Should I avoid sitting on top tube on my carbon bike? In another bicycle discussion forum I encountered a thread about possibility to damage carbon frame by sitting on top tube while stopped.

I see some sense in it, as generally tube walls are a lot thinner in the middle to save weight and are not designed for this kind of load. The problem is, I have not seen any warnings from manufacturers about this habit, nor there are stickers on the frame suggesting to not do it.

So the question is - Is this a real problem, should I change my habits?



UPDATED: There is one local person who does carbon repairs, he claims that he has repaired multiple frames which had been damaged this way.
I have never had or heard of a problem.
Over at www.velominati.com, one of the rules is

Rule #80 // Always be Casually Deliberate.
Waiting for others pre-ride or at the start line pre-race, you must be tranquilo, resting on your top tube thusly. This may be extended to any time one is aboard the bike, but not riding it, such as at stop lights.

While some of what they say is tongue in cheek, this one is not. Most people I know do it, and have done for years.