Hi there ChowChow!

I can assure you, there's absolutely nothing wrong with your bicycle!

If your brake shoe was dragging on your rim, you were effectively working against yourself. This requires extra energy. Also, in cold weather, your body expends energy trying to keep itself warm. For older people, the metabolism tends to be slower. It takes more energy to heat the ole engine, in order to maintain thermo-stability. The lay-off could have caused your metabolism to slow down a little. If you're used to riding in warmer weather, psychologically speaking, you had quite a different expectation. Remember, we are homeotherms, not poikilotherms, we have to expend energy to maintain our core temperatures. This fact is magnified by age...

PS.

Quickly sell your aluminum framed bicycle! It's no good!

Buy instead, a more honorable chromoly steel-framed Jamis Coda Sport.

The Gods of Steel will bless you for it!