I was riding my kh20 and I noticed a dinging noise coming from it (like metal on metal). I checked the seat bolts, but that wasn’t it, I also checked to see if it was the seat string with the plastic tip hitting the seat post. I’m not sure where it’s coming from, I’m guessing maybe a loose eye-let on the wheel, but other than that I don’t know what could be causing it.
An unitight spoke 
Happened with me a while ago, I probably forgot to tigh only one, and it started to make a weird nois…
Check your spokes
I haven’t had it that long, I guess a spoke may have gotten loose, I haven’t tightened any though.
If it isn’t the spokes…
It could be the pedal, it could be loose, or if you have loose pins, they can make a noise too.
Make sure everything is tightened.
Areas of Noise
Seat post not tightened to saddle
seatpost not tightened to rail
Rail adaptor not tightened to saddle
Bumper handle not tightened to saddle
Bearing caps not tightened
Pedal not tightened to Crank
Bad bearings in Pedal
Crank not tightened to Hub
Loose Spokes
I think it’s the pedals, I’ll try tightening them up.
I was just going to post a thread on this exact topic. The same thing has been happening to my KH 20. Now I don’t need to bother posting a new thread…in fact, this whole reply was pretty useless as well. Anywho, thanks for the tips everybody.
its loose spokes.
new pedals don’t [normally] make noise.