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kerley - Member
The only way to stop quickly on a fixed gear is skid stopping (lots of little skids not one long skid)
There is no way to [i]stop quickly[/i] without brakes! Period. Especially on a track bike with a short wheelbase and very hard, very narrow tyres. It may be possible to optimise the no brake retardation but it'll still be shocking compared to even a single front caliper. All you're ever going to do is slither down the road in a barely controlled tank slapper.
Please stop perpetuating the myth.
Apologies Bez, I didn't trawl far enough
[url= http://web.mit.edu/cwarner/www/FixedGearSkidSample.pdf ]Nice study on skid stopping from MIT[/url]
Comparison to previously established skidding models show the stopping distances average 5.8 ± 2.1 times than the model of the back-wheel locked skid
and
From these comparisons, it appears one needs to have at least some sort of front-wheel stopping mechanism in order to come to a sufficiently quick stop
It's not going to end well.
[b]The only way to stop quickly on a fixed gear[/b] is skid stopping (lots of little skids not one long skid)
No it isn't the [b]only way[/b]
It's the wrong way. The right way is to use your ****ing brakes ffs.
Latest radio news report is that he was doing 14mph also that the bike was tested and shown to take 4 times as long to stop as a normal bike.
Christ it's hard enough stopping sometimes with two brakes sometimes let alone one! I am unsure of the law but surely two brakes must/ should be mandatory!?
I don't live in London but was down there recently, jesus the cyclists are terrifying! They go so fast right next to parked cars, which to me always means hazard hazard hazard! i.e people appearing from nowhere between parked cars and/ or doors opening. It's not like that in Edinburgh I have to say. From what I see driving in London is a lot more aggressive than other cities, making it super unsafe for cyclists and pedestrians.
I am unsure of the law but surely two brakes must/ should be mandatory!?
It is.
Latest radio news report is that he was doing 14mph
That's really not that quick, if you consider how it would be framed if it was a driver being the d!*k. "Mr Smith was driving cautiously at a mere 14mph when the victim stepped out in front of him".
@andykirk - Two working brakes is the legal requirement but a fixed wheel may count as one brake.
[url= https://www.wheelbuilder.com/downloads/VeloNews_June09_BrakeTest.pdf ]A Dura Ace 7800 caliper will generate a deceleration of almost -1g[/url]. The MIT study couldn't get remotely close to such decelerations in their study.
v^2-u^2 = 2as, so s = u^2/2a and that means distance doubles as deceleration halves. 14 mph is 6.3 m/sec, so a good caliper brake might stop in 6.3^2/2*9.8 = 2m. I suspect that this calculation plus Figure 5 from the MIT study (8m) is where the ratio of 4 fold comes from.
If the CCTV shows she stepped out in a distance that an ordinary bike could not stop at 14 mph, then the young man has a defense (probably his only defense).
From BBC news website.
The court has been told crash investigators had concluded Mr Alliston would have been able to stop and avoid the collision if the bike had been fitted with a brake.
The trial continues
I suspect that this calculation plus Figure 5 from the MIT study (8m) is where the ratio of 4 fold comes from.
More likely it's from the practical testing the police did with the bike at the Hogg Hill circuit last year.
News article suggests victim was 9 metres in front of cyclist when stepped-out ~ theoretically enough distance for even brakeless fixie to stop. Not looking good for the perp.
My experience of riding a fixed gear with a fast road bike group meant that I needed 2 brakes as you tend to start downhills slowly, but the greater momentum carried you faster / further at the bottom and I sometimes needed the brakes to not run into the back of the group on narrow lanes - reaching 70kph on a 68" gear means 200rpm+
It might not be just about whether he could have stopped, it might also be about whether he tried to stop.
In the case of a civil claim, people would be looking at who's responsible for the harm, and a pedestrian stepping out without paying attention to oncoming traffic and looking at their phone would most likely be contributorily negligent.
However, this being a criminal trial is more a case of is riding a non-complaint bike a reckless act and was this recklessness the cause of death.
