How much is my Zinn frame worth?
1984 Zinn, 63 ctc. Shimano EF dropouts, Columbus SP tubing, Cinelli lugs. could use a repaint, but not rusty or anything. It was the 81st frame he ever built, no serial number.
What's a fair price?
DRF aka Thrifty Bill
Repaints really knock down the value of a bike. So if it really needs a repaint, the value is going to be down quite a bit. Big size is also a significant negative. The sweet spot in sizing is in the 54cm to 60cm range. Bikes/frames under that size sell for a premium. Frames over that size sell at a discount. I have had a couple of bikes with 63cm frames. They took a long time to sell.
It certainly is a high end, niche frame that is going to have some serious value. Its all about condition, and finding a buyer looking for a frame that size.