airport gears...explain rpm characteristics

specifically on average - what is the drop in RPMs between shifts with airport gears? 900? the average drop in RPMs for "normal" gears? 1500?

Here's a good site. Tom Conway's Carquip.

http://www.carquip.com/parts/gchart/charts/index.asp

There is also an Excel spreadsheet that can be downloaded to play with ratios, tire sizes and R&P's.

Tom

thanks tom,very helpful web site