Originally Posted by Allen_Wrench
You could just pedal. Or coast. That's probably as quiet as you can get.
The latter is what worked for me when I left my condo complex this morning. I pedaled until I was at the entrance to our complex by the main road, then I fired 'er up and off I went. I can make all the noise I want out there. Besides, half the fun of these little bikes is makin' noise.
In all seriousness, if quiet is what you're after, convert it to electric. It doesn't get much quieter than that unless you power it yourself with the pedals.