Every part on a bicycle is safety critical | Hacker News Reader

Every part on a bicycle is safety critical

escapecollective.com

77 pointsspooky_deep75 comments

There are a couple of extra factors to consider:

1. Does the part give clear "warning" that failure is imminent (e.g. sound, feel, appearance), or will it just fail suddenly? (This characteristic is often a key design feature of safety-critical equipment)

2. When the part fails (note, different failure modes should be considered separately), what is the range of outcomes? (E.g. drive failure is dangerous if you're crossing the street, not so dangerous at other times; bell failure could occur at the worst possible time, etc). Then on the other hand we have structural failure of the frame and handlebars etc which are almost guaranteed injury.

So if you are riding a bike with lightweight racing components that aren't designed with a "leak-before-break" philosophy, riding in mountainous terrain in a crowded peloton, then yes - pretty much any small deviation from normal could cause a massive pileup. On the other hand, a leisurely commmuter ride on a quiet path has much more tolerance for component failure.

it still depends what component it is, when I was a teenager I was riding a bike with rim brakes, the bolt holding the front rim brake to the frame broke all of a sudden during very light braking, the caliper rotated and got caught between the spokes and the front fork leading to the front wheel immediately stopping leading to me performing a superman dismount (since then I've ALWAYS worn bike gloves when riding). There had been no signs at all that the bolt was about to fail.

In my experience (many years of riding, quite a few years of bike commuting full time included) most mechanicals on the front wheel mean a fall/crash, but everything else just leads to having to walk home if you don't have the right tools (carrying a couple spare chain links in addition to the typical flat repair stuff and a full set of hex keys lowers the chance you'll have to do so).

> drive failure is dangerous if you're crossing the street, not so dangerous at other times

As TFA states, it depends on how much you're relying on it to keep balanced.

I think this depends a lot on the rider and their level of experience (just like it does with drivers). Modern ICE cars are so quiet (to the point that many cabins feature ANC to help mask engine noise) that you'd never be able to hear a whining belt or misfiring spark plugs, and perhaps not even squeaking brake pads. Bikes are similar but the rider is much more directly connected; even so, many riders are pretty oblivious to how they work or how to fix problems.

I don’t think automotive anc is typically that sophisticated. It plays certain fixed frequencies based on speed, load, etc. You can still hear mechanical issues especially higher frequencies which aren’t masked at all and a misfire typically causes a noticeable roughness, but that would be detected by the computer is most instances.

Sudden catastrophic failure is of the reason carbon fiber mountain bikes are a dangerous development.

Modern mountain bikes live in this weird consumer space. They are designed to stand up to incredible stresses while remaining light and agile. But they're increasingly purchased by people who don't really need high performance gear, they just like the idea of owning "the best" stuff.

I imagine the same thing is true with pickup trucks. What once was utilitarian becomes a vanity object. Now it's harder for people who genuinely need the performance.

And "the best" for those people is definitely not a mountain bike. But I'm sure it's the same factor as for SUVs, it looks cool and is big and scary. Pretty much everyone would be better off with a citybike and a decent geartrain + wheels

Horses for courses. The sort of person riding a high end mountain bike is not using it to buy groceries in the city.

>What once was utilitarian becomes a vanity object. Now it's harder for people who genuinely need the performance.

The bike space is full of people screeching about how you'll catastrophically break stuff if you use your bike for all its worth, just like the vehicle space is.

Regarding #1, on mountain bikes, carbon handlebars don’t give any warning before breaking. I quit using them after seeing one that broke on a friend’s bike. That could have been catastrophic.

One thing to know about torque wrenches: it’s actually more important that they are consistent rather than having absolute accuracy. (for the most part) why is this? If you have four bolts tightening down a handlebar into a stem, using a torque wrench correctly ensures consistent clamping load and avoids creating a stress point.

Whether those four bolts are at 8.86nm or 7nm is not usually a big deal. This is strictly speaking about bicycles, however, not aircraft or rockets :) there are a few bolts where an absolute clamp load on a single fastener is important: controls on a carbon bar. For my experience, though I have seen some bike shop mechanics reef on these (8-12nm) without consequence, even though the manual clearly states 4nm. I would do exactly what the manufacturer says here.

