Hi all
Was trying to change bars and stem on wife’s mtb tonight and possibly or should I say definitely over tightened headset screw which sheared of the bit screw goes into at top of fork. Basically am I buggered or can this be fixed by lbs.
Sorry if answer is obvious, but bike mechanic im not……..

Thanks

Old star nut just needs hitting out and new one pressed in. Won’t be a problem for most lbs and will be £20 tops I reckon

Thanks much appreciated

I’ve done this before (aluminium bolt and thinking “just one last tighten”). If you have a drill with a thin enough bit, what I did was drill into the sheared bolt, then reverse drill to unscrew the bolt.

If the head has come off, does the top cap remove? If so you can likely just use pliers to unscrew the remains of the bolt and fit a new one.

If it’s sheared at the star nut then hit down star nut and put in a new one would be easiest. Don’t even need to remove the old nut, just knock it down enough to fit a new one.

Drilling the bolt will be a faff and you may need HSS or Cobalt drill bits, more so if it’s a stainless steel bolt. Masonry or wood bits will just die drilling bolts, though you might be okay with a soft Aluminium bolt. Reverse drill may or may not work and if not you’d then need a bolt extractor.

As per Dead Kennedy ^^

I dread to think how much torque you put in to shear an M6 bolt, especially if it’s a steel one – perhaps it was somehow faulty ?

You do know it’s only job is to put the correct load onto the headset bearing races don’t you ? It has nothing to do with holding the stem/bars in place – that’s what the two pinch bolts are for, and even they only need about 6 or 7Nm torque.

You might want to check you’ve not crushed the headset bearings, although it’s most likely that they’ll still spin OK, but will probably not last as long now.

Good luck 🙂

Thanks to all for the replys. Disc jockey you’ve got it in one I was tightening has if this was needed to keep it altogether. All that’s left in the fork is the black spidery thing, so as as said will get knocked out and new fitted. By the way was only using multi tool but with to much enthusiasm.
Wife’s just caught me typing so have had to tell her…….. happy days
Again thanks