VED isn't a road tax. No, really, it isn't. I'm not even getting in to that here.
But lets suppose for a moment (as I did on twitter yesterday, conveniently storified by a very nice person) we're in a parallel dimension where VED really does pay for the roads. And that its considered fair and reasonable that people pay proportionally for the wear and tear their vehicles inflict thereon.
How much should cyclists pay?
We can do a few back of an envelope calculations to get how much we'd be expected to pay into context.
Lets begin by looking at the relative damage we do - usually this is worked out by a fairly simple formula - for each doubling of mass you multiply the harm done by 16.
If a cyclist weighs on average 75kg (thats inbetween average woman and average man), we can get to a round-ish number by saying the average bicycle could be about 15kg. So we're putting 90kg worth of damage down on the roads. Thats very likely so low that other than the physical surface atoms of the paving, we're not going to be reaching the kind of load that reaches an activation energy to cause any damage at all, but we'll stick with it for now.
Depending where you are in the world cars tend to be different masses, but a workable average is about 1500kg. Multiplying up, 90kg x2 is 180kg, then 360kg, 720kg, 1440kg... We've got to double the mass 4x to get an equivalence.
Someone recently told me he'd paid £200 VED, so lets say thats average. Sounds about average. If the average car costs you that much, we divide by 16, 4 times, to get to £0.003.
But lets flip it around. Often we hear people saying they'd like cyclists to pay SOMETHING towards the roads. So shall we say a tenner? Proportionally you'd pay £655,360 for a car.
I found a stat at the RAC saying there are 34.5 million motorised vehicles on the roads, and from the utterly reliable source of twitter I've seen a figure of about £10 billion per years on road maintenance in the UK. Do the maths and thats about £290 per person.
Back calculate from that and, based on road damage alone (ignoring the fact that cyclists are probably not damaging at all), and the 3 million (according to CTC) regular cyclists in the UK would pay 0.4p per person, per year. Or all together we'd be paying £12,000.
There are two simple conclusions to draw here. Firstly its absurd to suggest that cyclists should pay 'road tax'. It transpires that its even more aburd if you do the maths. And, secondly, just dealing with road wear and tear alone, VED ain't high enough. Want cyclists to pay 'road tax'? Then start paying a fair share for your car!