Cyclist died after relying on rear brake on Dales descent due to failed front brake

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thelawnet
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby thelawnet » 10 Dec 2020, 10:40am

Brucey wrote:
Ride-sleep-repeat wrote:....The article states he was an Engineer so surely changing disc brake pads shouldn't have been a problem for him....


clearly it was (for some reason), else he would have got on and done it?

One can only assume that at least part of the reason why he didn't get on and fix his brakes was that he didn't feel able to do so; it is not for everyone. Cable operated rim brakes have a much more obvious function and folk find it easier to repair/adjust them vs hydraulic brakes. You can buy new brake blocks that will fit most rim brakes in any bike shop and lots of other non specialist shops (eg supermarkets, wilko etc) too. Disc pads exist in mind-bending variety (for no good reason that I can see) and most bike shops only stock a few of the many possible types.


There appear to have been several issues:

* possibly unusual brakes such as are fitted on cheaper e-bikes which could be more difficult to change the pads in for some reason
* bleeding is not possible without special kit and fluid (some of which is highly toxic)

'No brakes because of no maintenance' is a common feature on bikes of all types. A lot of rim brakes end up without brakes through simple action of being parked with other bikes and getting tangled up. I think this is less likely with hydraulic brakes?

Also you end up with brakes that are missing noodles, where the cable has come out of the barrel, or where the cable has come out of the frame, and for this reason there is no braking force. Quick release mechanisms might be open, and numerous other faults.

Centering rim brakes is not easier than fitting disc pads, but there would certainly be an advantage for cyclists who have familiarity with cable systems in that they might be familiar with that.

My wife has taken a (rather nasty 7-speed hybrid) bike into "word corrected to Halfords" and they demanded £120 and a full change of everything - they refused to fix the rim brake. Since she has no idea how to do even basic maintenance she had only one brake. I fixed it myself for a new noodle or something like that, but in general almost any brake is impossibly complicated for many people, who will take it to the shop for a very minor issue, so it's difficult to distinguish them on this ground, except perhaps that 'zero maintenance' sealed systems may not offer sufficient braking force on such descents, so won't be great there either.

I don't believe that it's common or routine to advise on basic tasks such as removing wheels and fitting brake pads, which for disc brakes are IMO easier than many rim brakes, but perhaps it should be.

I'm not really convinced that a system that has run dry of fluid is much different from a cable system where the cables are not working for whatever reason. It all comes down to maintenance which many bicycle owners don't do any of....

It is possible in THIS case, that the cyclist was capable of maintaining some older system (ignoring that Shimano had hydraulic brakes in the late 1960s, they weren't common), but not this one, but we certainly don't know it for sure, and it doesn't really help the millions who want nothing to do with internal cables, housing stops, ferrules and all the rest of it, any more than they want to deal with hydraulic lines.

Brucey
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby Brucey » 10 Dec 2020, 10:52am

re the 'run out of fluid' diagnosis. If the fluid has leaked out of the system it makes a mess and is fairly obvious. Other than that there are only two reasons for a hydraulic system to 'run out of fluid', being

a) pad/disc wear causing the brake pistons to travel more than normal, so the quantity of fluid in the MC reservoir isn't sufficient , and /or
b) the quantity of fluid in the MC reservoir wasn't sufficient from the start (fault in design and/or setup; I've seen both)

It is quite normal for a MC reservoir to seem low on fluid when the pads are worn. However it is very common that there simply isn't enough fluid in the system from the start; it is 'so simple' that even people who do this stuff for a living (and know it is a safety issue) screw up.

cheers
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thelawnet
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby thelawnet » 10 Dec 2020, 11:05am

Brucey wrote:It is quite normal for a MC reservoir to seem low on fluid when the pads are worn. However it is very common that there simply isn't enough fluid in the system from the start; it is 'so simple' that even people who do this stuff for a living (and know it is a safety issue) screw up.

cheers


All possible though hydraulic brake pistons are generally designed to go out as they wear so the problem is that the brakes DON'T seem worn when in fact they are worn down to the backing plate, because they have self adjusted , which is good for consistent performance without adjustment but not good if you don't check pad wear.

In this case however the deceased was fully aware that the brakes were faulty before setting out, so whatever the exact cause of this fault isn't really the main issue e here

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horizon
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby horizon » 10 Dec 2020, 11:13am

thirdcrank wrote:For anybody thinking about the stable door, I can see only two broad approaches:-

An MOT-type régime for pedal cycles, or at least ebikes.

A compulsory system of wear warnings built into pedal cycles / ebike brakes with a fail-safe immobilization system for those who, like the deceased, were ready to continue with brakes they knew to be dodgy.

Before anybody jumps on me, I'm not recommending either approach.


(Not jumping :D )

OK, not an MOT but a half-way house where vouchers are freely given out to both adults and children to take their bikes in for a quick safety check at the LBS. I would have thought that owners (including Halfords) would jump at this as extra work is inevitable. I'm of the opinion that you shouldn't have to touch your own bike mechanicals if you don't want to but you do have to take it in on a regular basis (preferably for the complete strip-down, put back).

