system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is different with sport bikes that make them sound so high pitch compared to cruisers that sound so deep?
gpt
The RPM (rotations per min) at which the different motors operate, and their respective power bands, because of their different uses.

Cruises tend to have larger overall engines, working at a relatively low RPM to keep the bike, well, cruising.  They have a wide power band (to oversimplify, the same amount of power at most RPMS)  That is to say, best in a straight line, with few dramatic changes in speed or direction necessary.  They They're build for style and comfort.

Sport bikes, in contrast, operate at a very high RPM range, with a narrow power band (meaning it makes most of it's power in the high RPM range, so it needs to stay revved up).  They're build for speed and agility.

TL;DR the two engines are doing two very different things, so they sound very different.