Hello. Just been told my head tube may have accelerated the failure of my headset (the cup sheared off).

One cause of this (aside from 6 years of hard riding) may be the lack of a chamfer on the inside of the head tube.

To ensure this doesn’t happen again how to I get this done? Dremel? File? Take it to LBS?

Please enlighten me!

pics of the head tube with clear need for a tidy up, might, stop me calling Bull.

A wha?

I’ve never done it, but I’ve never faced a head tube either. It makes sense – chamfer gives room for curve in the angle of the cup. A quick google suggests headset manufacturers speccing a 45 deg chamfer between 0.25 and 0.50 mm

From Chris King service manual…

One aspect of preparation that is often overlooked is the chamfer on the inside of the head tube bore (top and bottom) and the removal of any sharp edges or burrs. (See figure 1 – last page.) We recommend a chamfer width of .25mm (.010”). A clean chamfer allows the cup to be pressed without shaving metal and to sit flat against the tube face without cutting into the small radius in the corner of the cup skirt. A cut in this area of the cup may cause cracks to form over time.

Headtube chamfer? Owch. Can be nasty that. You can get a cream for it, which should bring the swelling down. Best to stay off the bike until it clears up.

I normally do it with a deburring tool.

Never heard of it but sounds sensible. Just taking the sharp corner off should be enough. A little rub with sandpaper/wet and dry/Emery/a file should do it.