Conservation areas surrounding lakes and rivers are popular targets for riding. One scenic trail nearby runs within inches of a 20 foot dropoff to a small river below. Should you fall, choose to go swimming, or even have to rescue a buddy who rode over the edge and cratered into a river, there are some important things to keep in mind.
A good strategy to avoid falling in the first place is to look away from the edge of the trail. Just as it is best to look away from the tree, or look towards the place you're trying to steer, don't look down, or that's where you'll end up.
About Swimming in General
Learn to swim. This is the most important element of staying safe in and around the water. Swimming courses are offered nearly everywhere, and it's a fun and rewarding compliment to cycling workouts.
Beware of the "dangerous too's." Too tired, too cold, too far from safety, too much strenuous activity.
Steer clear of drainage ditches and arroyos for water run-off. Aside concrete being a harder surface to crater on than dirt, they can change from a trickle to an overwhelming flood very quickly after heavy rain. No swimmer is a match for the sheer power of the water flowing through such a channel. Fast water and debris can readily kill a rider who ventures too close.
It it easy to choke and drown if chewing gum or eating while swimming. If you fall in while eating, chewing gum, or drinking from your water bottle, discard the bottle or food as you fall. Don't swallow what is in your mouth -- spit it out! Otherwise, the wasted time may cause you to miss your chance to get in a deep breath before you wind up under water.
It is not necessary to wait for an hour after eating before swimming, but use common sense. It is wise to leave some time to allow digestion of any large meals to begin before swimming -- or riding, for that matter.
Alcohol mixes with swimming even more poorly than it does with cycling. Judgment, balance, an coordination are all compromised by alcohol, as are swimming and diving skills. The ability to keep warm is also reduced when under the influence of alcohol.
Under all circumstances, enter the water feet first in a fall. You otherwise risk serious injury (including to the head and spine) and drowning should the water be anything but clear and deep.
Keep away from your bike, as it will slow down very quickly when it meets the water, creating the distinct possibility of a crashing into a slow-moving bike after a twenty foot drop. (Ouch.) It will take a while for a mountain bike to flood and sink, so you do not have to hold on to it.
If jumping in, rather than falling in, always take a second to look and pick a touchdown spot that is clear and deep.
Getting Out of a River
If caught in a current, do not try to swim against it. Gradually swim out of a current by swimming across it.
Never swim under an obstruction in the water, such as a fallen tree. Stay above water at all times, and avoid situations where you could get caught or tangled up and drown. Don't swim under boats, rafts, or docks either, for that matter.
Be conscious of potential hazards such as murky water, hidden underwater objects, unexpected drop-offs, and aquatic plant life. Float with your feet downstream, and keep your feet away from rocks where they could become caught.
While nobody is going to abandon their $2,000 pride and joy because they ride into a knee-deep creek, if you are unable to stay above water and hold on to the bike at the same time, simply accept that. Anchor your bike from the current against a big rock or fallen tree if you can, but do ditch it if you must. You'll be able to recover your bike from the bottom or from downstream with the assistance of rope, lifejackets and helpful park rangers. Remember, fresh water isn't much more harmful than rain; the bike won't corrode if left while seeking help.