The following apology was printed in the Guardian's Corrections and clarifications column, Thursday February 22 2007
Safecote Ltd. In the report below, we were wrong to imply that the writer's slips on his bike were caused because the road had been treated with an anti-icing product manufactured by Safecote Ltd. In fact, the road on which the slips occurred had not been treated with Safecote. As the article stated, the product has been tested by the Transport Research Laboratory, which found no adverse effects. These tests have been supported by further research carried out last year with Durham University. Apologies.
One Saturday recently, I was taking advantage of a forecast for one of those rare cold but bright days. There had been rain in the week, and then a frost, so the gritting lorries had been out the night before. A chill north-westerly was blowing, but by the time I was on the road, I knew the temperature was well above freezing; I wasn't worrying about ice.
It took me all the more by surprise, then, when I locked up my back wheel under moderate braking coming into a roundabout. Nothing dramatic: the back end just stepped out for an instant, but it gave me pause for thought. Then, a few miles down the road, the same thing. This was weird.
The roads were three-quarters dry, so that you could see the white streaks of salt. Yet, where the road was still dark with moisture (and the salt makes it take longer to dry), the surface seemed as greasy as a chip-pan. It didn't make any sense, but I took it extra easy: a rear-wheel slide you can catch, but if your front wheel goes out from under you, there's no way back - you're headed chin first for a closer acquaintance with the work of John Loudon McAdam's disciples.
There are few feelings so unsettling as riding on a surface that, you realise, has withdrawn its usual quota of adhesiveness. An almost existential doubt comes over you. Instead of having trouble imagining why you would ever fall off, it becomes difficult to figure out how you can stay upright a moment longer. Corners you would normally auto-pilot your way round become treacherous, off-camber pistes. The cyclist who has apprehended that she or he is riding on a surface that cannot be trusted has entered a disturbed ontological state for which, as so often, German has the best word: Unheimlichkeit - uncanniness, or eeriness.
I completed the rest of my ride cautiously, but without incident. The experience had slightly blighted a beautiful morning, but I'd been lucky enough not to have been caught out. I wondered vaguely if my tyres were not as good as they should be, but that wasn't it - they were the same brand as I race on.
I didn't have an answer ... until, some days later, I came across a thread on one of the myriad internet cycling forums that now serve our various communities of interest. Several posters mentioned mysterious falls on strangely slippery roads; one mentioned a product called "Safecote". I did some homework.
Safecote is an additive that a growing number of local authorities are combining with the salt they grit the roads with. It is more expensive than plain salt, but it has a number of useful properties, including a claimed cost reduction since it aids better distribution and so results in lower use - with benefits also to the environment and the councils' own hardware (as the mixture is less corrosive than pure salt). It is described as a "by-product of sugar production" - in plain English: molasses.
The manufacturer cites research by the Transport Research Laboratory, which tested for grip and found no adverse effect compared with existing gritting compounds. So, any contradictory evidence is anecdotal, not scientific - but search the motoring forums, especially of motorcyclists, and you will find plenty of drivers who are convinced that the addition of this viscous, brown, organic liquid, with salt, to a damp and dirty road surface is making roads slimy - even as it stops ice forming.
My favourite Safecote-related anecdote, though, concerns a different sort of hazard. In Flintshire, north Wales, the sheep have discovered it's a bit of a treat. They've been flocking to rural roads after gritting to lick the salty-sweet stuff off the tarmac. Four legs good, it seems; two wheels bad. Mind how you go.
I recently went to San Francisco and rode my friend's fixie (luckily, with a front brake). Now I'm hooked and looking to get myself kitted out, but have no idea where to start.
Luke Mourino, via email
Riding a "fixie" - fixed-wheel bike - on the hills of San Francisco is impressive, though I'd want a rear as well as front brake. You have two choices: single-speed (which has a free-wheel mechanism, allowing the rear wheel to rotate independently of the cranks) or fully fixed (you have to keep pedalling as long as the bike is in motion). The latter is truly addictive.
Specialized's Langster is amazing value at less than £400, but many other niche manufacturers do their own versions. I ride an adapted old steel frame myself.
The fount of all fixie wisdom on the web is Sheldon Brown (www.sheldonbrown.com).
· Please send your cycling queries to email@example.com