Post by thistle on May 18, 2011 21:34:49 GMT
As this is such a common issue and everyone is really interested in it ;D I thought I would share how I fixed the bottle cage threads on my frame myself.
The threads for the bottle cage bolts are not tapped into the frame itself (probably because it is too thin and it's too soft) and they are not brazed on threads either. They are formed by putting an aluminium rivet into a pre drilled hole in the frame and crimping it to hold it in place. All that stops it spinning is the friction between the rivet and the frame (i.e. not much). If the bolt seizes, gets cross threaded or is done up too tight then it overcomes the friction and you can't get the thing out.
The proper tool for installing the rivets costs between £20 and £120. As my bike costs me too much money to run anyway I wasn't going to fork out that much for the tool
Anyway, you will need:
Here's my frame with the broken rivnut removed (snap the bottle cage off, grind away for 15 minutes with a Dremel, retrieve bolt from inside the frame tube somehow). All that scraping of the paint is from trying to prise out the seized bolt.
Disassemble the rivet tool by pushing out the bolt in the handle. Watch out because it is spring loaded and try to make a note of how all the bits come out. Installing a rivnut is like blind riveting which is where the idea came from to use the rivet tool for this job.
Put the bolt back in the rivet tool and push the threaded rod through the hole in the top. It just fits on mine.
Put a nut on the threaded bar to stop it dropping through
Stick the washer(s) on the end of the threaded bar. You need just enough sticking out to screw the rivnut onto.
By the way, this is what a rivnut looks like
Screw the rivnut onto the end of the bar
When you squeeze the handles, the tool pulls the bottom of the rivet up. The top part is not threaded so it compresses under the force like so
With the (uncompressed) rivet on the end of the tool shove it in the hole and squeeze.
You need to squeeze quite hard, but not too hard otherwise you will deform the metal of the frame. The rivnut should squash quite easily so when it doesn't seem to go any more, let go and check that the new rivnut isn't loose (doesn't rock and doesn't spin).
Unscrew the threaded rod from the rivet tool. This will unscrew it from the rivnut.
Ta dah
It isn't perfect. One side is slightly deformed but not excessively. This is probably because I squeezed a bit too hard or didn't have the tool straight when I did.
If you use thin washers, the force will deform them and the rivnut will also deform. The thicker the washers the better.
Now the hardest bit - reassembling the rivet tool
Drop all the bits that came out back into the tool, making sure they do back in the same way. This is how they fit in mine:
The spring goes on top of all the bits
That little hole on the front of the tube below the big hole on the side is very important. If you don't have one, you might want to drill one in
Use a big flat headed screwdriver to push the spring down inside the tube
While you are holding the spring down, shove a pin of some sort through the little hole to hold the spring in place so that when you take the screwdriver out the spring doesn't pop back up. You can use anything that is reasonably stiff. Anything you have lying around - the stem of a blind rivet, the probe of a multimeter, a bike spoke etc.
Shove the large pin back into the tool through the tube. You might have to squeeze the handle a bit to get the holes to line up. When it is in, whip it out (the pin).
Happy riveting ;D
The threads for the bottle cage bolts are not tapped into the frame itself (probably because it is too thin and it's too soft) and they are not brazed on threads either. They are formed by putting an aluminium rivet into a pre drilled hole in the frame and crimping it to hold it in place. All that stops it spinning is the friction between the rivet and the frame (i.e. not much). If the bolt seizes, gets cross threaded or is done up too tight then it overcomes the friction and you can't get the thing out.
The proper tool for installing the rivets costs between £20 and £120. As my bike costs me too much money to run anyway I wasn't going to fork out that much for the tool
Anyway, you will need:
- Some rivnuts (off eBa or stolen from someone who works in an aeroplane factory)
- A blind rivet tool (£6-7 from Wilko which I already had)
- Some threaded bar (off eBay again, but you can use a long bolt or steal some off someone mechanically minded)
- Some washers - 5mm hole in the middle, 10-12mm diameter and quite thick (2-3mm). Or if you can't find one use a stack of tapering washers from the pound shop like I did.
- A 5mm nut
Here's my frame with the broken rivnut removed (snap the bottle cage off, grind away for 15 minutes with a Dremel, retrieve bolt from inside the frame tube somehow). All that scraping of the paint is from trying to prise out the seized bolt.
Disassemble the rivet tool by pushing out the bolt in the handle. Watch out because it is spring loaded and try to make a note of how all the bits come out. Installing a rivnut is like blind riveting which is where the idea came from to use the rivet tool for this job.
Put the bolt back in the rivet tool and push the threaded rod through the hole in the top. It just fits on mine.
Put a nut on the threaded bar to stop it dropping through
Stick the washer(s) on the end of the threaded bar. You need just enough sticking out to screw the rivnut onto.
By the way, this is what a rivnut looks like
Screw the rivnut onto the end of the bar
When you squeeze the handles, the tool pulls the bottom of the rivet up. The top part is not threaded so it compresses under the force like so
With the (uncompressed) rivet on the end of the tool shove it in the hole and squeeze.
You need to squeeze quite hard, but not too hard otherwise you will deform the metal of the frame. The rivnut should squash quite easily so when it doesn't seem to go any more, let go and check that the new rivnut isn't loose (doesn't rock and doesn't spin).
Unscrew the threaded rod from the rivet tool. This will unscrew it from the rivnut.
Ta dah
It isn't perfect. One side is slightly deformed but not excessively. This is probably because I squeezed a bit too hard or didn't have the tool straight when I did.
If you use thin washers, the force will deform them and the rivnut will also deform. The thicker the washers the better.
Now the hardest bit - reassembling the rivet tool
Drop all the bits that came out back into the tool, making sure they do back in the same way. This is how they fit in mine:
The spring goes on top of all the bits
That little hole on the front of the tube below the big hole on the side is very important. If you don't have one, you might want to drill one in
Use a big flat headed screwdriver to push the spring down inside the tube
While you are holding the spring down, shove a pin of some sort through the little hole to hold the spring in place so that when you take the screwdriver out the spring doesn't pop back up. You can use anything that is reasonably stiff. Anything you have lying around - the stem of a blind rivet, the probe of a multimeter, a bike spoke etc.
Shove the large pin back into the tool through the tube. You might have to squeeze the handle a bit to get the holes to line up. When it is in, whip it out (the pin).
Happy riveting ;D
