I drilled out a stuck bolt

[pclay]

I took my rear mudguard off my alloy Cannondale Synapse the other day, and in the process, found that one of the bolts had seized.

It was the bolt that goes into the small length of tube near the bottom of the seat tube, (linking the two chain stays). What is this called? Mudguard stay?

I could not get the bolt out. Even after hacksawing a slot into it, a screwdriver would not budge it, and the head just crumbled away.

I ended up just drilling straight through to the other side. Will the fact that I have drilled through impact on the strength of the frame? Is my bike going to collapse and case me to crash?


Photos take with bike upside down, looking down onto bike.

Photo 1
This bolt ain't budging

Photo 2
I drilled it straight through

Photo 3
The hole nearest the camera was not there previously until l drilled it

Photo 4
The final solution. Bolt through the 'mudguard stay' with nut on other side.

 

[helston90]

I'm no expert but if I that that to my frame I wouldn't worry about its structural integrity no, that should be fine.

A zip tie would probably work very well in that place also and far easier to move after being caked in mud/ salt etc.

 

[mjr]

A zip tie may let the mudguard move too much and rub the frame, @helston90, wouldn't it?

I wouldn't expect that to have hurt the frame in that location (many bikes have no bridge there) but I'd be watching very closely for cracks developing and I'd take care to use a stainless nut/bolt. I think I would have cut the old guard off, left the rusted bolt in place and got a guard that uses a plastic clip at that end.

I think I'd call it the "chainstay bridge" but I've no idea if that's its proper name.

 

[Yellow Saddle]

As MJR said, that bridge is superflous and not structural. However, when you drill into any structure, whether the part is superflous or not, you always deburr the hole, inside and out, to prevent stress cracks. A stress crack could start in a non-structural part and propagate in to a structural part. Basically, tidy up that hole.

 

[Johnno260]

Would it be wise to coat the exposed metal with some primer?

 

[subaqua]

Would it be wise to coat the exposed metal with some primer?

Yes. And then some top coat as primer is porous

 

[pclay]

Well I did 9 miles this morning, and I am still alive. I don't really 'care' for this bike anymore as it is 3 years old and has done 10,000 miles, hence I was not too concerned about drilling the chain stay bridge. Its no longer my pride and joy. It is used daily. My old hybrid bike had the chain stay bridge drilled through as part of the design by the manufacturer.

I take note about de-burring the hole. I use air fix enamel paints for filling in chips etc, so will use that to paint the hole.

 

[Globalti]

Don't bother with paint; just fill the hole with thick oil or Pledge or Mr Sheen, the carnauba wax will protect the metal. Spray the bolt as well or use a stainless bolt.

 

[Yellow Saddle]

Well I did 9 miles this morning, and I am still alive. I don't really 'care' for this bike anymore as it is 3 years old and has done 10,000 miles, hence I was not too concerned about drilling the chain stay bridge. Its no longer my pride and joy. It is used daily. My old hybrid bike had the chain stay bridge drilled through as part of the design by the manufacturer.

I take note about de-burring the hole. I use air fix enamel paints for filling in chips etc, so will use that to paint the hole.

I doubt anyone is surprised that you are still alive after a whole nine miles or 10 000 more for that matter. I see no fear for your life with dire warnings here. All the advice mentioned is just good standard practice from people who are proud of what they do and don't hack away at jobs even when working on lesser objects. A burr always comes back to bite you - literally. Some time or other you will wipe your hand over it and end up with a whole drop of blood.

 

[Ajax Bay]

I don't really 'care' for this bike anymore as it is 3 years old and has done 10,000 miles, hence I was not too concerned about drilling the chain stay bridge. Its no longer my pride and joy.

I wonder if I'm alone in reading this and having a slight 'sinking' feeling. Take pride (and joy) in all your bikes. Care for them, though maybe not equally. This one is 'only' three years old.
Personally, I'd use a locknut ("a nut that resists loosening under vibrations and torque. Elastic stop nuts and prevailing torque nuts are of the particular type where some portion of the nut deforms elastically to provide a locking action") on the down tube side of the chainstay bridge.
Finally why not ask yourself why the bolt seized and take steps to reduce the chances of it happening to another bolt (perhaps on another bike) again.

 

[pclay]

I wonder if I'm alone in reading this and having a slight 'sinking' feeling. Take pride (and joy) in all your bikes. Care for them, though maybe not equally. This one is 'only' three years old.

When I say 'I don't care for this bike' what I mean is that is does not get cleaned after every ride like my summer bike. Otherwise I would be cleaning it 2 times a day, as I commute 10 miles each way mon-fri. I still do all the necessary maintenance on it.

 

[Tom B]

If your really bothered clean up the hole and stick a stainless steel nut and bolt through it. I replaced the nuts and bolts on my guards with quality ss soon after fitting.

 

[screenman]

Don't bother with paint; just fill the hole with thick oil or Pledge or Mr Sheen, the carnauba wax will protect the metal. Spray the bolt as well or use a stainless bolt.

Copperslip is your friend on sealing bits like that rather than pledge or wax that will be washed off very quickly. Use it everyday and sometimes see how it has stood up after years of use, it is clever stuff.

 

[DaveReading]

Next time around:

 

[Yellow Saddle]

Next time around:

I don't think so.