So a new mantra: hands, face, space, brakes?
When the pestilence strikes from the East, go far and breathe the cold air deeply. Ignore the sage, stay not indoors. Ho Ri Zon 12th Century Chinese philosopher

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Audax67
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby Audax67 » 10 Dec 2020, 11:16am

When our bunch did a week in Austria in 2007 we took along a few outsiders to make up the numbers and get a cheaper hotel rate. Our major climb of the week was the Kaunerthal, with a climb from ~800 metres up to 2750, with bits at 17%. Just as we got to the bottom of the climb one of the outsiders snapped a brake cable. He'd have been dead on the way down, no mistake. "Oh, it's not my bike" he said, quite unconcerned. He did stay down, though.
Have we got time for another cuppa?

slowster
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby slowster » 10 Dec 2020, 12:27pm

Nowadays many bike purchasers seem to fall into two different categories. There are those who try to fix any problems themselves, and even when confronted with unfamiliar technology like hydraulic disc brakes will try to understand how the system works and how to maintain them. And there are those who will tend to rely on their bike shop to fix any problems and keep the bike roadworthy, taking a similar approach to maintenance and servicing as they would with a modern car.

It's not surprising that a lot of new cyclists and especially e-bike owners seem to fall into the latter category. Some of the equipment now on bikes has changed so much over the last 20-30 years that anyone who last had a bike back then may find the new equipment much more involved to look after and adjust, and it often requires (sometimes relatively expensive) specialist tools. Add a battery, motor and electronic controls to a bike and the resulting e-bike is probably viewed by many owners as being too complex for them to maintain.

I think a particular problem with hydraulic brakes is that the unwillingness of many owners to learn to service and maintain the brakes results in their also not understanding how the brakes work. If someone does not have a good grasp of how they work, they will not understand the risks associated with the brakes, e.g. how the pistons will self-adjust and consequently how pads can become dangerously worn and how the hydraulics can be affected by air bubbles and water in the lines. Crucially they may also not therefore realise that if the brakes are not working properly, it is very likely that their performance will deteriorate even further until the point they will fail completely. In other words, they will not properly understand the risk they are taking.

Rim brakes do have a major advantage in these respects in that the caliper is much more exposed and it's much easier to see how the brake works, to spot a fault and to fix it. That is something which I feel is far more important in the context of safety theory, such as the Swiss Cheese model. Keeping designs and technology simple so that they do not require special knowledge, so that any fault is likely to be immediately visible, and so that the user can easily see and intuitively understand them, is a better approach than trying to incorporate extra technology in an attempt to reduce the risk/consequences of failure.
Last edited by slowster on 10 Dec 2020, 12:33pm, edited 1 time in total.

CliveyT
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby CliveyT » 10 Dec 2020, 3:35pm

slowster wrote:
I think a particular problem with hydraulic brakes is that the unwillingness of many owners to learn to service and maintain the brakes results in their also not understanding how the brakes work. If someone does not have a good grasp of how they work, they will not understand the risks associated with the brakes, e.g. how the pistons will self-adjust and consequently how pads can become dangerously worn and how the hydraulics can be affected by air bubbles and water in the lines. Crucially they may also not therefore realise that if the brakes are not working properly, it is very likely that their performance will deteriorate even further until the point they will fail completely. In other words, they will not properly understand the risk they are taking.

I was going to say how can people not understand the basics- it's how car brakes work after all ( and as an engineer I would have thought that he would have known about them), but then I remembered how many motorists I've had to point out they have a flat (and not just slightly underinflated, sufficiently that you can hear them coming).

rareposter
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby rareposter » 10 Dec 2020, 3:35pm

Plenty of people need to have it pointed out to them that their forks are facing backwards, their helmet is on back-to-front, their tyres are almost flat and so on.

pete75
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby pete75 » 10 Dec 2020, 4:04pm

CliveyT wrote:I was going to say how can people not understand the basics- it's how car brakes work after all ( and as an engineer I would have thought that he would have known about them)'


Knowing how car brakes work doesn't necessarily mean you know how to fix them.

tatanab
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby tatanab » 10 Dec 2020, 4:21pm

CliveyT wrote:it's how car brakes work after all ( and as an engineer I would have thought that he would have known about them),'
Please remember that the term engineer is much abused in this country. An electrical engineer might be the man who fixes your domestic wiring problems or maintains a works facility, or might be the chap behind a desk designing electrical systems in ships/aircraft - anything else. Only the last one is an engineer to our continental friends. This not to knock the unfortunate chap, only pointing out that his job is meaningless to the incident.

thirdcrank
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby thirdcrank » 10 Dec 2020, 4:28pm

Both multi-fatality coach crashes here involved the failure of recently "serviced" brakes. In the 1925 crash it was reported that the driver had taken a hammer to one of the brakes at the top of the hill before the fatal descent.

https://en.wikipedia.org/wiki/Dibbles_B ... rash_(1925)#:~:text=Dibbles%20Bridge%20coach%20crash%20(1925)%20The%20Dibble's%20Bridge,Seven%20people%20were%20killed,%20and%2011%20others%20injured.

https://en.wikipedia.org/wiki/Dibbles_B ... oach_crash

I'd forgotten but it seems the 1975 crash added to the campaign to have electro-magnetic retarders fitted to coaches.

