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Broken bolt
OK, so replacing the mudguards on my bike today. Well, trying to. The head of the bolt which connects the mudguard to a bracket on the chainstay bridge sheared off as I was undoing it. So the bolt hole now has the body of the bolt screwed into it, with no way of getting hold of it at either end to remove it...
I can't be the only person this has ever happened to... Does anyone have any suggestions for getting the damned thing out??
Thanks 
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18 comments
As others have said, I would try a bolt extractor first. Drill a small pilot hole first, then the correct sized hole. If you can get the bike held steady in a workstand it will be much easier. Use penetrating fluid before trying anything.
If that doesn't work, and the frame is aluminium and the bolt is steel, you can also dissolve it. You ned to be able to dip the whole thing into water though so it depends on the shape of your bike and the shape of your container. I have sucessfully used Potassium alum (as used for making pickles) in hot water. Won't work if the bolt is stainless.
Does it also work for cable ties ?
How do you stop the solution falling out ?
The answer is obvious - you need a new bike !
If going with Welshboy's advice below, use quality extractors, other wise you may end up with a brittle but very hard piece of steel embedded in the remaining stud, with no way of drilling it out.
Ensure that the stud has been well soaked in penetrating oil - it's no guarantee. but can help
Use a small diam pilot hole first, drill out as wide as you dare before using the extractor.
TIG is overkill, will likely damage your paintwork, and if you have a steelie you stand a chance of welding the stud to the hole, unless you're very, very good. Even then if the stud was so well fused that the bolt sheered off, there's every chance that your TIG build-up will too.
I'd seriously consider though your LBS's advice re-cable ties if possible
Oddly the above experience was gained from a similar issue with a clutch plate bolt shearing in the flywheel on my kit car a few weeks ago. I ended up redrilling and threading the hole as close to the original as poss. I didn't think of using cable ties.....
Thanks for this, people.
I think I'll ask very nicely, casque in hand, at my LBS and see if they are willing to do this (as a billed job, obviously).
The bolt in question is the one that came with the mudguards, and the bike, when I bought them twelve years ago, so it's seen a bit of wear and corrosion...
I got halfway through explaining it to my LBS and the guy cut me off and said, "Use cable ties"
"Yeah, but..."; I started again.
"No - seriously, just use cable ties".
Cable ties worked! Who knew?
The rear mudguard has a vertical slot cut into it, I presume so you can adjust how far up/down the front of the mudguard sits (or, conversely, how far up or down the rear of the mudguard sits?).
So, I've used bolts to hold everything else, but then I have cable ties going around the chainstay on each side and looped through the slot in the mudguard. Two cable ties, then (it's not like they're load bearing...).
I usually carry a few cable ties with me on my bike - you never know when they might be useful (e.g. impromptu snow tyres).
Sounds a little ugly. I'm still going with new bike as the answer.
In my defence, you have to look pretty closely to notice them.
But there was this very nice looking New Bike in a local shop...
Yeah, but you know they're there
I'm with Hirsute. New bike....
You may need the help of someone with a TIG welding kit. The process is to gradually add weld onto the stub of the bolt until you have enough material to grip with a pair of locking pliers (Mole grips). Of course if your frame is carbon that's a non starter.
I agree, you could always get someone with a TIG welder and gradually build up enough metal to grab with mole grips (mole grips were made in the city where I live, there used to be a sign on the factory just as you go in to the M4 tunnels saying "Newport, the home of the mole grip")whilst trying not to damage your frame or paintwork or you could pay £6.59 and try to do it yourself https://www.ebay.co.uk/itm/402978954190?_trkparms=ispr%3D1&hash=item5dd3...
I did see Ed or it could have been Ant doing this on a stud that had broken in an engine on Wheeler Dealers.
Probably try carefully drilling it out. Any chance of a pic?
Please. The way you've written it, the bolt is stuck in the bracket, not the frame. Can you buy or fabricate a new bracket?
... the bolt which connects the mudguard to a bracket on the chainstay bridge...
There's a metal plate behind the bottom bracket, welded to the chainstays, which is where my kickstand is attached. The plate also has an upright, part of the same piece of metal, and the troublesome bolt is stuck in that.
A drill and a stud extractor, you need to drill a small hole as close to the middle of the bolt as you can then use the stud extractor (loads of cheap ones on eBay) which is basically a tapered left hand thread, as you screw in in the taper grips the bolt and because you are winding it in "backwards " it undoes the old bolt. 5 minute job then spend 30 seconds greasing the new bolt before you fit it 😀