Niner Air 9 sizing question

Trying to figure out if I am a small or medium. I am 171cm tall, 80cm leg. I have a medium giant anthem 27.5. The chart says small is recommended up to 173 cm but I am told a medium would be ok too.
It’s for shorter rides mainly, xc.
Any advice?

I’m 5ft 8,I’m a 17.5 in air 9,I had a 70mm stem but probably could have done with a 60mm,hope this helps.

Thanks. How does 17.5 read across to small, medium, large etc? Large? I am looking at this table http://www.jensonusa.com/Mountain-Bikes/Niner-Air-9-SLX-11-SPD-Jenson-Bike-1?cs=Red

I just bought a Niner, not an Air 9, but followed the Niner size recommendations,sizing was spot on.

RIP 9 , I am 5 10 tall and would normally ride most manufacturers large size frame.

With Niner it was a medium , just right.

Hope this helps.

Looking at the geometry I think medium might be me, with a 70 or 80 mm stem. Anyone else got experience sizing a niner air 9?

I had an Air 9 a couple of years back and followed their sizing guide. I went for a L as they suggested but I found it to be very long in the TT and not the most comfortable bike to ride as a result.

On a side note, I found the quality of the finish on the frame to be dire. The paint chipped incredibly easily and it started to look pretty well used after very little use. For the money I expected better quality.
Personally that put me right off Niner frames.

My Niners are medium and I am 5’10” 32″ leg.

Lot’s of seatpost, 100mm stem slammed bars, seriously nippy.

That’s including the Air 9 RDO and the One 9 RDO both the same M for my 5’10”

(Edit: Stem choice is just what I like, you could put an impossibly short stem on if that’s your bag)