Ableton Forum

How do you slowly speed up a song without changing the pitch. For instance, say you were to start a song at 80 bpm and it goes gradually speeds up to 110bpm over a couple minutes. How do you do this?

Assuming you're talking about the Arrangement view, you can click on the Master track, expand it out using the little triangle so you can see the two drop down menus. One will say "None".
Click on that one and select "Mixer", then select "Song Tempo" from the second drop down menu.

Then you can double click in the mixer track where you want the tempo to start increasing, then double click where you want the tempo to stop increasing. This should create two nodes for you. Drag the second one up to alter the tempo as you need...

and hold ctrl/cmd for finer increments

Oh, and if you want to do it in the Session view, you'll need to make loads of scenes with no stop buttons in them (so they don't stop what's playing) which are named the different tempo increments - 100bpm, 105bpm, 110bpm, 115bpm etc etc ad nauseum...

I just assign knobs on my controller keyboard to be rough and fine tempo adjustments. Works ok...