Aztec:
One tough ride is not chronic overtraining, but it is the start of it if insufficient recovery and additional stress factors are present like weights and insufficient sleep.
Riding and lifting tax your bodies recovery a lot. Only getting 7 hours is not enough. I'll bet if you took 1-2 weeks off the squats, you would increse your pounds/reps from what you are doing currently, especially if you are lifting higher poundages.
The bigger/stronger your legs are the more waste they generate. Unfortunately, the kidneys do not increase in size or in filtering efficiency as you get bigger/stronger.
When you small and weak, you might only generate 50 "units" of waste, when your kidneys can easily filter 100 "units" of waste per day. After you get big, you might start generating 150 units of waste from the weights, which will start to burden the kidneys. Riding on top of that might generate another 100 units of waste. Of course, the kidneys can still only handle 100 units a day, which makes for the beginning of systemic fatigue.
The important thing here is that muscle growth wil only take place after systemic recovery has taken place. Muscle growth is the last part of recovery. If you are never fully recovered, you will never achieve maximum strength/performance gains.