Regarding the effectiveness of fixies at stopping. Skidding is not as effective as controlled braking, and braking with the rear is not as effective as the front, in fact on a dry road a good emergency stop the back wheel will be on the point of lifting off the ground so 100% of the braking effort is done through the front wheel. A good fixie rider might be able to stop as quickly as a crap rider on a crap bike but then again crap riders rarely go over 10mph and my conscience would never let me ever choose to ride a bike with no front brake on the road as I know with one I can certainly stop faster.
However, this being a criminal trial is more a case of is riding a non-complaint bike a reckless act and was this recklessness the cause of death.
It shouldn't be. Gross Negligence (in UK law, not recklessness) only applies if the negligent act was otherwise lawful. Riding a brakeless fixie isn't.
Unlawful Act Manslaughter is probably what they are trying to prove, which brings the relevance of the stopping distance (that the unlawful act of riding a fixie on the road directly led to the death).
The guide is at: http://www.cps.gov.uk/legal/h_to_k/homicide_murder_and_manslaughter/
It might not be just about whether he could have stopped, it might also be about whether he tried to stop.
Would an 'ordinary' cyclist, on seeing someone step into the road, stop, or slow, or swerve around them?
I got the impressioon that he had slowed and swerved, but that she either stopped or changed direction resulting in him still hitting her.
It might not be just about whether he could have stopped, it might also be about whether he tried to stop.
I seem to remember another pedestrian death in a collision with a cyclist, in that case he called out or rang his bell but didn't make any attempt (or enough) to avoid the pedestrian. He went to prison.
It shouldn't be. Gross Negligence (in UK law, not recklessness) only applies if the negligent act was otherwise lawful. Riding a brakeless fixie isn't.Unlawful Act Manslaughter is probably what they are trying to prove, which brings the relevance of the stopping distance (that the unlawful act of riding a fixie on the road directly led to the death).
Fair enough; so criminally negligent, rather than reckless. Either way it falls under the wider umbrella of involuntary manslaughter.
I got the impressioon that he had slowed and swerved, but that she either stopped or changed direction resulting in him still hitting her.
This seems to be the latest on that:
"CCTV footage played in the courtroom showed Alliston beginning to swerve as he approached Mrs Briggs at an average speed of 18mph - with crash investigator Edward Small saying she had stepped into the road 3.8 seconds before the crash."
[quote=ninfan ]I got the impressioon that he had slowed and swerved, but that she either stopped or changed direction resulting in him still hitting her.
It's all a load of speculation, but if that is the case then there's his defence right there.
Fundamentally, as with all the drivers killing people, it's going to be down to whether all parts of the prosecution case can be proved beyond reasonable doubt. All the defence has to do is find reasonable doubt in one part of it, even if that seems a relatively trivial part. I reckon if his lawyer can show a reasonable possibility of the death not occurring if she hadn't stopped/changed direction (if that's indeed what happened), then he'll probably get off.
martinhutch - Member
f they're seeking manslaughter then maybe they think he hit her on purpose?
Manslaughter doesn't mean that.
No reason why that scenario couldn't be manslaughter.
I seem to remember another pedestrian death in a collision with a cyclist, in that case he called out or rang his bell but didn't make any attempt (or enough) to avoid the pedestrian. He went to prison.
This one?
http://news.bbc.co.uk/1/hi/england/beds/bucks/herts/7496757.stm
I reckon if his lawyer can show a reasonable possibility of the death not occurring if she hadn't stopped/changed direction (if that's indeed what happened), then he'll probably get off.
he shouldn't get off - he was deliberately riding around without a front brake as he thought it was cool, and he knew the consequences as is shown by this quote :
In 2015, he tweeted: “The time when you first take your brakes off and feeling like you’re in a lucasbrunelle movie,” in apparent reference to an American bike stunt film-maker.
i.e. this was the type of riding he aspired to :
Actually it's probably this one
http://www.bbc.com/news/uk-england-dorset-25447028
I reckon if his lawyer can show a reasonable possibility of the death not occurring if she hadn't stopped/changed direction (if that's indeed what happened), then he'll probably get off.
