Guy on a fixie has only got fixed gear as brake, so his bike is illegal on the road. His stopping power will be limited - but not necessarily that limited, that will depend on gear ratio. But he's legally in the wrong.
A lady steps off the pavement looking at her phone*, approx. 6m in front of him. He's doing 18mph. His thinking distance at that speed is 5m - so before he can brake, before he can react, he'll be within 1m or not far from. He won't be able to stop, no matter what brakes he's got. At 18mph he's moving a shade over 8 meters per second - the whole time for the incident is therefore in the region of three quarters of a second. The time he's got to do something after around the 5m it takes for him to be able to react is the time it takes to travel 1m - at 18mph thats an eighth of a second.
He tries to swerve, he moves away from the traffic to try to go behind her. Obviously at the last minute when she sees him she jumps back too. The result is a tragic collision, and her wounds kill her.
He's prosecuted for manslaughter and killing by wanton and furious driving. He's found not guilty of manslaughter, guilty of wanton and furious, and is sentenced to 18 months. Being a fan of alleycat cycling vids, being tattooed, and going online and being unrepentant played badly for him.
The details of the event as I've put them are not, I think, contentious - indeed that's pretty much as accepted by both sides in court. So the questions arising are (1) could he have avoided the crash, (2) has justice been served and (3) within the context of other sentences, how does this fit?
So in order...
Could Alliston Have Avoided the Crash?
Well, maybe. Its very easy to sit here and say he didn't have any chance of missing her, she stepped out in front of him going way below the speed limit, so close that even with the best brakes in the world he'd have hit her. So he tried to swerve - she'll always go one way or the other when she sees him so its a fifty-fifty chance. And yeah, that might be true. But its not that simple.
If she's visible on the pavement he should, perhaps, see her. And in a complex city environment with multiple hazards to track on and off the pavement its fair to argue that no one should be going at a pace beyond which they can't track all of those hazards. Which, of course, means that people should be cycling and driving much more slowly than that. But we never see prosecutions for motorists hinging on 18mph in an urban area being too fast, so I don't think that can be used here. Was she, therefore, visible and about to step off the pavement? On Old Street? Probably not.
I can't sit and claim its impossible he could have ridden differently to avoid the crash. I can say with certainty no one riding or driving at that speed, in that environment, would be considered in violation of the law. So in that context, its very hard to see how he could have avoided the collision.
We can say with certainty that better brakes wouldn't have helped a great deal, if at all. He's got 1m to brake after 5m thinking time - he can only go on instinct so he's got to try to swerve. If he's got a front brake and brakes hard at that speed AND swerves he'll go straight over the top and probably hit her anyway.
So, tragically, we can't claim that he could have avoided this collision. His brakes (or lack of a front brake) are not the issue - and I suspect thats why he was not found guilty of manslaughter.
But I should add that I don't get how his version of events is meant to have happened. Apparently he shouted a warning. In 6m? In under a second? Or in 1m, in around an eighth of a second? Well you might get a grunt out. Yes, people are entitled to remember things differently (and thats just how things are, we know this happens) and they will put their own slant on what happened. But if she stepped out, without notice, 6m in front of him (and that seems to be accepted) then the chain of events we're told about seems implausible. And I'd call his account, where he claims to have shouted to warn her twice, completely implausible.
Has Justice Been Served?
He was quite unrepentant, and that won't have helped. Comes across as a nob if I'm honest, but that's no crime. Our prisons would be awfully full if it were. Should that lack of repentance impact on the sentence? Yes, I think that's probably fair. Is the prosecution just in context of whether he could have done anything to avert the collision? No, I don't believe it is. If you kill someone with your car which later proves to have an unrelated fault, you're not prosecuted for that death on the basis of said fault. If you run someone over but it turns out your brake light wasn't working, you may be prosecuted for killing someone but the brake light won't be an issue in that prosecution. So in context of what happened, and whether he could have avoided it? I don't see it. I don't get how this is just.
Is the Sentence Proportionate?
Yes, and no. A death on the road is a serious matter and if someone is found guilty of killing another person I'm of the view that the sentence should reflect the magnitude of what has happened. 18 months sounds light in comparison.
This guy killed two pensioners with his lorry. He was going above the speed limit and had at time in which to see the pensioners and react, but didn't. He wasn't concentrating and as a result smashed the skulls of two blameless old people, and they died. OK, he wasn't allowed to drive home, but he wasn't jailed. The family of the two pensioners said that he basically got away with it.
I am uncomfortable with this prosecution considering the simple physics of the case. I'm uncomfortable with the sentence given out - not within the context of how serious road deaths are, but in the context of how lax punishments for other killers often are. Yes, to me, this Alliston chap seems like a smeg head - his reaction to the accident was awful. But if he'd done the same thing in a car? Its doubtful he'd even have been prosecuted and, if he had been, found guilty.
We need consistency in law - and this verdict is not consistent with other similar cases, where the prime difference is the vehicle used. It does look like his treatment was more harsh because he's killed with a bicycle. I find this worrying - and I fear the backlash being aimed at all of us now.
I'm not able to say that the courts decision is wrong, of course, I wasn't there. But I find the lack of explanation of the chain of events, the fact that we must believe an implausible sequence of events to have faith in this verdict, deeply troubling.
*Alliston changed his mind about this - some accounts say the phone was found next to her. Its hard to know whether this is true. But in itself this doesn't change the physics. Regardless of whether she's on her phone, he's got the same distance and time to stop.