In a well-intentioned bid to encourage Winter cycling, a recent article in the Toronto Star was ostensibly titled “EVERYTHING You Need to Know About Winter Cycling in the GTA” yet it only presented a rather simplistic collection of generalities about cold weather riding, while offering precious little insight to prepare rookie riders for the actual realities of rolling on winter roads. A forgivable piece of general interest filler, if not for one glaring example of genuinely bad advise on tire pressure:
” Drop tire pressure by 10 to 20 PSI (pounds per square inch). It does slow you down,” Mohamed says. “But it gives you way better traction.”
Since this advice is by no means applicable across the board, and can actually create problems in many circumstances unless more context is provided, it behooves us to look at this and a few other issues a little more closely,to see what else the “Experts” might have missed!
Let’s start by finishing off the subject of winter tires below…
Where the Rubber Meets the Road
First of all we need to consider just how many bikes out there are big “Cruisers” or “mountain bikes” (MTB’s) with much larger tire sizes. A 20PSI drop in pressure on an MTB would likely account for about 50% of your total tire pressure – even if your tires were reasonably well inflated to begin with. Dropping even 10PSI’s out of an already soft tire could be downright dangerous on a busy city street, and this should have been clearly stated in an article written for such a general audience.
We can only presume that this poorly qualified recommendation should only have been applied to roadbike tires…But even then, this would represent a slightly risky proposition without first advising that reader/rider to check the specifications of their tires to begin with, and also being extremely clear on the risks raised by drastically lowering tire pressures under critical winter conditions.
Pressure is also a Function of Temperature
20PSI is usually the minimum to begin with for most MTB tires, but this minimum is NOT recommended by any experienced riders and competent Mechs who can give you many reasons to not flirt with bare minimums in cold weather. If you doubt this logic, then just ask yourself if driving a car with the bare minimum of oil in harsh conditions would also be a good idea!
Here are a few other risks:
- Pinch flats
- Rim damage
- Tire shifting it’s proper rim position
- Loss of energy transfer efficiency
- Dangerous risk of weak sidewall pressure leading to loss of steering control, or even roll-over in a suddenly tight turn
So even if you didn’t unwittingly drop your MTB tires below the bareminimum recommended pressure by taking this poor advise in The Star, the greater added risk of this “winter tip” comes from the fact that any weather related drops in ambient temperature will also radically drop an already low tire pressure well below the danger point. You might remember your high-school physics relating air temperature and pressure?
Essentially, this is an effective danger that you likely wouldn’t even notice until you tried to turn suddenly on a dangerously under-inflated tire. This would likely happen as the result of an unpredictable event that arises when you desperately need your tires to perform their best in order to avoid peril, on already bad surfaces. Anybody who says that you should simply avoid turning too hard during any winter driving is clearly too foolish to take seriously to begin with, but we’ll reserve a discussion of balancing techniques on slippery roads for a later installment.
One well-meaning soul suggested via Twitter that so long as you stay within the recommended minimum tire pressure, and avoid taking turns to fast, then “your bike will be fine”. Well, first of all you should keep in mind that those ‘minimum pressures’ are based on a reasonable atmospheric pressure and temperature as well, and will not be anywhere near adequate at -10 weather. Since we are talkign about Winter riding, and if you need to take a sudden turn to avoid danger with a tire at bare minimal pressure, you might soon discover just how frightening it is to have soft tire walls roll out underneath you as you suddenly find that your wheel is neither supporting your turn properly, nor helping you keep balance, and both you and your bike get tossed in the exact direction that you’re likely trying to suddenly avoid (life is unpredictable, and road traffic is even worse), all on what we can presume is an already rather difficult road surface to steer on to begin with. Get the picture Bikeroo?
In short, flirting with a minimal tire pressure just for the sake of some added comfort, or or the slightly improved traction you’ll get over uneven surfaces is already an added measure of risk in dry weather. So long as your tires aren’t OVER-inflated, tire pressures should never be trifled with in bad winter conditions, despite what any supposed experts might tell you via their third hand sources.
When it comes to Winter riding your best indicators are your gut, the feel of the road through your feet and your derrière, and your own well-balanced brains. Trust yourself and your developed instincts first, and you might even learn to enjoy the unique challenges of winter riding. It’s a long season, and there’s surely lots more of these challenges to come.