Modern bikes allow novel attacks too. I wrote a blog post about how to downgrade the firmware of a Shimano Di2 groupset and doing a replay attack to shift someone elses bike.

https://grell.dev/blog/di2_downgrade https://grell.dev/blog/di2_attack

this is why if I was a sprinter a the TDF I'd 100% be on a mechanical groupset (assuming the sponsors allowed me to) a missed shift on a sprint means losing 100%

You can use an electronic groupset as well. There are benefits to it. Shimano says it's not possible, but you can just connect the shift levers with a wire to the rear derailleurs [1]. They will not respond to wireless signals afterwards. I tried to do the replay attack and it failed. That way you get the best of both worlds.

[1] https://bettershifting.com/installation-guide/connect-12-spe...

> https://grell.dev/blog/di2_attack

> must be within a couple of meters of the bike

The range of radio transmitters/transceivers can be increased, and accidental transmissions from various things could affect it.

Choosing to allow any kind of remote control over a manned vehicle is a risk. There can be benefits, but winning a race may not be worth giving up your life.

Similarly, I don’t want IoT devices and won’t connect them when I have to buy them. I’d prefer to keep my thermostat and appliances safe, and a neighbor can turn them off if I forget.

Right, I agree. I think it is just lazy from the manufacturers to not wire the shift levers to the derailleurs. It should have a similar weight because you need additional cables but can get rid of the batteries within the shifters. Your main battery will last about 50% longer too. The only downside is the added work to wire them when assembling the bike. After that you can pretty much forget about the wires though.

Once I had the proper tool, I wired mine. They are all internal so I don't think I'll need to replace during the lifetime of the bike.

OP is probably not wrong, but also the article sounds a bit like written in the Final Destination universe.

I've been on two wheels long enough and have enough titanium in my body to know this shit really does happen

I can imagine handlebars breaking or a wheel suddenly coming loose or a mechanical gearshift just ripping off because you were a dumb teenager and didn't realize that switching while going uphill is a bad idea. (had the pleasure of the last two)

But seatposts "apple-coring" riders through the saddle? What?

Or the chain springing out of the gear just while you're climbing uphill on the wrong side of a road next to busy traffic, and the sudden jolt throwing you off balance and making you sway into the traffic?

I have lost a chain twice on motorcycles! Can definitely be sketchy if you don't react immediately.

And the seatpost thing is one I've heard about - IIRC Peloton had to recall several million stationary bikes because of a similar failure.

Ouch... wouldn't have thought, but thanks for telling.

I had a crank arm snap in half as I was powering up a hill. Got so thrown off balance, I crashed into a parked big rig. That was the lucky outcome

Pretty much all wheeled vehicle safety commentary on the internet is written by people who live in the filter bubble from that universe. Most everyone else rolls their eyes and continues on with their day.

This undervalues how much it depends on context, how and where you ride. Cycling is varied.

My casual rides to the shop on my beach cruiser in my sleepy little town? Both my wheels could come off and I'd probably be fine. I'm rarely hitting 10mph.

Downhill mountain biking? Yeah, basically everything is important.

Aside, I was expecting an article comparing good software to a bicycle. Every part of good software being important and well maintained.

Yes, this article seems to be about racing bikes.

Or commuting in locations without good infrastructure (which is almost everywhere). That exposes you to both velocities and traffic that can be seriously harmful.

Downhill mountain bikers basically expect their bike to be destroyed and train to bail and are dressed for impact. Road cyclists wear no protection other than some thin skimpy lycra and don't fall often but when they do it can be catastrophic.

The basics are as simple as ABC (Air, Brakes, Crank/Chain/Cassette) and on some newer bikes, a Q (Quick releases):

https://bikenewportri.org/abc-safetycheck/

There is also a certain matter of training --- badly bent a frame when I was young because I wasn't taught how to deal with a brake failure (rainy day and steel rims) --- the answer of course is to put one's foot up on the front wheel:

https://bicycles.stackexchange.com/a/7287/7344

Of course, the biggest danger could also be addressed by training --- as a part of getting a driver's license, drivers should be taught the "Dutch reach":

https://www.theaa.com/driving-advice/safety/dutch-reach?msoc...

and riding a bicycle a mile or two in practice and a use of/review of hand signals should be a part of the road test.

