No idea what your problem is but the first two photos below are a great stretch. Do it on a table or whatever is the right height for you until you can lean forward and touch your nose on the table. Great stretch which has had more impact on my cycling flexability than any other.

http://www.fortcollins-massage.com/gluteus-maximus-pain.html

If you want a lot of bar drop, yopu really nead to be able to do this easily