With all the rain, mud and drive train destroying sand, I'm contemplating getting a no nonsense single speed and keeping the Yeti for favourable conditions. -

The negatives of a single speed include climbing and limited top speed, while pondering these the idea came to me to make a 3 speed bike by having the single rear cog, fitting a chain tensioner, front derailleur and 3 chain rings?

Does anybody know if this is possible?