But before we go too far, just a reminder that Cycling Centre workouts don't get cancelled due to rain. For starters, I think it's important to practice riding in all conditions, especially if you plan to race or participate in events. But even if you don't, you never know when you might get stuck riding in the rain, and like all things, the more you practice, the better and more confident you'll be.
So lets start from the bottom up.
Road Surface: The first minutes when the rain starts to fall is when it is most slick. Oil and dust mix with moisture making it more slippery. Once this first layer washes away then it is not as slippery. Paint and metal (man hole covers, bridges) are also like ice in the rain and should be avoided. Be extremely cautious on freshly paved roads as well, they really are like riding on ice.
Tire Pressure: If the forecast is calling for rain then ride at a lower tire pressure, above the minimum listed on your tire, but close to it. For most road tires this will be around 80 psi and will provide more surface area and grip which is helpful on wet roads. To learn more about tire pressure and what psi you should pump your tires to check out this link.
Clothing: Rain jackets are helpful in staying dry, but don't breathe, trapping in the moisture we create from working hard. When the temperatures are warmer you might be more comfortable, temperature wise, without a rain jacket. If it is spitting or drizzling, a wind jacket is often enough to protect you against the moisture. Glasses will help protect your eyes against road debris that flies up in the rain, but also limits visibility by dirtying the lenses. As the skies darken it also becomes harder to see with glasses. Putting in clear or lighter lenses (yellow) is a good idea, or sometimes taking your glasses off and putting them in a safe place is best.
Visibility: If you are having difficulty seeing, then drivers are too. Bright coloured clothing and lights help make your presence known. Also ride more in the lane of traffic as puddles form near the curbs, storm drains get backed up, and drivers are not expecting cyclists on the road. If you can, avoid puddles as you don't know if there are pot holes, branches, or other obstacles hiding underneath waiting to do damage. If you are riding with others, then stagger if you can so the wash from the wheel in front doesn't hit you in face decreasing your visibility and bringing up dirt and stones that might hurt on impact.
If it is raining so hard that you can't see across the street then it is best to pull over, seek shelter, and wait for the storm to ease up. This also gives you a chance to better know your training mates and make new friends.
Braking: Wheel braking surfaces will be affected by road grime as it collects on the rim. This results in weaker braking ability, grinding noises, and "stickiness". Create more distance between you and others, feather the brakes, break sooner. If you have a carbon braking surface then it will take you much longer to come to a stop then when they are dry, be prepared. Do some practice braking when it starts to get wet so you get a sense of how different your bike slows. Here is a video with some good visuals.
Turning: Your bike likes to go straight, in wet and dry. So as long as your wheels stay in alignment then you will most likely stay upright. Most falls happen in turns or due to braking. When turning in wet, make sure you brake before the turn, when you start to turn you should be able to release the brakes, so enter the corner at a speed slower then you normally would, release the brakes, look where you want to go, and lean instead of turn. What I mean by that is keep your wheels in alignment, weight on your outside foot and lean on the inside hand instead of turning your front wheel. Turning a wheel, braking, and too much speed lead to falls. If the turn is tight and you have to turn the front wheel, then do so at a slow and calculated speed.
Post Ride: After every wet and dirty ride it is important to wash your bike. Dirt and grime get in to all kind of places where they can do damage when it is wet, which causes friction, awful sounds, and damage. To make it simple, riding a dirty bike costs you money in maintenance and parts, and it makes you go slower. If you do't have time for a full wash, at least hose down your bike and wipe off the chain and moving parts after the ride, and re-lube, do a 5 minute bike clean. Then schedule in to your calendar time to correctly wash your bike. Here is a video to show you how.
Chances are your shoes got soaked too. Stuff newspaper tightly in to your shoes. Then before you go to bed replace the paper with dry paper sheets and place on a heating vent. Your shoes should be dry in the morning. If your shoes get stinky you can wash them in the washing machine with towels (to protect the washer), but let them air dry or do the paper trick. Putting them in the dryer can lead to shrinkage.
Practice riding in the rain, take it slow, stay visible, stay upright and safe. We didn't talk about the benefits of riding in the rain, but one is the opportunity to find a pot of gold.
Keep the rubber side down.