I'm bad at searching, but I spent a fair bit of time looking for this. My People 150 squeaks when going over bumps at speed, but only when it's warmed up. If I jump up and down on it at a stoplight, it squeaks the same squeak. When I stop, take my helmet off, and listen for where the squeak is, I've only got about 30 seconds to make it squeak before its cooled down too much. (Found that out the hard way.) The squeak is difficult to generate by depressing the front brake and bouncing the handlebars up and down. It's easy to depress the forks and make no sound at all if I'm just a little gentle. The squeak is pronounced if I jump up and down on the seat, and in perfect synchronicity with my bouncing. When going over small bumps at speed, it sounds like baby birds in a nest cheeping. When bouncing on the seat it sounds more like a single adult bird chirping. (Like a Cardinal, if you know what those sound like. One loud, high chirp.)
The squeak SEEMS to be coming from right under or in front of my feet when riding, but I'm pretty sure I'm hearing echo off the road. And it's hard to locate with a helmet on. When hearing it without helmet, it seems to come from right under or behind the foot position, but I think I'm still getting some echo. I think it's the rear suspension pivot point. The problem is I'm having trouble locating a diagram of that in the manual and a description of how to lube it. I did find mention of a "Engine Hanger Bushing", but no diagram or procedure for maintaining it. Am I going to have to remove the engine, or is there a grease port on this thing? From judging the angle at which the suspension moves, it looks like the thing is going to be under the seat and plastics, above and toward the front of the engine. Does anyone know a manual chapter or page number that points this out, or a procedure for maintaining?
Thanks for any help!