Beautiful shots! I suppose now is the time to go, before it turns scorching.
We got pretty lucky - the week before we arrived they had lots of rain and snow, with daytime temperatures not too much above freezing. Every day we were there we had blue skies with hardly a cloud in sight. The coolest day was 12 degrees Celcius, and the warmest was 22 - perfect cycling weather. I hear that the weather turned for the worse just after we left, which is probably the norm for this early in the season.
Late April through May is your probably your safest bet for nice spring weather. It can get pretty hot even in June, and July and August are just stupid-hot.
My first trip to Moab was in late October for the Fat Tire Festival (probably 1993 or 94). Even that late in the season, daytime highs were over 100 degrees F. Not much fun trying to ride a bicycle through the desert in those temperatures.