I personally don't like Time Remap since it's a) very unintuitive in its visual interface and b) forces you to maintain the original length of the clip when performing said speed changes. It's rare when I do speed ramps that I want to speed it up exactly as much as I want to slow it down right after. Usually, I just razor the clip and then use the Modify - Speed (APPLE-J) command to speed-change the part that's been razored out.