Is it possible to add easing to a looping, time remapped precomp in After Effects? I have a 1 second precomp that is a rotating wheel using LoopOut(). Using Time Remap this animates during my entire main composition which is about 20 seconds.

I'd like to include an ease in so that the wheel starts turning gradually before rotating at a constant velocity. Doing this to the first time remap keyframe is obviously wrong, as the ease then happens every second. Is there a way of doing this without making the precomp 20 seconds long? (I found a longer precomp was slowing down the rendering.)
Add an expression control slider to the layer (Effects>Expression Controls>Slider Control). This will be what we use to control the rotation of the wheel.

now add this expression to the time remap property:

effect("Slider Control")("Slider") % 1


You could also drag the expression pickwhip from the time remap property to the slider property, and then type % 1 after the result.

The % 1 is the modulus operator, it returns the remainder when the first term is divided by the second, in this case the part after the decimal point, so if the slider is at 12.34 it will return 0.34.

Now you can animate the slider using whatever easing you like.