There has been an on going saga/drama I have had to deal with regarding the seat frame on my Vison R40. I have had the bike since 2001. In that time frame 5 of 8 welds in the seat frame have broken and been repaired. Advanced Transportation, the company who used to build Vision recumbents went out of business and before they did they redesigned the Vision frame and seat frame. As a result I can not find an exact replacement anywhere that will work with my bike. I did find at Hostel Shoppe a seat frame that with the use of an adapter and some other adjustments to my bike would work to fit with my Vision frame. The problem is the geometery is differant than my original and it hurt my hips and lower back to ride it so I had to return that seat frame and adapters as a result. I have been wanting to have a custom seat frame built out of 4130 cro-moly for some time. I found a shop that builds funny cars, drag racers and does custom work on classic muscle cars that can build one, but for almost $700. A new bike would cost me $1800. I gave up for a while until recently. I found another shop that builds custom motorcycles who will do it for about $300. I have no problem paying that much. The shop owner is using my existing seat frame to get the geometry correct. It will be ready by the first week of March. The problem with the aluminum seat frame is multi-fold. First it is not heat treated. Second it is fastened in to places to the cro-moly bike frame. There is constant vibration transmitted up through the seat frame causing the fatigue thus resulting in the failed welds. I have said this once and I will keep saying it: Which would you rather sit your ass on? A material that has been wround for 2,000+ years and is tried, trued and tested? Or a material that has barely been in use for about 200 years and by comparison is still in it's infancy? Can cro-moly or steel fail? Yes. But I wager it will last a whole lot longer than aluminum. If the guy who is building this seat frame does as good of a job that his reputation has shown I will give him a huge kudos and spread the word if anyone in my area needs custom fabrication done for a motorcycle or bicycle to contact him.