I think the chain slipping off the cogs is one of the most concerning failure modes because it tends to happen only under heavy acceleration, e.g. to dodge traffic at a busy intersection. Everything can seem fine and then you're stranded without power exactly where you need it most. It's worth regularly checking for wear and correct adjustment.

OTOH you just stop, get out of the bike and finish crossing the intersection by foot.

Can confirm: my chain snapped cycling along Princes Street, and I couldn't wear trousers for about ten years. Turns out that sliding down the road isn't very good for the skin on your knee.

Most frustratingly: I'd already ordered a replacement, it just hadn't arrived yet.

Do you have an idea what happened? Was it a "factory" failure that you couldn't have seen coming, or was it due to something like the chain being very old and worn out?

The tram track situation on princes street was outrageous.

This piece seems ignorant of regular people's realities. Many people cannot afford the luxuries of this elusive fancy "safe" bike with well-engineered parts, kept on a professional maintenance schedule. I suspect this really isn't an issue for most HN readers, and the fear-mongering just heats simmering angst. Remember a cure for angst is to 1) ride your bike and 2) donate time and resources your local bike repair cooperative or homeless shelter.

Author seems to forget the most important part of the machinery is the rider. What a glorious machine! He also seems to forget that millions of people in the world are riding bikes, motorbikes, and cars scrapped together from whatever they can afford or find. Forced to accept the risk, they usually get where they're going. I wonder does the author check out the maintenance of every Uber he hops into? "Let me see your torque wrench!?"

I've built and maintained all my own bikes since around 2005 with no training. It doesn't take a genius or a torque wrench to keep a bike rolling. I recently dropped my standards quite a bit on two bikes: One where I took a decent 2021 FS trail MTB I'd maybe ridden ten times on a black diamond downhill singletrack and another where I took a 1998 HT MTB with seized shifters, no grips, crusty, barely-functioning brakes and a sun-baked Hellraiser-looking rear tire held together only by a thin sheet of kevlar(?) around the streets of Portland, Oregon for three weeks wearing no helmet. I know, I'm a monster.

As an aside, I ride a 2005 Yamaha YZ250 (dirt motorcycle) my ex maintains... that feels sorta... dangerous.

I think the key is most people are ignorant. If people knew how to maintain such a simple thing as a bicycle, they would maintain them correctly.

Cost is mostly a non issue for most people. It doesn't cost a lot to maintain a non high end bicycle if you do it yourself. If you look at the shimano groupsets on the lowest end of the spectrum like shimano tourney, you quickly realize they need much less bicycle specific tooling as the high end ones. For example instead of socket bolts they are using hex head bolts that can be torqued with simple wrenchs or a single adjustable one. The 2 only specific tools are the threaded cassette tool and the square taper bottom bracket extractor. Everything else can be done with a very basic set of tool and there is nothing super challenging.

I see each part playing a functionality role, instead of safety-related role. A broken functionality might cause a safety issue. but it is still a functionality issue. A rider could fall off when a pedal is broken. That's just an undesirable consequence of broken functionality. A broken functionality always means things not working as expected, and naturally causing unexpected results. Most unexpected results can be safety issues, unless it is a win of a lottery.

One of the surprising failure i didn't anticipate with bicycles was how little contact the tires made with the road..

Even when the brakes fully work, the tires don't provide enough traction to stop quickly ...

Ever since that last big crash I am way more cautious about all the ways my bicycle can fail me while riding.. the one good thing is there aren't that many parts to worry about with bicycles

I'm sure you know this but a lot of people don't: if you want to stop quickly, use the front brake while adjusting your weight backward. The rear wheel can skid along a good distance, but if you apply the front brake to the point of wheelie liftofff but no further, that's as fast as you'll stop.

Aside from just laying down and scraping yourself against the rode, which might still be preferable depending on the alternative!

(Gravel or other slippery surface where the front wheel would just skid? You're toast. Ride slowly instead.)

Moreover, a lot of casual cyclists don't use the front brake at all -- evidenced by the condition of the front and rear break pads on bikes I've worked on. I think that effective use of dual braking is vital to safe riding.

I advise beginners (yes there are a lot of them) to practice making panic stops in a safe place such as an empty parking lot.

