Maohaus

Still a newbie to BF, so if this has already been done, or suggested, my apologies.

I would love to have a master list of known components, frames and bikes that are known to fail, and which cause catastrophic accidents. It seems to me that this should be a "sticky thread" so nobody falls victim to a C & V part that may cause a serious injury.

jeirvine 

Interesting topic. I think there could be a short list of mostly forks and a few stems that could be listed:

Forks:
Ishiwata fork crowns on some early 80's Treks
Viscount Aerospace aluminum forks
Bianchi Randonneurs had a fork recall

Stems:
AVA - not sure exact model

JohnDThompson 

This site has been around for a while:

https://pardo.net/bike/pic/

steelbikeguy

The quill stems with cone expanders can be problematic.
Here's a shot of an AVA stem of this type:



The real problem, as I understand it, are the slots near the cone expander...



the slots appear to be cut with a saw, leaving sharp corners at the top of the slot. The sharp corners concentrate the stress, making it easier for cracks to start there when the cone (at the bottom of the quill) is tightened. Cracks in the stem are obviously (I hope) not a good thing, leading to the stem being loose in the fork or breaking entirely.

An interesting detail of these stems is that the extension is often hollow, as shown below:


This is an interesting detail, and kind of neat, but this sort of non-circular hole was made by casting the aluminum in a mold, which means that the stem was not forged like many of our favorite stems. Cast aluminum has less stength and a shorter fatigue life than forged aluminum, partly from the increased porosity and poorer grain structure.
A side effect is that the stem is quite flexible! That's why I got rid of this particular stem. ... plus.. it was a 22.0 quill, and the bike needed 22.2mm.

Steve in Peoria

Maohaus

My software security would not allow access to pardo.net.

obrentharris 

If you drop the "s" from "https" in the URL you will open it just fine.
Brent

Maohaus

Yup, dropping the "s" worked - wow, that is quite a collection. I am amazed at what people have time to do. Great resource no doubt. Still think it would be helpful to hear from the brain trust here in BF's!

icemilkcoffee 

grant40

1. Spinergy Rev X wheels.

2. A lot of the old French stems such as AVA and Atax.

3. The Viscount Aluminum forks.

3alarmer 

...most older aluminum alloy stems and bars (the ones without reinforcing sleeves, made from less sophisticated alloys) will eventually sag, and then fail. There are some aluminum alloy cranks that have something of a reputation for breaking at the pedal eye, or cracking at the spider, like Campy NR.

We still use them, because the failure rates are smaller, as a percentage of those made and used. But yes, the AVA stems were especially problematic at a certain spot in time, due to both design and the thinning of the castings down near the expansion wedge.

I take a close look at anything aluminum I'm reusing on a bike build. Here is a photo of bar and stem taken off a PX-10 that was rode hard and put away wet.

John E

First-generation Sugino Mighty Compe cranks. (Been there ... done that. I broke one across the pedal eye during an out-of-saddle climb. Minor injuries only, but definitely not fun!)

Significantly, the 1973 and later versions had another mm of material on both sides of the pedal eye, an increase of about almost 20 percent.

I have broken frames, rear axles, front hub flanges, cottered steel cranks (non-drive side, across the cotter eye), pedal cages, and spokes, but without any danger of injury.

Dfrost 

Some cranks are prone to very small cracks at the juncture between drive side arm and spider, like this one (Specialized “Flag”) below that can lead to eventual failure. The always popular Campagnolo Record is known for this issue.



Good news is that it can be corrected if caught early enough by carefully filing that location below the depth of the crack. Here’s the same crank after that treatment:

SurferRosa

If everyone got his choice of sticky, current threads would start on page 10.

There's really only a couple pseudo dangerous items worth mentioning.

JohnDThompson 

I went to remove the "s" in the link I provided, clicked on "Edit" and saw that the link I provided did not have the "s," so something in the vbulletin software is adding the "s" in the link it displays to users.

Weird.

