Friday 13 June 2014

Rate Limiting Steps. Or, don't overtake and brake, you idiot.

I remember learning a really important lesson in kinetics in chemistry at school. Well, from my chemistry teacher rather than in class. 

It actually came in the corridor on the way up to the school dinner hall, where we'd always run up as a bunch of lads to join the queue, before hanging around waiting to be served and for a table to all sit at and eat. He questioned why we ran, explaining that its like in chemistry where you've got one step that governs the rate of whats happening. You can run up the corridor all you like, it won't get you sat down and eating any sooner. Rate limiting step. 

Now thats a good lesson in life, and its a good lesson in chemistry - there's no point fannying about with the steps of a reaction that don't govern the rate or efficiency of a process, its the rate limiting step that governs how quickly something will be produced. Of course later in education I encountered all sorts of reactions where, for example, because reagents are really cheap, or because you can recycle a reaction volume to re-use any excess you end up with some parts of a process being given way more feedstock or energy than they really require - or, in other words, despite the rate limiting step thing holding true, you still have 'too much' in the other steps because there's no good reason not to.

Yesterday I was riding along, catching up with a slower cyclist, when a car passed me and pulled in. The driver obviously had to then slow down for oncoming traffic, only to be stuck behind the cyclist in front as we approached the red light at the end of Carlton Way. She seemed most put out (to the extent of sounding her horn and yelling) when I passed her to get in to the cyclists box in front of the traffic. Of course, you always catch them. You always go past. Their average speed in traffic is way slower than ours - overtaking us never gets them anywhere.

The parallel between this and the lessons one would have hoped to learn at school are pretty obvious - gunning your engine and overtaking only to be stuck a little further on while a cyclist overtakes you again is just stupid, didn't you even go to school? But when we think further, what the car does is make speed effectively free. Might be a few pennies to overtake and slam on the anchors, but its no physical work and any financial cost is lost in the general money pit of motoring. Inefficient, downright daft decisions have no consequences.

Cars used on urban and suburban roads are capable of reaching absurd speeds, in moments, with no effort on the part of the motorist. In fact to avoid doing so is considered so strange that if you're driving behind a cyclist the next driver will very often be right up your exhaust telling you to get a shuffle on, mate, ain't you got nowhere to go? Its only a fucking cyclist. And it you hit the cyclist? The courts will understand.

We have made aggressive, pointless and downright dangerous overtaking morally, financially and legally free. As a result of this bad overtaking is the norm rather than the exception - to the point where we then tell cyclists to ride assertively in the middle of the lane and act all surprised when motorists bully us out of the way. 

Until we take this kind of dangerous, antisocial driving seriously in the UK we'll never really tame aggressive motorists. But how do we take motorists back to school and get them to realise the importance of rate limiting steps?


  1. Easy: make them ride bicycles as part of the driving test.

    Motorcyclists have to do "Compulsory Basic Training" before they're allowed on the roads. Motorists should have the same, and have to pass a cycling proficiency test to prove they understand traffic interactions.

  2. Nah, motorists do it Copenhagen and other cities where everyone bikes, too. In fact, with enough bike traffic, bike riders do it. There's a lot of variance in bike riding speed, and some riders find it very hard to adapt when bike lanes are congested.

    I think it's simply that speed is intoxicating, and we live in a culture with next to no patience.

  3. We would like to invite you to a unique experience where cycling and interactive gaming collide on the streets of the Cambridge

    Digital pioneers Blast Theory bring their critically acclaimed cycle piece Rider Spoke to the city for the first time from 03 – 06 July as part of VĂ©lo Festival, celebrating the Tour De France passing through the city.

    Equipped with a bike and a handheld computer mounted on the handlebars, you will ride out into the streets of Cambridge. Aided by your computer and the woman in your earpiece, you will find a hiding place - and get asked a question. For a minute or two – alone, in an out of the way spot – you reflect on your life and record your answer. Cycle on and find the hiding places of others. Listen to their answers in the places that mean most to them.

    Navigate the streets of the city as you never have before in this interactive part game, part performance for one person at a time!
    Rider Spoke premiered with a sold out season at the Barbican, London and has since been shown worldwide.

    For more information visit:

    As a local blogger enthusiastic about cycling we would like to invite you to take part in a preview on Wednesday 2nd July from 4pm.

    To confirm and book your slot please email

    1. Oh, I read about this, and it sounds great fun. Regrettably all tied up next week - can't make that. But good luck with it!