I'm not sure what you guys are considering big, but right now I've got 21.5" thighs. I've also got 39" hips and a 26" waist. That's the biggest hip measurement I've ever had

I did get into cycling to lose weight, but I've always had big thighs and after many years have come to accept them. I'm hoping to lose the fat (I can pinch 1.5 inches on my thighs so I've got it to lose) and I don't mind if I gain muscle to replace it. I'm hoping to get the hips back down to 37" (where they used to be) by losing fat from the butt (again, I've got a few pinchable inches to lose). I'm already muscularly well developed there and doubt I'll get much bigger through cycling, based on where I'm feeling the burn after rides.

That said, if you're my size I'd recommend investing in a pair of Seven for all Mankind jeans. I've never looked better in denim, and b/c of the 2% stretch they will fit the tiny-waist-big-thighs people, and they make the butt look good even when there's a little too much there. They are pricy but if you take care of them they will last. And the same pair that fit me with 37" hips still fits me well at 39", so if you fluctuate a bit up or down they'll still look hot.