Maohaus

Well, I guess the BF can decide which items are worthy to be stuck. Personally, I think rider safety would be a worthwhile, if not essential, stick. If just one person avoids a catastrophic event on a CV ride it would be worth it. There are a lot of parts and frames floating around out there and it would be a shame if someone was injured or killed simply because they were unaware of a part that was potentially a hazard - especially considering these items are nearly 30-60+ years old!

scarlson 

The first- and second-gen Phil Wood BBs are known for breaking. We have one in my family that my dad bought very early (first gen) and he broke it so then he got it warranteed and updated to second-gen and passed it on to me, and I broke the second-gen and got it warranteed for a third-gen and now I'm probably safe because I don't think the third-gen ones have a bad rep.

Many BB axles have known stress-risers in silly places. The old Viscount ones with the snap-ring grooves, and I think there's some FSA ones like that too. The Phils I think start to crack at the tool marks on the roughly-machined flats of the square taper. The ones that don't have these marks and have a more gradual lead-in to the taper are much less susceptible to cracking.

3alarmer 

...as I stated earlier, all aluminum alloy bicycle components that old ought to be inspected carefully before re-use. I have had stuff fail while riding, like a bar I broke once, near the stem. Yet I had ridden thousands of miles on similar bars prior to that date. Now, I toss them, rather than re-use them. There are a lot of creative ways to hurt yourself on a bicycle, and almost everything will break if you either use it long enough, or provide enough stress on it, even frames.

I know you mean well, but even if a list of stuff goes up here, and is maintained in great detail, people are gonna use stuff, just because it's old and original. That's how people are.

clubman 

We've been around this block a few times. For example, in the early 90's, I was hammering in rush hour and snapped a Shimano Arabesque DS crank in the middle of the arm. The crank wasn't that old back then and I could have died on that one. Turns out there was a void in the middle of the arm, invisible to an inspection. That's a very popular crank that many members have owned and ridden for decades without issue so what to do? It's kind of foolish to slap a 'DO NOT USE' hashtag or sticky on these parts based on one persons experience. The internet tends to blow issues out of proportion.

There's really a very short list of parts that are considered dangerous by this vintage group and they've been mentioned. Fortunately, most bike problems give notice when things start to go south. Catastrophic failures are mostly rare.

The mods here have good judgment and run a great forum. Go with it for awhile before asking for changes?

Maohaus

I am not arguing or insisting anything from BF or its members. Just suggesting. I won't make that mistake again.

clubman 

No flags on the play. You were polite in asking and no mistakes were made. It's hard to get a sticky...

Road Fan

Do you want to know about parts that are guaranteed to fail, or parts which have ever failed? If it is known that a few examples of a part have failed, how is that information useful? Even famous "death forks" have probably not all failed.

If you think there is a probability threshold that is useful to draw a line, how do you set that threshold and how do you know if the set of all example is in the "death" category?

I would just like to know how you see this working.

Trakhak

Maohaus makes a good point. Some of us who have been around bikes for many decades know about Viscount forks and Pivo stems and '60s/early '70s small-diameter French and Italian stems and Campy Record cranks and so on. (And at that, when a photo of a sagging French drop bar was posted a few years ago, the majority of C&V regulars refused to believe that it hadn't left the factory in that condition.)

Some of the veteran posters haven't been C&Vers long enough to have learned all there is to know on that topic, though, and there are frequently newcomers to C&V bikes who visit the Classic and Vintage forum for the first time. A sticky on the topic could, indeed, literally be a lifesaver, as Maohaus says.

There are currently 11 stickies in this subforum. Seems the bar to get a sticky stickied might not be impossibly high. But if 11 is the limit, I think it's possible that we would all survive the jettisoning of the "Post pics of you and your bike!" sticky.

Road Fan

I always thought that the solution (or at east an improvement) to the bottom slot stress riser was to drill a round hole at the top end of the slot to make sure the stresses due to outward bending are less concentrated than at the original small radius at the top of the slot.

So is it a death stem without an added radius and a safe stem with a radiusing?

Similarly Campy crank arms which have had some failures on sharp edges near where the arm transitions into the socket eye that contains the square taper: an commonly discussed fix was to make a radius with a mill file, Dremel cutter, or a strip of emery cloth, to de-focus the stress concentration.

Trakhak

By the way, Mauhaus, I suggest posting your suggestion here, where it will be considered by the people who are in a position to act on it:

https://www.bikeforums.net/forum-sug...er-assistance/

Wildwood 

Swaged cranksets reportedly not as strong as forged.