The thing about lycra knicks is that they slowly fade away. Or wear away. With every ride and wash, they get a little bit thinner.
Until you can see through large patches of them.
Here's a question for you - you're riding along and you catch up with another cyclist, and as you close in, you discover that you can see their entire bum.
1. Tell them about it
2. Look away
3. Follow them for the next 20 km