My Dahon Helios was squeaking over small bumps on the road. If you are like me, you`ll understand the squeaks drive me crazy. The squeaks sounded like they were coming from the bottom bracket by the pedals. I thought the bearings in the bottom bracket were toast but I was the wrong. Here is how to fix some sources of squeaks from your Dahon:
1. Clean and lubricate seat post.
2. Clean and lubricate seat adjustment bracket.
3. Clean and lubricate hinge joints where the two halves of the frame butt together.