Tips for removing worn chainring bolts?

ColinJ

Puzzle game procrastinator!
I have some seriously worn chainring bolts - no chance of undoing them with an allen key (of the right size).

I don't want to buy a special tool to do the job. I have watched a couple of YouTube videos which didn't help.

I have thought about hammering a screwdriver into the rounded off hex heads. I have also considered trying to tap them round using a hammer and punch. The third possibility that I have considered is using a hacksaw to cut the ends off from the other side.

If someone has a better suggestion, please tell me before I embark on some serious bodgery!! :laugh:
 

swee'pea99

Legendary Member
 

cheys03

Über Member
How about drilling them out from the front (Allen head) side? Bit at a time with increasing sized HSS drill bits. Once down to the last mm and enough material is removed, be extra careful as the bolts are steel but chainrings/crank spiders are usually aluminium which is softer. Perhaps consider collapsing the last mm ‘ring’ of steel chainring bolt with a screwdriver/chisel and hammer rather than risk drilling it. It might have fallen apart by then from all the drilling anyway.
 

cheys03

Über Member
Thinking further on it the chainrings bolts might just spin if attempting to drill. An alternative may be to hammer in a slightly larger torx bit into the wrecked Allen socket to grab the bolt, supporting from the back with a block of wood so the chainring is not bent when hammering. Then undo using the above linked proper chainring bolt tool for the back.
 

cheys03

Über Member
I know you don't want to buy a special tool, but these will absolutely do the trick. Also useful for things beyond the bike.
be careful with this sort of remover in this situation, not to say it won’t work but as the cone-shaped thread on the tool is tightened it can put pressure on the (external to it) chainring bolt threads, locking them together more as they’re pinched between the tool and the chainring.
But, there should be enough meat in the chainring bolt to stop this happening.
 

Gunk

Guru
Location
Oxford
The other solution is to get a local engineering company to remove them. I’ve done this with stuff on my motorcycle and they’ve got all the right kit and expertise.

Or chuck it in the bin and just buy a new complete crankset, which by the time you budget for extraction tools and new chain rings, will probably work out at about the same cost.
 
Thinking further on it the chainrings bolts might just spin if attempting to drill. An alternative may be to hammer in a slightly larger torx bit into the wrecked Allen socket to grab the bolt, supporting from the back with a block of wood so the chainring is not bent when hammering. Then undo using the above linked proper chainring bolt tool for the back.
Hammering a Torx in would be my method too.
 
OP
OP
ColinJ

ColinJ

Puzzle game procrastinator!
Nice bodge! But...
These are cheap enough. A sound investment. [Long link]
... I already have one of those AND that side isn't the problem.

The problem is that where there should be a hexagonal hole for an allen key, the cross-section of the hole is nearer to being a circle!

I know you don't want to buy a special tool, but these will absolutely do the trick. Also useful for things beyond the bike.
I had heard of those but was expecting them to be a lot more expensive. That isn't too bad - thanks!

An alternative may be to hammer in a slightly larger torx bit into the wrecked Allen socket to grab the bolt
Hammering a Torx in would be my method too.
I haven't got one of those, but it does sound like a possible method.

The other solution is to get a local engineering company to remove them. I’ve done this with stuff on my motorcycle and they’ve got all the right kit and expertise.

Or chuck it in the bin and just buy a new complete crankset, which by the time you budget for extraction tools and new chain rings, will probably work out at about the same cost.
This sounds like a very effective solution. Unfortunately, the reason that I didn't want to buy a special tool is that I am skint! That also rules out paying professionals and buying new parts...

I have just watched a few more videos. Some effective solutions including knocking the bolt head round with a punch or chisel. Quite a few people suggested hammering a Torx bit in.

One suggestion I like the sound of is filing a taper onto a larger allen key and hammering that in. I'm sure that I will have a spare allen key somewhere that I could use and I have a file so that would be a free solution.

I hadn't appreciated that there are metric and imperial allen keys. (For some reason I thought that they would all be metric sizes.) One of the videos suggested that accidentally using the wrong type could lead to rounding off the hole and I'm wondering if that is what I did in the first place?
 
I hadn't appreciated that there are metric and imperial allen keys. (For some reason I thought that they would all be metric sizes.) One of the videos suggested that accidentally using the wrong type could lead to rounding off the hole and I'm wondering if that is what I did in the first place?
More likely to be a worn Metric allen key that rounded em off unless you have some random Imperial ones in your toolbox, AFAIK all chainring bolts are Metric.

As a former Pro car mechanic we'd sometime hammer in an Imperial Allen key that was slightly bigger if a bolt was rounded out but then someone invented torx which do the job far better.
 
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