BUSTED: This one goes squarely into the "myth" category because of how much "slippery surfaces" is overused as an excuse to avoid the minimal effort that would otherwise be required to create the right conditions for cycling.
Right now, hundreds of thousands children, youth and adults ride year round in winter conditions without fear. Part of our role is to show cities that "slippery conditions" should not be used as a reason to neglect investments in cycling and maintenance.
Yes, the "typical" winter city is one that experiences periods below 0 degrees, and, yes, water does, indeed, freeze. Yes, we know ice is, well, slippery. However, with good maintenance techniques in place, snow and ice can be maintained very rapidly to a surprisingly hard, textured, grippy surface — more than adequate for any bicycle. The choice to ride that bicycle also happens to be much safer than the main transport alternatives available to cover that same distance.
What we find perplexing — and why this is most definitely classified as a myth — is the double-standard that is applied to bicycles vs. driving heavy, fast moving cars. A 2 500 kg car or a big surly semi-trailer can/will/does also slip on ice, as we all know, and the results at these high speeds are far more catastrophic both for the driver and everyone else in your community. A city full of cars and with no bicycles is a city guaranteed to have high rates of death and serious injury by nature of the vehicles being used. Whereas a city where everyone cycles in winter (i.e. cycling in the absence of cars) would almost certainly mean that almost no serious traffic injuries or deaths would occur in traffic. All of this tells us that slippery is not just an overblown concern, it is also an ethical red herring being applied to an issue that must always be considered in context. If you decide not to ride a bicycle because a car is safer when it is slippery, think again.
As for skill, well, we suggest trying to ride a bicycle and deciding for yourself. You might be surprised at how easy it is.