Schweinhund

They use non-expansive inserts, but not rivnuts. rivnuts on a bicycle, are a dumb idea. solder/braze/bond.

A rivnut uses expansion to grip the material it's inserted into.
The metal in a bike, in order to be light, is thin. any place you would drill a hole is a compromise in round tubing add to that the expansion of the rivnut to the hole in the tubing and now it's distorted and you have a recipe for a crack.
​​​​​​​Have it done right, use a kit that is non intrusive, or use a camelback.

Paul_P

If the frame tube can be considered a beam, I've read that drilling holes in the middle of the sides of a beam are ok, but not the bottom or top which are in tension/compression.
So not only is the rivet pushing the hole outwards but the forces on the tube are also trying to stretch it wider or squeeze it narrower.

Kontact 

No, rivnuts are standard in factory frames. It's a dumb idea to suggest soldering/brazing/bonding small hardware into aluminum or carbon tubing.

DVC45

A ruined frame can be expensive....

Schweinhund

My good sir, I've worked with metal the vast majority of my life. Rivnuts are great in the right application. bikes ain't it. You braze an insert to manage the compromise you just created. You bond one for the same reason. If factories re rivnutting, it is a cost saving measure. doesn't make it the right way or intelligent. And, if you bought a custom frame or high end frame, there will be no rivnuts.

Broctoon

I would not drill holes in the frame of any bike I really like. Maybe you'll get away with installing rivnuts and find they work well, maybe not. For me, it's not worth the risk when you have other options. SKS anywhere adaptors are good. I use them on one bike. (Two Fish makes a similar product.) Or, as suggested above, you can always use hose clamps. Put some tape or rubber under them to protect your paint. They're not aesthetically pleasing, but they work very well, they're cheap, and they're easy to install. I use them on one of my bikes. None of these options is permanent, so if you change your mind, they're easy to remove.

If you'd like pictures of these solutions, I'll take some tonight and post them.

Broctoon

Here’s my bike with a bottle cage held on by hose clamps. They’re not a very elegant solution, but they work great, and on some bikes they don’t even look too out of place.







I have this track bike that I never ride on a track, because we don’t have one in my state. But it’s fun on the road. It just needed a way to hold water. The SKS adaptors are surprisingly strong and stable.

Kontact 

My good sir, I've worked in the bicycle industry since the '80s. Rivnuts - despite whatever opinion you have - are entirely normal in non-ferrous frames. High end titanium, carbon, aluminum all have them. There are certainly exceptions, but those exception are much less common. Of the six classic Ti framesets I've owned, only the Litespeed Classic had welded cage fittings. The Merlin Extralight has rivnuts. It was quite definitely a high end frame. And so were all the other astronomically expensive bikes I was preparing for sale just a year ago.

There is no application for your advice because it has nothing to do with reality. Rivnuts are so common that you would have to be a blind cyclist to not notice them. They aren't the slickest thing in the world, but they have the advantage of being very reliable and easily replaceable, which isn't true of more permanent attachment methods.

And for a person looking to add them to a bike that needs them, rivnuts are really the only intelligent choice at the shop level.

Kontact 

I wouldn't put hose clamps on any bike I would be seen on, or was concerned about the paint.

tFUnK

I bought one of these for the rare occasion that I'd want a third bottle. Turns out the strap isn't long enough to go around my fat down tube, but they also include zip ties to do the job. To be fair I haven't tried using it yet: https://a.aliexpress.com/_mLhCp4q

Schweinhund

Let's find out. I contacted Merlin.

Schweinhund

looked at ten of mine
1995 marin eldridge grade, - brazed
1986 Specialzed rockhopper -brazed
unknown year fixed - silver soldered
1991 Schwinn High Plains - brazed
1990 Specialized rockhopper - brazed
1986 Centurion Elite RS - silver soldered
1978 Sekai 2400 - brazed
1983 Specialized StumpJumper - Brazed
2007 Bianchi Brava - silver soldered
1998 Gary Fisher Mt Tam - nutsert
Surprised about the Fisher.

Schweinhund

2000 Trek 6000 - nutsert
1991 KHS Montana Comp - nutsert
2003 Cannondale F400 Femme nutsert
1989 Bianchi Super Grizzly - Brazed

Kontact Kinda guessing I may get bad news on the Merlin.

spclark 

Couple weeks ago I hung a CF water bottle carrier on my MB's downtube using some rubber insulating tape (not the adhesive stuff) for cushioning and a couple of ZIPties. Seems to work just fine for the purpose: tape keeps things from sliding around, ties hold carrier in place nicely. Not the most elegant solution, also easily removed should the need arise.

Kontact 

See my note again about "non-ferrous frames". Though I'm not surprised that a welded steel frame uses rivnuts instead of having a single feature brazed.

My Merlin was made in the '90s by a company that doesn't exist anymore. The current Merlin is part of Ti Cycles.

Broctoon

You probably would be embarrassed to be seen on some of my bikes. I have a range, from pretty nice/clean/tidy ones to a few that include some... what shall I call it... backyard engineering, a.k.a. kludges. But I don't go full-on janky "who cares?" mode. There is no damage to the paint from hose clamps on my frame pictured above.

When considering how to solve any problem with a bike, I often ask myself, "What would Sheldon do?" That guy was so intelligent and so pragmatic. He would laugh at many trends in biking today. I'm sure he would laugh at the carbon fiber bottle cages I have on one bike. He would certainly give thumbs up to my cage secured by hose clamps, with rubber tape to protect the frame.

For what it's worth, I have no issues with rivnuts installed by someone who really knows what he's doing.* I stand by my statement that I would not drill holes in a nice bike frame. Letting a trained professional do it--that's another matter.


* Are amateurs who consider installing their own rivnuts aware that you don't just drill a hole, insert the piece, and expand it using one of several types of special tool? Any rivnut that's designed to withstand moderate torque through repeated use will have an anti-rotation tab under its flange. You have to use a needle file to cut out a notch where this tab will fit. In a round tube, that notch should be at the 12:00 or 6:00 position. Not a big deal, but something to be aware of.

Kontact 

Not only are amateurs not aware of that, but professionals aren't either - because it isn't true. I have never replaced a rivnut on a bike that had anything but a round hole in the frame.


(I'm always amazed how much is discussed on this forum that appears to come from a complete lack of experience.)

Broctoon

You got me. I’ve never installed a consumer grade rivnut, or whatever kind bike mechanics use. I’ve done a few in aircraft applications, and that grade of rivnut works as I described above. I still wouldn’t drill holes in my bike frame. Other guys, be they amateurs or pros, can do as they please.

This is the kind I have experience with:



From the manufacturer:
”These plated steel Rivet Nuts are similar to Insert Nuts (Part No. 655-Size) but they can also perform the dual function of permanently fastening several pieces of sheet metal together (like a pop rivet) while providing a permanently captivated nut for mounting a removable piece. We stock the keyed type which offers superior torque-out resistance (file a small notch on the edge of the mounting hole for key). Install 10-32 Rivet Nuts into a 1/4 inch hole. Use a Q size letter drill for 1/4-28 Rivet Nuts.”

Kontact 

Yup, not an aircraft forum. Bikes.