With the emphasis being on his ability to stop I'm not so sure. "Stopped/changed direction" doesn't trump he should have just braked and pulled up to avoid the collision. Same as when you drive, you sound your horn, brake and swerve if needed. Not braking just assuming a pedestrian on hearing your horn will get out of the way won't cut it in court.
Not braking just assuming a pedestrian on hearing your horn will get out of the way won't cut it in court.
Especially if you didn't have effective brakes and therefore it could be argued that the reason for not braking was only because you couldn't.
@Horatio.The first link was the one I was thinking about. Got the going to jail bit wrong. I blame my age !!!
Not braking just assuming a pedestrian on hearing your horn will get out of the way won't cut it in court.
Did you read the example of the bus driver I posted earlier?
This one?
http://news.bbc.co.uk/1/hi/england/beds/bucks/herts/7496757.stm
If the reporting is accurate then he appears to have got off very, very lightly.
CCTV footage played in the courtroom showed Alliston beginning to swerve as he approached Mrs Briggs at an average speed of 18mph - with crash investigator Edward Small saying she had stepped into the road 3.8 seconds before the crash."
****ing hell, that's a long long time not to manage to stop - even accounting for the initial "must've seen me, they'll move out of the way" reaction. It does genuinely sound like if he was riding with anything like an effective set of brakes he would've pulled up quite comfortably - I was a little suspicious of the fixed wheel no front brake causing the accident thing when I first heard about it.
[quote=taxi25 ]Same as when you drive, you sound your horn, brake and swerve if needed. Not braking just assuming a pedestrian on hearing your horn will get out of the way won't cut it in court.
Except the context (as given by the quote at the start of my post) is that he did slow down and swerve, and this could have been sufficient to avoid the collision were it not for the pedestrian's subsequent actions.
Though as pointed out by Bez, an expectation of what another road user is going to do appears to be sufficient defence in motoring cases - as I pointed out, you simply have to introduce reasonable doubt in some aspect of the case, and it appears sufficient to show that the victim's actions were in some way at fault (referencing Helen Measures). Though I'm not sure if there is a difference here between the proof required for DBCD/DBDD and manslaughter which actually makes it harder to use such defences in manslaughter cases.
she had stepped into the road 3.8 seconds before the crash
So riding along at 18mph and a person steps out giving you 3.8 seconds to react and ultimately stop.
A lot of riders would not have stopped in time, brakes or no brakes
Don't go too hard on the numbers at this stage. Something is missing from reports, because the distances that have been given are covered in around 1 second at 18mph, not 3.8. Currently available details do not make it entirely clear what most of the distances/times relate to.
The chances of the expert reports being accurate are reasonably high, but we're not currently seeing an accurate and clear communication of them in the media.
I dunno if we'll see the footage, but this is all assumption without at least a detailed description of its contents.
Purely hypothetically, it can sometimes feel safer to steer around an unexpected obstacle than to perform an emergency stop.
Barfoot, under cross-examination by Miss Ascherson, said: “I saw her cross the road on the right and she was comfortable in doing that as she had enough time on that side of the road. ?“I thought she was going to stop in the centre but when I realised she was going to carry on I shouted, blew my horn and braked as hard as I could.
It seems like he sounded his horn and braked upon realising the woman was moving in front of him. He should have seen this earlier but didn't. The cyclist at the centre of this thread was riding a bike that didn't give him the braking option (according to the court). Anyway the case is on going we'll find out what the court decides soon enough.
3.8 seconds seems like plenty of time to stop to me. Can't find good info on bike stopping times but from 20mph on a motorbike it's supposed to be something like 1.8s to stop (including reaction time).
If the tests the police did prove something similar then the difference between say 2 seconds with brakes and 8 seconds (the quoted 4x from the tests they did) is going to be significant given that 3.8s falls almost midway.
