Help! I am trying to change my large chainring, and all the bolts have come out easily except one. And now it looks like the picture:

The slot into which the teeth of the wrench insert is so stripped, I can not hold it hard enough to budge the Allen bolt from the opposite side.

I have applied plenty of penetrating oil, poured boiling water over it (to heat it up), and placed a rubber band over the side I want to grip better. All to no avail. I now have blisters on both hands.

Any suggestions?

Drill it out

Sorry, no clue, but to prevent it happening again these are the shizz:

https://www.amazon.co.uk/Truvativ-Chainring-Single-Steel-Spacer/dp/B001GSQO3W

Drill it from the side you’re looking at with a new high quality bit. Take it slow and not a lot of pressure. Might need a vice to hold it do toy can use allen key in tg e opposite side. Also might need a coupe of passes with .5mm bigger bits.

But someone might be along with a less brutal solution. I can’t see how you could easily notch anything in the photod side without damaging the rings.

Best just to buy a New bike.

Picture suggests you haven’t removed the crank. Remove crank and try to clamp the chainring bolt spanner in place. Apply pressure slowly, don’t try to force or jolt it.

Picture suggests you haven’t removed the crank. Remove crank and try to clamp the chainring bolt spanner in place. Apply pressure slowly, don’t try to force or jolt it.

You’re right. Because the others came out so easily, I didn’t bother removing the crank. The idea of removing it and clamping might work.

Drill out,but give it a go with the Allen key, sometimes heat and vibration can help loosen things up.

Heating and cooling along with penetrating fluids like PlusGas would normally be my approach to avoid drilling… but without much to grip on to on the backside you’re going to struggle.

I’d be tempted to sacrifice the chainring and cut it off so you can get some molegrips/vice on it to hold it while you undo the bolt.

Start by giving it a good clean
All of the grease etc isn’t going to make your life any easier

I’d get someone to hold the allen key on the outer side and tap the sleeve around on the other side using a hammer and punch /screwdriver or small chisel etc in the best of the damaged slots . Once loose shouldn’t be difficult to undo/remove.

Thanks to all of you for the advice. I have finally managed by clamping the wrench to the bolt. There was just enough room to catch the edge of the small chainring and wrench, and it worked. No drilling, and no damage to the moving parts.

I’m thrilled. Cheers. 8)