Bike sizing - Trek Superfly - what frame size AND GEOMETRY to choose?

[SickBiker]

 

[Lenshtina]

I'm 180cm tall, because of the very low price I consider to buy

29" Trek superfly 9.8 sl from 2015 but frame is L one year of use

or 26" Scott spark rc 10 size M from 2012 mint condition

I'm ex mountain bike champion in my country 13-12-11 years ago... But almost 7 years I'm off the race scene,  ride my bike for comuting and some maratons... My goal is to back in to the races

BTW I have similar riding style, body constitution and age like you... what do you recomand...

Q: is there a huge (big) diference in the wheel size 26" vs 29"  (I have never race on 29") or it's just markenting

Edited April 10, 2018 by Lenshtina