don`t know, it seams to me that it`s 100% ok , I can go bigger than with larger ratios, I just use my body alot:D, and i guess that when i go for 18 - 15 (try-all fw or eno) after i get used to it it will be alot easyer:D, and yeah i now it`s obvious, but i can go with the smallest runup distance you know:)), it`s fun when you can pedal up where other riders sidehop or pedal kick