Cycling UK Forum

I've been assembling a pair of mudguards that will fit nicely on my bike with 20" wheels. As part of the work, I've used pop rivets. I notice that the steel core stays in the popped rivet, but that it can be fairly easily removed. Is it supposed to remain in place - or is it supposed to come out, leaving the rivet as shown? I'm inclined to remove the remains of the pins, as I'd rather take the inititiave than have them drop out at some unspecified time in the future, and risk them sticking in the tyre...

Normally, a pop rivet should retain the steel core. They can be removed, but the rivet would lose its strength.
Also, a pop rivet isn't the best thing for a mudguard as the steel will rust.

I've used stainless nuts and bolts on my Moulton.
Photos to follow when they've uploaded from my phone into the cloud!

I always leave what is left in the rivet and maybe file off any rough edges. I generally use steel rivets though and those look like aluminium. I would say if the pin comes out easily then remove it otherwise dont worry.

What you're describing is called the head of the mandrel.

Sometimes they come out by themselves and sometimes they don't. If they don't they can rattle, they can rust, and they could possibly drop onto the tyre as you describe.

TTBOMK the strength of the fastening isn't affected by whether you leave it there or not.

Jonathan

PS: Are you using a washer to spread the load on the inside of the mudguard?

There is open end and closed end blind (pop) rivets, I have mostly used the open end alloy ones, on occasions a bit of the steel shaft does seem to break off and get stuck in the hole. I would tap it out with a punch.

as far as I know the open end alloy ones don't leave any steel parts within the rivet?

Jdsk wrote: ↑14 Jan 2023, 9:34am TTBOMK the strength of the fastening isn't affected by whether you leave it there or not.

In this application that's probably correct, in others the body left on it's own will be subject to deformation if there's any twisting force. They are clearly designed to be left in, if they're lose the rivet probably wasn't correctly applied, or was the wrong size.
I'd agree with Mick F, that there's better fixings for this, they're called blind rivets and that's the only time I use them, where I can't access the other side.

Standard pop rivet.
I "popped" into the workshop and riveted one in a hole in a hinge.

Note the steel inner shaft.

Thanks folks. The section of 'guard using the pop rivets is tiny - barely three inces long and so very light. It's intended to sit directly under the front brake. There's not much room under there! The rivets have washers as shown.

In your situation i would support the rivet head and use a ball pein hammer to spread the rivit shank into a mushroom to provide extra support.

I'm going to give that a go. I quickly checked up on ball pein hammers and was surprised to see so many variants !

A ball-peen or ball pein hammer, also known as a machinist's hammer, is a type of peening hammer used in metalworking. It has two heads, one flat and the other, called the peen, rounded. It is distinguished from a cross-peen hammer, diagonal-peen hammer, point-peen hammer, or chisel-peen hammer by having a hemispherical peen.

Blimey !!

If your hammer dosent have a rounded head then just use the flat head. Gentle tapping, don't bash it like a nail.

If you don't have a pop rivit tool then removing the steel mandrel and careful use of a hammer can achieve good results too.

I have reused those aluminium rivets used to hold the plastic handle on items like washing powder boxes.

rjb wrote: ↑14 Jan 2023, 10:20am In your situation i would support the rivet head and use a ball pein hammer to spread the rivit shank into a mushroom to provide extra support. :wink:

I believe the so-called Yorkshire Ripper, Peter Sutcliffe, used a ball peen hammer. (Probably too much information.)

Pop the mandrel out and pein it over. Looks neater and in this sort of situation it will be more that strong enough.

Monel metal blind rivet are available.
They are used in marine applications such as aluminium masts.

Monel, any of a group of nickel-copper alloys, first developed in 1905, containing about 66 percent nickel and 31.5 percent copper, with small amounts of iron, manganese, carbon, and silicon. Stronger than pure nickel, Monel alloys are resistant to corrosion by many agents, including rapidly flowing seawater.

https://www.spaldingfasteners.co.uk/mon ... for-boats/