Whenever we ride, we can always see some riders sitting on the frame while waiting for traffic lights or chatting. There are different opinions on this on the Internet. Some people think that it will be broken sooner or later, and some people think that the ass is so soft that nothing will happen. To this end, well-known bicycle writer Lennard Zinn called some manufacturers and industry people, let’s see how they answered it.

According to Chris Cocalis, founder and CEO of Pivot Cycles:

I don’t think there should be a problem sitting on it unless you have something sharp or sharp in your pocket. As long as the pressure is not highly concentrated at one point, even a lightweight carbon fiber road frame should not be afraid. If you’re still worried about using a repair stand, just wrap a cloth with some cushioning like a sponge.

According to Brady Kappius, founder of professional carbon fiber repair company Broken Carbon:

Please do not! Especially for users of high-end road bikes, we strongly advise against this. The pressure of the butt sitting directly on the top tube will exceed the design range of the frame, and there is a possibility of damage. Some depots put a “don’t sit” sticker on the frame, not to scare the user. The wall thickness of many ultra-light road frame pipes is only about 1 mm, and obvious deformation can be seen by pinching with fingers.

According to Craig Calfee, founder and CEO of Calfee Design:

In the past work, we have received some frames from different brands and manufacturers that were damaged by users and sent for repair. The frame top tube is seated cracked which is beyond the normal use of the bike and is usually not covered under warranty. Frame top tubes are not designed to withstand longitudinal forces, and loads inside the tube are ineffective. There is a lot of pressure on the top tube when sitting on it.

According to Lightning Bike Engineering Director Mark Schroeder:

I’ve never heard of anyone sitting on a tube and ruining our brand of frame. We don’t think you should clip the frame top tube to the repair rack, though.

Different manufacturers and people in the industry 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 carbon fiber road frames, especially ultralight frames. And mountain bikes, especially soft tail models, don’t have to worry about them because their top tube is strong enough.