I'm slightly taller than you at 1.81m, and I demoed both the large and medium strive last year. Both fit me fine, and if I was forced to choose I'd probably go with the medium. Definitely felt a bit more nimble and playful.
Thanks for the info Im definitely leaning towards a medium as the jump from a 10 year old 26er bike to modern bike with modern geo and reach numbers and to top it off a 29er
Turns out after doing a proper measure I'm a fraction less than 5'10'' which as disappointing as it is I've lost height helps a little with the sizing

I'm taking a mate of mines 2018 spectral-on out for a spin the weekend after checking geometry geeks site, it turns out the reach is 5mm longer and the stack is 9mm less in the spectral medium so should give me a good idea on how the medium strive will feel
Thanks for the input and thanks everyone for the help
The sizing should be the easiest part when buying a bike but loosing too much sleep over it

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