy with family picnics. This made traffic a bit of an issue at times and with each picnic area having its own fire ring, the burning of pinon, which I am so allergic to, made the air quality a bit hard to deal with today I returned home a bit exhausted!  

Hopefully tonight we will catch the BIG fireworks at Liberty Park with Andrew and his family.