If you’re 18stone and a gear masher, then running lower than the RECOMMENDED 1.6:1 ratio (not 2:1) might result in the internals stripping. It has happened to at least one guy I know of who posts on MTBR forums. He admitted that he’s the wrong side of 18 stone though, and had put a 26T chainring on with a 22T cog on the back, and mashes the pedals!
So unless those criteria apply to you I wouldn’t worry…
I’ve got 34/22 setup on mine, it’s spot on for my 29er. I usually recommend 32/20 for most people running a 26″ wheeled bike as a starting point, maybe go for a 34T ring if you find it too easy, a 21T cog if you find it too hard.
If you want the excel spreadsheet, then email me (mbonnes AT gmail DOT com)… It is I that created it, more than happy for you to have a copy. Plenty of others on here will hopefully attest to its usefullness, it works out all sorts of stuff from the gain ratio to gear inches to speed per given rpm etc… Just drop me an email and I’ll send it to you…