Will it crack? When waiting for the red light, can you sit on the tube?

    Whenever we ride, we can always see some riders sitting on the frame tube when waiting for traffic lights or chatting nagging. There are many opinions on the Internet, some people think that sooner or later it will be bad, and some people think that the butt is so soft that nothing will happen. To this end, Lennard Zinn, a well-known bicycle writer and author of "Road Bike Maintenance Guide" and "Mountain Bike Maintenance Guide", called some manufacturers and industry insiders to see how they answered.

Chris Cocalis, founder and CEO of Pivot Cycles, said:

    I think unless you have something sharp or sharp in your pocket, you should have no problem sitting on it. As long as the pressure is not highly concentrated in one point, even a lightweight carbon road frame is not afraid. If you still have concerns when using the repair rack, just find a cloth to wrap some cushions such as sponges.
Brady Kappius, founder of specialist carbon fiber repair company Broken Carbon, said:
    Don't! Especially for users of high-end road bikes, we strongly advise against this. The pressure on the butt sitting directly on the top tube will exceed the frame design to withstand and there is a possibility of damage. Some automakers put "don't sit" stickers on the frame, which is not meant to scare users. Many ultra-light road frame pipes have a wall thickness of only about 1 mm, and obvious deformation can be seen by vigorously pinching with your fingers.

Craig Calfee, founder and CEO of Calfee Design, said:
    In the past work, we have received some frames of different brands and manufacturers that have been damaged by users and sent for repair. The upper frame tube is cracked, which is beyond the normal use of the bike and is usually not covered by the warranty. The upper frame tube is not designed to withstand longitudinal forces, and the load inside the pipe is very ineffective. There is a lot of pressure on the upper tube when sitting on it.

According to Ryan Cannizzaro, founder of Alchemy Bikes:
    I think that although the upper tube is not designed to be used to sit, its strength should not be able to sit badly.
Mark Schroeder, director of engineering at Lightning Bikes, said:
    I've never heard of someone sitting on a tube and breaking our brand's frame. However, we do not think that the frame tube should be clamped to the service frame under any circumstances.
    Different manufacturers and industry insiders have different opinions, but because there are really not too many cases of sitting on the top tube, and the materials and processes of each manufacturer are different, it is impossible to generalize. However, it is best not to sit on the top tube of the carbon fiber road frame, especially the ultra-light frame. And mountain bikes, especially soft-tail models, don't have to worry because their top tube strength is high enough.