There is plenty of sprung adjustment in the handle of the pump to take up the "slack" between the stated range. The pump handle can be compressed within the stated range to ensure a snug fit. HOWEVER, Topeak's sizing table is based on two assumptions: Firstly that you have a top tube that's horizontal, and secondly that you will fit the pump alongside the seat tube, between the bb shell and the top tube. If you have a compact frame (where the top tube slopes downward to meet the seat tube), measure the ACTUAL seat tube length, if thats where you want the pump to fit. OR, if you want it to fit it under the top tube, measure the centres between the head tube and seat tube to get the right fit.