Short term immediately (the next day or two) after a hard ride is normal. Overwork "injury" to muscles causes water retention in the area the same way as any other physical injury causes swelling.

Also, there are fewer calories in lean tissue than fat, so it's possible to burn fat and make lean muscle tissue weighing more without a surplus calorie intake.

Weight is a poor measure of what's going on in your body. Things like waist size, the old "pinch an inch" test help round out the picture that weight alone only shows a corner of. My personal preference for an overall indicator is specific gravity. I dive, and use no weights when at good fitness, but if/when I gain weight, I need added ballast to sink that fat. In my case (we all vary) I need roughly 1# of ballast for every 3-4 pounds of weight gain (using the same wetsuit and dive equipment).

The other indicator I use is the height of the narrowest part of my waist. When fit, I'm significantly narrower a few inches below my lowest partial rib. I tend to gain weight at the waist and as I do so, my narrowest point moves up into the taper of my rib cage. So the "does the belt ride up or down test tells me immediately that I need to cut out ice cream for a week or two.