Sizing help

monkeysm8

Having decided an Audax bike is for me, I am trying to determine what size bike I need. I am 5' 7" have a 31" inside leg measurment using the 20cm feet apart method that I found surfing about. I normally ride a 15.5" or 16" MTB frame if that's of any help lol.
Cheers

Mister W

Try this website - http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR_INTRO

This will give you an idea of the frame dimensions you should be looking at. Don't forget that the top tube length is the most important as it's far less adjustable than the seat height.