There is no way to stop quickly without brakes! Period. Especially on a track bike with a short wheelbase and very hard, very narrow tyres. It may be possible to optimise the no brake retardation but it'll still be shocking compared to even a single front caliper. All you're ever going to do is slither down the road in a barely controlled tank slapper.Please stop perpetuating the myth.
So how I have been riding AND stopping for 10+ years is now a myth.
Out of interest, have you actually ridden a track bike with a low gear with a good level of experience in skid stopping?
Slithering down the road would suggest not....
So how I have been riding AND stopping for 10+ years is now a myth.
Correct.
philjunior - Member
CCTV footage played in the courtroom showed Alliston beginning to swerve as he approached Mrs Briggs at an average speed of 18mph - with crash investigator Edward Small saying she had stepped into the road 3.8 seconds before the crash."
**** hell, that's a long long time not to manage to stop - even accounting for the initial "must've seen me, they'll move out of the way" reaction. It does genuinely sound like if he was riding with anything like an effective set of brakes he would've pulled up quite comfortably - I was a little suspicious of the fixed wheel no front brake causing the accident thing when I first heard about it.
That was 3.8 from stepping out, no info on if they were visible to the cyclist or even on that side of the road. Or equally as in the other post about the driver, the rider might have assumed the person would stop in the middle of the road, so only shouted when they realised their paths were about to converge. We dont know.
Repeating the point about the lack of clarity in current reports: there has been no explicit mention of whether the cited times include reaction time, though given the numbers involved (and there are multiple reported values so this information, too, is unclear) I very much suspect they do not. If they do not then they need to be added. You may want to look up the sort of reaction times the police quote in prosecutions of drivers, but they're generally at least 1.5 seconds.
[quote=chakaping ]Purely hypothetically, it can sometimes feel safer to steer around an unexpected obstacle than to perform an emergency stop.
That's exactly the feeling I have with this case. Fundamentally you don't need to come to a complete stop to avoid running into a pedestrian in the road - I'm sure I've steered around a few and I'd be surprised if most people here haven't. I'm still assuming that the cyclist didn't intend to hit the pedestrian and that he would have avoided her but for her subsequent actions in the 3.8s after she entered the road. If that is the case, the defence of the bus driver is extremely pertinent - if he was expecting to avoid her and at the point he realised he wasn't he couldn't have stopped even with a front brake (as was the case with the bus with fully functional brakes) that completely removes the legality of his bike from the case.
That was 3.8 from stepping out, no info on if they were visible to the cyclist or even on that side of the road. Or equally as in the other post about the driver, the rider might have assumed the person would stop in the middle of the road, so only shouted when they realised their paths were about to converge. We dont know.
I see that from subsequent comments - and one would not reasonably expect every road user to stop every time a pedestrian steps onto the road on the other side of a traffic island.
So how I have been riding AND stopping for 10+ years is now a myth.
I don't think there's any debate about the fact that it's possible to stop a fixie with no additional brakes. But equally there's no debate about the fact that you can't stop it as quickly as you can if you add a front brake. You can ride for as many years as you like, you don't get to change physics.
Obviously reaction/thinking time is a factor before anyone could begin to apply brakes (providing they have them), but to state the obvious there is no substitute for good roadcraft and awareness. Flat bars are better for riding in traffic, but if you are going to ride a drop barred bike [edit - in a busy city centre type environment], then you should be able to brake without moving your hands on the bars, e.g. hands on the hoods rather than the tops of the bars.
Purely hypothetically, it can sometimes feel safer to steer around an unexpected obstacle than to perform an emergency stop.
This requires very good awareness of what is happening all around you, i.e. constantly checking, otherwise you risk swerving into the path of a car behind you.
'm still assuming that the cyclist didn't intend to hit the pedestrian and that he would have avoided her but for her subsequent actions in the 3.8s after she entered the road.
The problem for the guy in this case is that it can and will be argued that the reason he didn't try to stop was because he couldn't, and the reason he couldn't stop was because he was knowingly riding an illegal bike without effective brakes. It'll be argued that a forseable potential consequence of the latter was the former, hence the manslaughter charge.