epnnf

Anybody use them? Of course, theyre lighter & dont rust. Bicycle applications dont require much from a fastener? Ive always used them to plug 'brazeon' holes. Now, Im wondering if they could be used to secure a cage or mini pump. Or even on brake or shift lever clamps?

canopus 

You will use all the way up the the first time they break and you have a crash avoidance with your bottle (equipment) and you have to ride back to get it and then carry it home.

HillRider

For bottle cages not used with big bottles like 2L soda bottles they may be OK. Maybe. For any critical part like brake or shift levers, absolutely not. Many bicycle applications require a lot from a fastener and the trivial weight savings is foolish. If you have rust problems buy stainless steel fasteners.

I have used them to secure fender struts since they will break away if if something like mud or a stick gets jammed between the tire and the fender. Here their lack of strength is a benefit.

Iride01 

Seems like just trying it out and getting some first hand experience would give you a better answer than a bunch of guesses from us.

However I think you'll find that after a few hundred miles your bottle cage or pump mounts will be pretty loose if they didn't shear off from times you bumped up against it.

What's the issue you want to solve? Bolts and nuts are pretty cheap and easy to find if you know where to look for them.

ClydeClydeson

Bottle cage or mini-pump - maybe... I'd guess they have a 50% chance of holding on for a few rides. The problem is that a rigid bike frame transmits a lot of road shock to everything attached to the frame, and 1 L of water is 1kg of mass that needs to be accelerated and decelerated along with the frame, and nylon bolts will not withstand this for long. I suspect a minipump fastened with nylon will hang on better under regular riding forces, but nylon bolts might fail after you pull the pump from it's mount multiple times.

Anything else, though? No. Brake levers clamp? Nope. That's a very stupid and dangerous idea. Fasteners are chosen based on the strength of the material that is originally planned for the application. Replacing steel bolts with lighter (and weaker by X-sectional area) is risking broken fasteners, and these replacement materials are usually titanium and aluminum - far far stronger than nylon - and they still pay a reliability penalty.

Andrew R Stewart 

This. It can be surprising at how strong the vibration forces are. Our bodies are very good at damping our control center from these forces (our brain is at the end of a flexible and muscle damped spring called a spine) and thus we often don't give much credit to what the rigid bike parts are seeing.

When I had a shop in Cleveland I was lucky to befriend a really smart guy. As in dual PhDs in mechanical engineering and medicine. He was also a daily bike commuter and wasn't happy with the lighting options at the time (late 1980s) so did his research and came up with a LED tail light in a plastic housing. During his prototyping he had a few issues with the small wires he would solder (threaded contacts failed the exposure factors). These wires would flex and vibrate with the shocks and in time break. (He mentioned his next move was to design and get made a tiny circuit board housing the battery contacts too). The process stopped after a couple of years due to two reasons.. One was that he learned that getting a patent was too costly and offered no real protection from copies, and second was the Vista Light came out. I brought one back from the Fall bike show the first year Vista was producing them. The look on his face said it all. he saw the product he had been working on for those years as a refined and slick package. Andy

UniChris

Blocking holes or mini pump perhaps, and maybe the breakaway idea.

But I wouldn't do even a bottle cage - what are you going to do when it breaks?

Last month I was very glad though that my unused seat tube bottle cage mounts had real socket head cap screws in them - discovered one of the screws for a (since replaced) rack that I'd carelessly installed had vibrated out and fallen off, but was able to take one of the unused bottle cage mount screws to fix it, and temporarily cover that hole with some electrical tape.

70sSanO

I would think the cost to make plastic bolts/fasteners “might” be cheaper than steel.

If that is true, you have to think about it. When an industry obsessed with cost and weight doesn’t use them in those applications, it isn’t because they haven’t considered it.

John

RGMN

I design wiring harness for heavy-duty off-road vehicles. ANY soldered wire will break in a vibration environment. I've seen literally hundreds of tests and field reports, and soldered wires are one of the most common failures. There's a reason that high reliability applications use crimp on contacts. Military and space are an exception, but they use assemblers that have several hundred hours of soldering training and have daily soldering checks.