A panic stop while turning is a sure way to get a face full of asphalt even for seasoned riders. Don't try that please.

Edited per your suggestion.

I've been riding a fixed gear in traffic daiily for 14 years and it has never actually been necessary to panic stop in that time. I have a front rim brake and only use it on the big hill.

As a hypothetical one would think it would be necessary to slam on the brakes more often, but the situation has never come up.

I think the more you cycle the more managing speed becomes a function of predicting traffic around you than needing to react to unexpected things. Rarely an obstacle in your path is truly "unexpected" if you're able to understand how other participants in traffic will move.

It's come up often enough for me, in 55 years of riding.

Experience does make a difference, but I haven't yet seen the risk of an unexpected stop drop to zero. And I think learning to control the bike is still valuable for a beginner, so they can survive to the point of developing their street smarts. A panic stop teaches you how to control the bike.

The recent e-bike boom has been a chance to observe a lot of beginners learning to ride. One habit I've seen on the paths is being "afraid to stop," resulting in minor collisions within groups of cyclists, and cars making panic stops when the bike paths cross roads. These are the people to whom I suggest learning how to use the brakes.

I've used to commute in inline skates in traffic. It wasn't usual but I had a couple of close encounters.

The was an avenue with bike preference in the leftmost lane, but as cars parked anyway it way like a 1/4 lane.

Once I was completely zoomed out and felt something was off. The car at my right just push the break.

I followed along with a t drag and straighten up to get a clearer vision. A truck was turning left from the middle of the avenue, cutting 2 lanes including mine.

These things always happens in downhill. I had not enough space to brake. I turned left almost, not without almost hitting a woman that was waiting to cross the street 2 steps down the curb, and headed full blast too a cobblestone street. I don't know how I manage to do that without falling.

Yes a less experienced me would have not seen the risk early enough nor had the skills to get that turn. But there are shit you cannot predict.

Both you and your sibling commenter have read "rarely" and have chosen to interpret it as "never", which is not what the word means. :P

The parent comment you built off of used "never"

I'm not sure if it's me or you guys that are misreading that post but I interpreted it as "I never had to", not "nobody ever had to".

In context, they are clearly saying that beginner cyclists should not have to panic stop because it is exceptionally rare, as evidenced by their 14 years without needing to do it. It is extrapolating from their singular, personal experience to general frequency for the population. It is equivalent to saying "people shouldn't worry about breaking bones because I've never broken a bone." Even if you qualify the statement by saying "maybe someone out there has broken a bone at some point" you are still making a statement about it's rarity that can not be adequately supported by your personal anecdote. Having multiple people in a single thread which has been viewed by a few thousand people at most who have counter examples should clearly indicate that "it hasn't happened to me" doesn't equate to "you shouldn't expect it to happen to you."

Maybe I'm more charitable in my interpretation, but I don't really see grandparent making a generalization, they're giving a counter-example to requiring everyone to practice panic stops.

His and my reply assert that panic stops are not a panacea of avoiding traffic problems, but a side-effect of not paying more attention.

And cheers, this is my last clarification. I don't enjoy engaging with such excessive pedantry.

And tense your arms muscles and hand grip when you brake. A lot of over the handle bar accidents are due to people not being ready to absorb the force of braking.

Also, on uneven ground you can apply a little brake to get a sense of the surface. Feel how the bike responds and moderate accordingly.

> Gravel or other slippery surface where the front wheel would just skid? You're toast. Ride slowly instead

Yup! Can't stress this enough. The last big crash was literally slippery road and a speed bump. The bicycle did a full 180. I'd have probably been better off if i just didn't brake at all... Didn't notice the speed bump in the darkness and when i suddenly did The front brake was on, the bike hit the speed bump after skidding.

Being lights, bicycle have very efficient braking on the other hand. The thing is most people never train to brake in an emergency so don't know how to modulate them correctly nor how to stay upright even if you lock them up.

That reminds me of this funny comment https://www.youtube.com/watch?v=99wJn5QBvyg&lc=UgysqlxliZXq-... "Find someone who trusts you as much as this man trusts his tires"

1) avoid nockoffs of seat posts, stems and handlebars. Well known 2) A worn front chain ring won't negatively impact a rider. 3) it is a bicycle, not a helicopter. 4) Fear mongering is unnecessary 5) A torque wrench needs to be consistent. so long as it is within 10% you are fine 6) sounds like a bike shop owner trying to drum up business.

