Or, if you don't want to use a tool, in the Used Bike Buyers Guide text portion, I have a table worked out with Trig 101 that requires the seattube & setback measurements to decipher the angle. It is more time consuming than a tool but yields an accurate angle determination. I've posted this to the list before, but as I recall it doesn't "cut and paste" very well. Perhaps someone who has the guide from me can cut and paste from their version to see if it will translate any better. Lou Deeter, Orlando FL