Quick-release seat slipping down My bike's quick release seat has been slipping down recently.
I noticed when my (pro) biker friend remarked how low down the seat on my bike was, and helpfully readjusted it for me. Biking became easier. Yesterday, while biking, I noticed that biking was difficult again, so dismounted and checked the seat -- it was way down again.
So I fixed it.....but what can I do to make sure it doesn't happen again?
You have to make sure that you're actually tightening the quick release down - it should leave an imprint on your hand when you close it down. 

If you put a product like frame saver in the frame, you'll need to tighten it down extra since that makes seat posts super slippery. 

See this thread as well.