From a cyclist's perspective, even with perfect brakes, the steep slope is the oblique approach to the bridge across the river; it's not the sort of hill where a fast descent helps get up the opposite side.

ChrisP100
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby ChrisP100 » 10 Dec 2020, 11:45pm

Given that the front brake normally accounts for around 70% of your stopping power it was a lot worse than 50% compromised.

Brucey
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Re: yet another disk brake thread

Postby Brucey » 10 Dec 2020, 11:56pm

peetee wrote:
Ride-sleep-repeat wrote:
Mike_Ayling wrote:A quick visual check of rim brake pads before you ride take a few seconds, disc pads are mostly out of sight out of mind.
Mike

Sorry but I disagree.It is no more difficult to check for wear on disc pads than it is rim brakes.The pads and rotor are easily visible.


That is entirely dependent on which bike you have. Some are only visible from below and turning some electric bikes over is not for the faint-hearted. Add in a few days grime and it becomes even harder to see how much pad is left.


I agree with peetee. Also pad wear is b-obvious to anyone using cable-operated brakes (of any kind), because the brakes will need to be adjusted. It is (by contrast) in one key respect pretty much counterproductive, safety-wise, to use hydro brakes because they self adjust for wear. In LBSs if someone brings in a well-used bike with hydro discs on and mentions 'they are a bit noisy' , the mechanics are already mentally placing the order for new pads and discs, because nine times out of ten the pads will have worn to the backing and then taken the discs out too. In a few cases the rider will have figured out what the problem is, but they didn't notice anything was happening until the pads were down to the backing.

Another evil thing (which can kill you) is that some disc pads are simply unreliable when they are worn past the manufacturer's limit. Pads are normally 4mm total thickness, typically comprising ~1.6mm steel backing and ~2.4mm friction material. I don't think any manufacturer recommends that you wear more than 1.5mm off the pads, and most suggest that if they are worn by more than 1mm when the bike is inspected, now would be a good time to change them. There are several reasons for this mandate, not the least of which is that when the remaining friction material gets to be about 1mm thickness, it can suddenly delaminate from the pad backing, and be lost instantly (by contrast if this happens when the friction material is less worn, the friction material tends to stay in the caliper for a little while at least). With cable operated brakes the result of delamination is 'no brakes'. With self adjusting hydros, 'no brakes' until they have been pumped a few times, and if the system is a bit short on fluid (as many are) then it is 'no brakes' again.

these are the same brakes as allegedly competent folk struggle to set up properly, that come out of the factory without being correctly filled with fluid, that give no clue that the pads are worn close to the backing unless you get on your hands and knees and conduct some kind of a forensic investigation.... how can you not apportion at least some of the blame in this direction? IMHO it is tantamount to giving little children loaded guns to play with and then blaming them when they blow their heads off; 'accidents' are inevitable....
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horizon
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby horizon » 11 Dec 2020, 12:33am

ChrisP100 wrote:Given that the front brake normally accounts for around 70% of your stopping power it was a lot worse than 50% compromised.


A passing thought: we (or I certainly do) see the braking system on a bike as comprised of two brakes that together provide the correct stopping power required. However, AIUI, the double system is also the fail safe: if one brake fails unexpectedly, there is always the other, even if it is only the back brake. This is fundamental to the braking system. But many people might not see it that way - you have two brakes because that is what a bicycle needs to stop. But you could argue that really you only need the front brake and the rear is your back up for when the front fails. As I see it, if the bike requires two brakes in normal use, there might be a case for adding a third as a fail safe. Somewhere there is a thread in which Brucey (or someone else) suggests that you should never change both brake cables from the same batch as both could be fatally flawed (e.g. the end barrels may snap off). So anyway, which is it - a bike has two brakes to stop the bike or a bike has two brakes in case one fails?
When the pestilence strikes from the East, go far and breathe the cold air deeply. Ignore the sage, stay not indoors. Ho Ri Zon 12th Century Chinese philosopher

Pete Owens
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Re: Cyclist died after relying on rear brake on Dales descent due to failed front brake

Postby Pete Owens » 11 Dec 2020, 12:52am

ChrisP100 wrote:Given that the front brake normally accounts for around 70% of your stopping power it was a lot worse than 50% compromised.

If you are going down a steep hill then your weight shifts forward even more than braking on the flat so your rear brake is not going to contribute significantly to slowing you down - though it can cause you to skid. Actually, the same also goes for emergency breaking - the maximum braking force is not limited by friction, but the point at which the rear wheel starts to lift when the back brake contributes nothing.