As far as nylon fasteners, one machine I worked on handled chemicals that would corrode metals very rapidly. Everything was fastened with nylon fasteners. The trick was that if we would use an M5 steel or stainless screw we had an M8 or M10 nylon fastener there instead. Made for some ridiculously large fasteners, but everything held together, even after bouncing all over a field for a few months.

dsbrantjr

I have worked in both military and space and the use of crimped terminations was common and is getting more so. Even with trained assemblers using thermal strippers and anti-wicking tweezers and all of the other controls the soldered connections are still troublesome. Plus, few want to do the very exacting work and many lack the hand-eye coordination.

veganbikes

If you are desperate for weight savings aluminum or titanium is a fine way to go but plastic not so much. For plugging a frame sure but beyond that I wouldn't use them for anything else. The very minimal weight savings to hold a fairly heavy water bottle for something that won't last is beyond not worth it.

Ogsarg

If you look you'll see there are nylon compounds that are primarily nylon and there are nylon compounds with fillers added . For fasteners, you may have glass-filled nylon making it stiffer and easier to machine but it's still not very strong. Nylon stretches quite a bit on it's own making it difficult to put any real torque on a fastener so unsuitable for just about anything on a bike in my opinion.

There are some special plastics that might work although will be harder to find and maybe expensive . Acetal is one that has good strength and not expensive although you may not easily find what you need. PEEK is another but that it very pricey.

For the gram or two per fastener you may save, I really don't see it being worth the effort and risk of having something come apart mid-ride.

FastJake

Bicycle fasteners have been refined and standardized for over 100 years. They are dimensioned around the strength required of the given material. If they could've used a smaller nut or bolt, they would have. Nylon is much less strong than steel. Therefore, you would have to use a much larger bolt to get the same strength. So you probably wouldn't save any weight...

A notable exception is water bottle bolts. In this case, M5 is used because it's a common size on bicycles, not because you need two steel M5 bolts to hold a water bottle. Replacing them with titanium or even aluminum can be ok. I would be very surprised if nylon worked for more than a couple rides.

In case it hasn't been made perfectly clear, DO NOT replace any bolts with nylon if they have to do with safety or structural integrity (brakes, stem bolts, etc.)

IPassGas

I have those black plastic breakaway tabs on my front fenders. They tend to allow the metal stays to rattle loudly. Replacing the tab with a 5mm nylon screw seems like a good fix. Do you have experience or have talk to others that know the nylon screw will break away in the event of fender jamming?

cxwrench

Other than plugging braze-on holes or maybe fenders forget it. You'd be absolutely nuts to use them for brake levers/shifters. That's just plain stupid.

WizardOfBoz

dsbrantjr, we just had dinner with my neighbor. He owns a welding machine supply and repair company. He was telling me about tig welding inconel jet engine test probes - he had to hold his breath for about 60 seconds to ensure that there were no discontinuities in the weld. I think that you're right: very few have the patience and skill to do that.

Oh, and to the OP: NO FLIPPING WAY! Brake bolts? I submit that bike manufacturers have worked to whittle down costs ruthlessly. And even on Walmart BSOs, they use metal (mostly steel) bolts. There's a reason why they dont use plastic. Stainless has about 8 or more times the shear and tensile strength of a strong plastic (e.g. PEEK). If you're concerned about corrosion, use stainless or Ti (with anti-sieze). Plastics just can't be relied upon in critical fastener service.

HillRider

Fortunately, I've never jammed anything between my tire and fender that gave the bolts a test. I used them based on a recommendation in an article I saw in a bike touring magazine and it seemed like a good idea.

blacknbluebikes 

This is trying to solve a non-problem. But the engineering color is interesting.

ClydeClydeson

This statement seems to indicate that you are not too familiar with bicycle repair and function. With the exception of waterbottle bolts, just about every fastener on a bike is appropriately sized, and any changes that weaken the fastener (smaller size, less-strong material) will result in a broken fastener sooner than later.