Rivnuts

[docw009]

I bought a box of them several years ago, intending to mount a Hailong pack to an alloy downtube, but eventually used clamp-on brackets and hose clamps.

My current two projects are also alloy, but the step-thru frame tubes (Diamonbacks) are 48-50mm in diameter. and I've heard some talk about these thicker tubes being thin wall and not suitable for riv-nuts. The tubes are slso curved, so I suppose they aren't really tubes but some type of formed structure. SHould I say with tried and true, but ugly clamps?

 

[99t4]

Are there any threaded bosses on the frame already? (ex: water bottle mount, etc.) Those are likely rivnuts.

I have installed rivnuts to large diameter curvy step-thru aluminum frame to mount 13s5p battery with no problems.

 

[farina]

My experience with rivnuts has been mixed. Not infrequently, some time after installation, the nuts just sort of lose their
grip, and attempting to remove the screws just results in the nut spinning. This can sometimes put you in a very bad
situation, as you may need to remove whatever the screws are holding to access the rivnuts, but you can't.

 

[99t4]

Yes can happen. That's why it's very important to drill the hole slightly undersize, use good quality rivnuts, and install carefully.

 

[amberwolf]

Using rivnuts with "deep" grooves, (so the "ribs" stick far out, and preferably are not closely-spaced, so there is more material left grabbed between them, especially for thinner metal they're installed in), and sizing the hole to fit (or just smaller than) the core of the rivnut, not the outer edges of the ribs, can also help.

 

[Santacruz]

I have used them for years, at work and at home on many projects. I have never had a problem with them. One trick I use, is to coat the outside of the rivnut with stud lock (Loctite green). Then there is little risk of them trying to turn when you want to unscrew a fitting. It is also important not to over tighten the fittings. Find the correct torque for bolt used. I have used them on very thin to 3mm metal.

 

[RTIII]

Yes can happen. That's why it's very important to [...] use good quality rivnuts, and install carefully.

Can you suggest any brands? Metric perhaps?

 

[99t4]

I get mine at a local well-stocked (old school) HW store. They have quite a good selection. Aluminum, steel, various sizes. I choose the beefiest-looking ones with the deepest grip teeth for the size I need (usually 5 or 6mm). Sorry, don't know the brand. Yes metric, usually 5 or 6mm.

 

[m34tbag]

Flexing (and vibration) is the enemy of rivnuts. If whatever you've attached can move or cause the nuts to flex in their mounting, they'll slowly loosen off.
If they are spinning in their hole, sometimes you can jam a flat head screwdriver under the lip, twist it for tension then loosen the bolt.

Also consider the application and materials. using an aluminium rivnut in a steel frame (and vice versa) can be affected by galvanic corrosion. the steel rivnuts are generally better as they stay where you set them, but they do need more force to compress them, so you have to be more sure you set them tight to start with.

 

[Wattman]

Sharing some personal experiences as I have had good luck with riv nuts on modern aluminum bicycle frames with heavy battery ebike applications.

For a big, heavy battery like a shark type 20 amp-hr size, I suggest four points of attachment to a frame. I personally use a Grin Triple Bob which really stabilizes the battery laterally...but also fashion a little spacer in the rear of the battery for a four attachment behind the Triple Bob and placing a Riv nut above the two water bottle attachments.
Less stress on each riv nut is a good thing.
Other couple of tips is, I use a 2 part epoxy like JB Weld between the riv nut body and ID of the downtube hole drilled in the frame. This not only increases strength but mitigates corrosion.
A last tip is, use only enough grip strength to make the Riv nut nice and firm as it expands with squeezing the plier ends of the insertion tool. If you use excessive grip strength which I really don't have in advancing age, you can spoil the thread in the Riv nut. Basically the insertion tool uses the thread via axial force against the flange of the Riv nut constrained by the tool head to mushroom the Riv nut body to expand it radially inside the hole. The threads can be spoiled with excessive grip strength.
I always use stainless Riv Nuts...M5 in an aluminum or steel bike frame.
My lessons learned by trial and error.