Yes, Basically we are an online antiques road show. To answer the question. No. One cannot predict the value of a vintage bicycle because they change all the time. At least not in the way the email was lamenting about... as in some kind of guide. An enthusiasts watches the market and invests lots of time into watching what things are being bought and sold for and can predict the value on any given day based on that knowledge. However, generally that value is only valid for a short period of time as market forces changes. So one could waste untold amounts of time and put together a price guide which would likely be invalidated by the time they were ready to publish it. The guide would then influence pricing and become another factor for the following year on the prices people tend to pay. It would just be another of the many market forces at play.