I had started thinking about a rail bike about five years ago while still living in Connecticut. There is an extensive no longer used rail system running along the Connecticut River for many miles. I started hiking along the old tracks and found that a lot of the side hills had slid down and blocked the tracks. The other issue was that much of the tracks had to cross over small creeks and streams entering the river that were supported on old trestles that were in bad shape. I mostly forgot about the idea until moving to Florida and finding an extensive rail system that is no longer in use and I decided to rekindle the rail bike project. The rail system here is not very old and is in relatively good condition except for the vegetation that has grown up from lack of use and maintenance.
I’ve been looking at images and videos of rail bikes trying to come up with a design that would fit my needs. One of the concerns that I uncovered through listening to what people had to say on forums was that the traditional rail bike that rides on top of the rails with a standard bicycle with an outrigger and a front rail guide sits pretty high up in the air. Having reached an age where being brittle is a factor in the things that I do I decided to design a more low to the ground recumbent style bike. Living in an area where sourcing materials can be somewhat challenging I had to make do with what was on hand locally. I decided to make the majority of the frame out of half inch EMT tubing which I can get at the hardware store. The local bike shop donated some parts which I cut up and made into the front and rear wheel supports. The seat which is adjustable was found on a abandoned lot.
There is an issue with the pedal / bottom bracket and seat position. Most recumbent bikes have the bottom bracket higher than the seat. Although I have seen a few designs where the seat and bb are on the same plane, who knows if it works well. I have found that the seat should have a 115 degree offset compared to the seat bottom. I will mock up something to try with some boards and wire ties.