Originally Posted by
TurbineBlade
I like the idea of keeping some muscle on my upper body and usually do sit-ups and pushups 2 times per week during down time.
Push-Ups & Sit-Ups are bodyweight exercises, not weights.
How do you do
weights while cycling? 
For the body to adapt, you should be looking at doing your weights at least 2-3x per week. Same volume (Reps/sets), same intensity & once your body/CNS has adapted, increase the volume/intensity/weight... The body won't adapt/strengthen at 2 times per week.
<<< I'm wrong there, sorry.