Man who was paralysed sues Planet X for £10 million

[Ajax Bay]

I get the idea that it's to do with the compression plug and where the stem clamps on the steerer tube. But is it risky if they overlap so the stem is tightening from outside and the compression plug is expanding from inside at the same time; or is that desirable?
edit: I think I understand now; so the compression plug should be long enough to cover (most of) the length of the stem.

Think this weightweenies forum post is a great resume, with pictures:
"The most common types of damage to the steerer tube come from incorrect torque specs on the stem pinch bolts, [not just too tight]. Suprisingly just as often from being not tight enough. [If the stem is not tight there's movement which cuts into the steerer tube.] The other common type of damage comes from a seized up headset bearing that is not turning with the steerer tube and cuts into it.
"All that being said along with the number of recent posts on steerer tube failures, take the time to check your steerer tube, stem clamps and handlebars and make sure your expander plug is doing its job."

In image above, plug too short for the number (height) of spacers used above so stem clamps on unsupported (but it's not that simple).
There are (3) main purposes for the expander plug (aka compression plug):
1. Installation allows pre-load of the headset before clamping on the stem,
2a. Reinforcing the section of the steerer tube around which the stem clamps,
2b. Reinforcing the 'open' top of the steerer tube around which the stem clamps - where it's structurally weakest and prone to being crushed by the stem clamp (supports argument for a 5mm spacer, as well as having the top bolt bear down on spacer and not (cut) open end of steerer tube).
3. Reinforcing the steerer tube against the force of the rider's weight up and down on the handlebars (and therefore the stem).

 

[Deleted member 121159]

Think this weightweenies forum post is a great resume, with pictures:
"The most common types of damage to the steerer tube come from incorrect torque specs on the stem pinch bolts, [not just too tight]. Suprisingly just as often from being not tight enough. [If the stem is not tight there's movement which cuts into the steerer tube.] The other common type of damage comes from a seized up headset bearing that is not turning with the steerer tube and cuts into it.
"All that being said along with the number of recent posts on steerer tube failures, take the time to check your steerer tube, stem clamps and handlebars and make sure your expander plug is doing its job."

View attachment 715353
In image above, plug too short for the number (height) of spacers used above so stem clamps on unsupported (but it's not that simple).
There are (3) main purposes for the expander plug (aka compression plug):
1. Installation allows pre-load of the headset before clamping on the stem,
2a. Reinforcing the section of the steerer tube around which the stem clamps,
2b. Reinforcing the 'open' top of the steerer tube around which the stem clamps - where it's structurally weakest and prone to being crushed by the stem clamp (supports argument for a 5mm spacer, as well as having the top bolt bear down on spacer and not (cut) open end of steerer tube).
3. Reinforcing the steerer tube against the force of the rider's weight up and down on the handlebars (and therefore the stem).

Great information. Thank you.

 

[brommieinkorea]

Carbon Fibre is just a poor material for consumer goods. It requires regular testing with means not available to the average person. This is farther exasperated by production in Chinese sweatshops where quality control is spotty at best. The amazing part about this is that it isn't a daily occurence.

 

[Alex321]

Carbon Fibre is just a poor material for consumer goods. It requires regular testing with means not available to the average person. This is farther exasperated by production in Chinese sweatshops where quality control is spotty at best. The amazing part about this is that it isn't a daily occurence.

The fact it is a rare occurrence shows that it is in fact a suitable material.

 

[rogerzilla]

Carbon Fibre is just a poor material for consumer goods. It requires regular testing with means not available to the average person. This is farther exasperated by production in Chinese sweatshops where quality control is spotty at best. The amazing part about this is that it isn't a daily occurence.

In theory it's a very good material because it should have excellent crack-stopping qualities, as well as being strong and light. But everything can be "optimised" in the name of cost reduction, to the point where it's no longer fit for purpose.

 

[T4tomo]

I assume the original legal action with whoever was providing public and product liability insurance at the time to the old Planet X company is still very slowly lumbering on.

 

[Bonefish Blues]

I'm further exasperated by the Chinese sweatshops' tendency to exacerbate failures.

 

[bonzobanana]

Carbon Fibre is just a poor material for consumer goods. It requires regular testing with means not available to the average person. This is farther exasperated by production in Chinese sweatshops where quality control is spotty at best. The amazing part about this is that it isn't a daily occurence.

Carbon fibre failure is likely a daily occurrence even though they make up a small percentage of bikes sold because frames and forks do fail with time. Yes carbon fibre can fail dramatically without notice but other times you can feel carbon fibre failure or see it and just know its reached the end of the line. Lightweight performance road bikes are certified as short life products which is why Giant gives this warning in their manual. I remember Planet X not having their own manual without any info on weight limits etc and the warranty was only 2 years including the frame in the past. I feel like Planet X never took safety too seriously personally. I thought instructions were a requirement of the certification they certainly were for most products I dealt with as a compliance officer at a importer. Ultimately bonding a aluminium steerer to carbon fibre blades was always risky and difficult manufacturing procedure which is why many big brands moved away from such forks and they became more a staple of lower cost products like Decathlon, Pinnacle, Argos bikes etc who wanted to provide a carbon fork option at a lower price. I think Halfords don't supply carbon fibre blades bonded to an aluminum steerer nowadays but I could be wrong but the Carrera road bikes either have steel, aluminium or full carbon fibre forks. It should be pointed out Decathlon have lower weight limits for their bikes than many other brands so I guess you can make the case that there is less of a safety risk but I still see people on forums who seem to ignore weight limits of bikes and just assume they will be ok.

