Fixed thanks

joel222

So I bought a new stem and when fitting it I believe that I over tightened the single bolt that goes into the headset. It didn't seem to nip up so I kept turning and the bit inside what the bolt screws into has slid up the tube. Have I ruined it, is it safe to ride? The bolt is into the bit inside the headset but that bit (sorry I don't know the correct term) is not fixed in place, it doesn't slide if I pull it but by screwing the bolt its enough to pull it up.

whyamihere

It sounds like you have an expander plug inside the steerer tube, which is a bit loose. They normally tighten with a 6 or 8mm hex key. The bolt that you were tightening is only needed to preload the headset bearings, you don't need to really crank it.

The Rookie

Is it an expander plug or star fangled nut?

https://www.ebay.co.uk/itm/391717592106

https://www.ebay.co.uk/itm/140994620357

The bolt really only needs to be nipped up to preload the headset, more and you overload the bearings and shorten their life.

joel222

It is a star fangled nut, I've pulled it out, straightened the fins out and put it back in and its worked. I really need to get torque wrench. Thanks for the replies.

The Rookie

You shouldn't be using a torque wrench on a top cap, perhaps it would be better to read up on how to do it?

02gf74

I think you need to get a new star fangled nut - the "fins" are made from spring steel - it should be virtually impossible to pull it out and also impossible to straighten the fins.

as mentioned already, it only needed to preload the headset bearings - do it up until there is no slack in the headset - after that, it is the bolts on the stem that hold the stem to the fork steerer. some people to save weight remove the cap and bolts but it will act as a safety devince should the stem bolts give way (very unlikely).

The Rookie

Safety in that the bars just spin uselessly rather than coming off in your hands - its all relative!

Either way a nasty ending is pretty much inevitable!