He’s a cycling journalist (specialized in tech), not a shop owner.

I was trying to reinstall my rear wheel the other day after removing a bike trailer. I apparently didn't tighten it down enough and the wheel came out of the brackets as soon as I started to ride, causing an instant crash and a lot of bruises.

Things like that make me feel apprehensive about trying to learn more bike maintenance stuff myself. It's almost inevitable to have to patch flat tires though so you're always going to be reinstalling the wheel yourself, but I don't touch the brakes even if it seems like an easy fix.

This is my biggest fear when working on my bike. I tighten those with that fear in the back of my head constantly. I have to be careful not to over-tighten them because of this.

Regarding the tires. I don't know if it messes with how you ride or anything, but we have the tire slime in all of our tires and we keep a portable Ryobi electric bike pump with us when we go on trails.

Brakes suck. For maintenance I actually enjoy the regular brakes instead of the hydraulic ones. You have to realistically change your break pads every month or two and it's difficult to do with the hydraulic ones by comparison.

What are you doing that you're changing brake pads every couple months?

For non-cyclists: brake pads have a minimum thickness, and usually a wear line molded in (less common on disc brakes). If you've got enough pad material and it isn't glazed or contaminated, it isn't time to change them yet. They can last years. I've got maybe 6,000 miles on the pads on my road bike, and they're fine.

The only normal case for needing to change pads every couple months that I've run across is people riding lift-service downhill. In which case, buy a set of digital calipers and check your rotors regularly, because they have a minimum thickness too.

For reference: I am a bike mechanic, though not a paid one at the moment.

Just to add some context: e-bike commuters in a hilly city would go through the stock organic brake pads in <500 km sometimes. Could be as little as 6 weeks. The shop I worked at (back in the day) would replace them with longer wearing third-party pads.

> What are you doing that you're changing brake pads every couple months?

If you do mountain bike / cyclocross you can get through a set of pads in one weekend if it is muddy and involve a lot of downhill. Mud can be super abrasive depending on the kind of soil you are riding on.

On the other hand you should learn bike maintenance so you can check and anticipate any failure. Fixing brakes is not rocket science.

Topical, with RAGBRAI just around the corner. I'm constantly awed at just revolutionary the bicycle seems to be from an industrialization perspective. To me, bicycles and smartphones are two real thick lines to draw on when the world became something different.

I definitely had some failures that didn't really influence safety but were serious enough. I lost one of the pedals during a hike and still came back home on this bike. I guess it depends on what you do.

Speaking of which. Last week I parked my bicycle against a car. The owner got angry at me, which I don't understand, people park their bicycle against my bicycle all the time. And by doing that, it is far more likely that safety critical parts are damaged.

Does your bike not have a kickstand?

Yes, but the slightest amount of wind will make it fall and this is certainly not unique to my bicycle. It is better to leave a bike in a more stable position.

Turn your handlebar all the way to the right side (assuming the stand is on the left) and it will be much more stable.

Just because you bought a wrongly-sized kickstand for your bike doesn't give you the right to damage people's cars.

The kickstand is an integrated part on most bicycles, and yes they are often undersized. However, like I said, people think it is normal to park their bicycles against mine, so why should it be different with other vehicles like cars?

Because a car isn't a bike.

Do you think people should treat cars and bikes 100% equivalently (including such things as whether you can drive them in the bike lane), or would you agree society should treat the two differently?

Depends on the circumstances. When it comes to surface scratches caused by the parking of other vehicles they can be treated equally.

PS: your argument is a bit silly. Analogy: all humans are equal; except that does not mean that we should treat all people the same way in all circumstances.

> When it comes to surface scratches caused by the parking of other vehicles they can be treated equally

So you're saying if a stranger damages your bike, that gives you the right to pay it forward and damage some unrelated stranger's car?

Putting a bike standing against a car doesn't damage it. Typically the only parts that touch the vehicle are saddle (soft material) and handlebar bar tape or grip (again, soft material).

Reply on news.ycombinator.com