Combining Shimano RS500 crankset with Stages Shimano 105 5800 I've been thinking about getting a power meter for a while now. I finally decided I would get one, but now I realise that Stages only starts at the Shimano 105 level.

I currently have a Shimano RS500 Crankset ( 50 x 34 ) and I'm very pleased with it, so I don't feel a need to replace the whole crankset with a 105 5800.

I also have no plans to upgrade anytime soon to Dura Ace or something like that (the rest of my bike has the 105 5800 set), so I don't think I should buy a higher lever crank arm from Stages.

Now, I know something about bikes, but not a lot. It seems that what I have (RS500) looks compatible with the 105 crank arm (just judging by the looks), but I would like to be certain before I spend this amount of money.

My set: http://www.bikester.be/398351.html
Stages I would like to get: http://www.powermetershop.de/en/stages-power-meter-shimano-105-5800

Kind regards and thanks in advance,
Many individuals are running non matching hollowtech II stages crank arms with no ill effects.

Stages themselves cites this as OK. 

Note the Dura-Ace crank below.

Crank Compatibility: All Shimano Hollowtech II road cranks

Go ahead and purchase with confidence and enjoy cycling with power.

I run an Ultegra 6800 Stages on a 6700 Crankset personally.