Have a Spesh 09 Sworks FSR, size small – that I built recently. Crankset is XTR M980 3×10 – 175mm.

I have noticed that I have been having a fair few strikes while out riding – pedals striking ground while leaning/riding shallow ruts etc etc.

Now, according to the spesh site and the bike specs, the size small came with 172.5mm crank arms.

Having looked around – I cannot find a XTR 2011 crankset with 172.5mm crank arms – but can find 170mm.

Questions: Is it worth swapping out the crankset for 5mm differance in crank arm length, will this resolve the issue? Or, is it because the bike has a lower clearance (bb height) etc?

the crank length spec by spesh would probably have been simply for biomechanical reasons – diddy people have diddy legs and shorter cranks are a good idea. It would have helped towards avoiding pedal strike too, but as you say, by 5mm.

However, if you look at the spesh website the BB height’s on the geometry pages dont seem to change across the frame size range, so it’s possible that you dont actually have a low BB, just a poor riding style 😉

I’d give it a few more rides before going to the expense of changing the cranks for the sake of 5mm. Lower BB heights do come with the risk of more frequent pedal strikes but you soon learn to deal with it and adjust your riding style to suit.
How have you got your rear shock set up? If it’s on the soft side, or it’s a shock that blows through it’s mid stroke to easily then that might also contribute to the pedal strike problem.