Hip pain out of the saddle I am getting hip pain (both sides) when climbing hills out of the saddle. I am conscious to not choose too higher gear to get my cadence right but I end up back in the saddle spinning as they get so sore. Any thoughts? My quads are fine and when I use the spin bike to practice out of the saddle, this doesn't happen. 
Happy for any help as training for a short triathlon and need to get my riding right. 
Thanks in advance!
I think this hip pain is an indication of fatique, which will diminish through ptactice.

I experienced this once.  

I had been cycling for more than 20 years and was skillful with out-of-saddle ride.  I did this every now and then for say less than 1 km for fun.

Last September I challenged myself to a total of 10 km climbs (8 discontinous climbs stretched over 36 km) out of saddle. The gradients varied from 5 to 10.

The following morning my hip joints hurt.  Then I realized it was fatigue.

After a week I rode the same route again to test.  This time there was no more fatigue.  

I think practise and rest and practise, and the pain will go.  My experience.