The threaded fittings on my Brompton rear triangles that hold the roller wheels are called Rivnuts – they’re a bit like rivets, but they leave a threaded hole behind. I use them because they work very well, and if the thread gets damaged then they can just be drilled out and replaced.
Occasionally, they become loose – generally it’s the ones on the integral rack, because the end of the rack gets slammed down a lot when you fold the bike. If that happens, it’s an easy fix – I use a pneumatic tool to fit them, but you can re-fit them with just a nut, bolt and washer:
- You need a M6 bolt, 20mm long or so, a M6 nut, and a washer. You also need a spanner for the nut (usually 10mm) and an allen key for the bolt (usually 5mm).
- Assemble the bolt, nut and washer, and screw into the rivet as shown in the picture above. it doesn’t have to be tight, just screwed a good way in.
- Use the allen key to hold the bolt, and then screw the nut in against the washer and rivnut. The rivnut works by pulling the thread so the body of the rivnut flares out and grips.
- Tighten the nut as much as you can, then unscrew the nut and remove the bolt and nut. It should be tight now.
- If the rivnut has actually come out completely, and it won’t go back in, get in touch and I’ll send you some spares.