Headset cap bolt

sumosprintstar

I was tightening up the headset cap bolt on my bike today after a little bit of maintenance when the bolt just started spinning round. I had increased the level of my torque wrench without realising and the result is the part that the bolt tightens into has snapped off inside. What is the likely damage and what will need replaced? Does this bolt actually do anything other than hold the cap on? Everything seems tight enough in terms of bars and turning?

I would appreciate any advice as I am a bit worried that I have done some major and expensive damage. I have had a look on the internet but I am bit confused. Some human experienced advice would be great.

Thanks

arthur_scrimshaw

Which bolt are you talking about? The bolt holding the cap which screws into the expander plug/star fangled nut inside the steerer or one of the bolts which clamps the stem to the steerer? Only the stem bolts have a torque setting, the cap bolt is just to preload the headset and has no torque setting as it requires just a tweak to remove headset play?

doug5_10

Just bash a new star nut in (if its an alu steerer)

sumosprintstar

Arthur Scrimshaw wrote:

Which bolt are you talking about? The bolt holding the cap which screws into the expander plug/star fangled nut inside the steerer or one of the bolts which clamps the stem to the steerer? Only the stem bolts have a torque setting, the cap bolt is just to preload the headset and has no torque setting as it requires just a tweak to remove headset play?

Yes, it's the bolt holding the cap.

arthur_scrimshaw

sumosprintstar wrote:

Arthur Scrimshaw wrote:

Which bolt are you talking about? The bolt holding the cap which screws into the expander plug/star fangled nut inside the steerer or one of the bolts which clamps the stem to the steerer? Only the stem bolts have a torque setting, the cap bolt is just to preload the headset and has no torque setting as it requires just a tweak to remove headset play?

Yes, it's the bolt holding the cap.

Ok, as I said before, there is no torque setting for this, you tighten up the bolt into the SFN (star fangled nut) just enough to take out the play in headset bearings, very little force needed. You then tighten up the stem bolts to grip the steerer (normally to 5nm) You could then remove the top cap and bolt completely (but it would look a bit untidy)
If you've overtightened the bolt to the point that it's stripped the thread in the SFN you will need to have a new SFN fitted, but the good news is that you can just push the old stripped SFN further down the steerer tube and fit a new one. Unless you're mechanically apt this might be best left to you local bike shop.

Monty Dog

You need to understand what type of retainer you have in your fork - a star-fangled nut or a compression bung. If the fork has an alloy steerer, it will be the former and if carbon steerer, the latter. It's unlikely you've done anything serious - I suspect you have a star nut and the centre threaded piece is simply spinning around. The only hassle might be getting the headset cap off.

sumosprintstar

Thanks for the replies, really appreciate your help.