 

[Fastpedaller]

An interesting post above - Also, how many people read instructions? I guess the vendors are covering themselves if they provide instructions. I've seen many people who don't know how to use a wheel quick release and just twiddle it round until it's tight!

 

[Smokin Joe]

I've seen many people who don't know how to use a wheel quick release and just twiddle it round until it's tight!

I've come across several of them.

 

[Moodyman]

An interesting post above - Also, how many people read instructions? I guess the vendors are covering themselves if they provide instructions. I've seen many people who don't know how to use a wheel quick release and just twiddle it round until it's tight!

What is the correct quick release closure process for those of us who might not be doing it right?

 

[PedallingNowhereSlowly]

What is the correct quick release closure process for those of us who might not be doing it right?

The pressure required to close the quick release should be enough to leave an impression in the palm of the hand.
Also important to ensure the wheel is correctly seated in the drop out. Also better if the bike is on the ground with some weight bearing down onto the axle. Always worth doing a quick check before re-mounting the bike to make sure everything is seated correctly - for example apply the front brake and push down and forwards on the bars.

Of course, take this with a pinch of salt and defer to manufacturers instructions.

And thru axles for the win.

 

[HMS_Dave]

When i was a 25 stone rider, would anybody here have recommended a carbon fibre fork anything on a bike? Doubt it, and you probably know why if we're honest, but i had ridden 2 bikes when i was that weight, probably against the manufacturer recommendations (although one was an elephant bike) on steel and aluminium forks and they are both still going now im around 10 stone down. This is an extreme example and potentially CF could be made specifically for me to take that weight and a substantial cost, but it is not really realistic and i don't think i'd trust it and i personally wouldn't recommend it. Why anybody want's this on an all-terrain gravel bike is beyond me. I'd want proven reliability. Each have their own needs and wants i suppose...

 

[figbat]

What is the correct quick release closure process for those of us who might not be doing it right?

Ok, so some people simply use the lever to turn the nut until it’s tight. This is wrong.

The lever acts as a cam, in other words as it flips from one side to the other it pulls or loosens the skewer. What you should do is make sure the lever is on the ‘open’ or ‘loose’ setting, then spin it until it starts to tighten a little bit, then flip the lever over. If you got it right the lever will take some effort to move completely to the other side, the ‘closed’ side. If it’s easy to flip over then go back, spin a bit more and try again until you get the right amount of resistance.

There are also people who get uptight about which way the lever should be pointing when tight, for either safety or aesthetic reasons. Generally pointing backwards or in line with the fork is required. This presents the least chance of the lever getting caught on something and being accidentally opened.

 

[bonzobanana]

When i was a 25 stone rider, would anybody here have recommended a carbon fibre fork anything on a bike? Doubt it, and you probably know why if we're honest, but i had ridden 2 bikes when i was that weight, probably against the manufacturer recommendations (although one was an elephant bike) on steel and aluminium forks and they are both still going now im around 10 stone down. This is an extreme example and potentially CF could be made specifically for me to take that weight and a substantial cost, but it is not really realistic and i don't think i'd trust it and i personally wouldn't recommend it. Why anybody want's this on an all-terrain gravel bike is beyond me. I'd want proven reliability. Each have their own needs and wants i suppose...

Luescher Technik on youtube made the point that carbon fibre forks are a lot more dangerous than carbon fibre frames because forks failing means the whole front wheel detaching from the bike and the rider faceplanting onto the road with possible vehicles all around that could ride over the cyclist. A logical product would be a carbon fibre frame and steel forks as that would be much safer but the reality is the market is full of strong frames be it aluminium, titanium or steel with carbon fibre forks which are a far greater safety risk. However I understand from a performance, pricing and comfort perspective what we have makes sense but not from a safety perspective. I'm not a great fan of carbon fibre as a material anyway as its not recyclable and you need to be extra careful with it and its maintenance. Torque values are critical etc and if the bike falls over in the wind it could be written off if something smacks against one of the tubes. However I totally accept its still a good option for many especially lighter riders and the risks are low. I just like the idea of riding a bike that is safe more than riding a bike that is fast. Lower gearing compensates for any frame weight difference albeit with slower hill climbing. If you are a 90kg rider does it really matter that much if a carbon fibre frame is 0.5-1kg less than a much stronger frame? It doesn't matter to me. I've not every owned a carbon fibre bike though so I'm giving my opinion blind. All my bikes are steel or aluminium. Even my older Giant Defy has an aluminium fork, I think the next year they changed to carbon fibre but mine was the last with aluminium.