We'll create our own mud boots with duct tape.
We'll create our own mud boots with duct tape.
Mud-Proofing the Cables

First! DO NOT RIDE ON MUDDY TRAILS! But if you're heading out onto ATV tracks or a deliberately-muddy cyclocross track, we have some advice for you. Here's a quick way to keep the cable damage to a minimum.

For each place where a cable enters a housing, tear off a 4-inch strip and a 1-inch strip of duct tape.
Place the smaller strip, sideways and face down, in the middle of the sticky side of the larger strip. (This creates an area with no adhesive where the "mud-proofing cover" covers the entry of the cable into the housing.)
You don't want adhesive to get on the cable where it moves into the housing!
You don't want adhesive to get on the cable where it moves into the housing!
The non-sticky part goes over the part of the cable that enters the housing.
The non-sticky part goes over the part of the cable that enters the housing.
Fold the tape over the frame where housing meets raw cable. Stick it down, about 1/2 inch behind the end of the housing.
Wrap the tape around the frame, occluding any open spaces. Pinch the sticky part of the tape around the cable -- the back-side of the smaller piece of tape keeps adhesive from getting on the part of the cable that enters the housing.

After the mud and water exposure, remove the tape. Use adhesive remover (or nail polish remover) to get any stick-um off the cable and frame.

The mud-proofing is good for only one ride.
The mud-proofing is good for only one ride.
Some cable spots are more prone to get water inside the housing.
Some cable spots are more prone to get water inside the housing.
Here's a cable-killer! This bottom-pull front derailleur cable goes directly into cable housing through this hole in the frame. Mud and water will run into the housing every time you shift. The problem here is, the cable housing opening faces up, where mud will splatter then be pulled by gravity into housing where the cable enters.

Let's cover it up.

Once you're through with that cold, muddy ride, pinch the duct tape down to make sure it's securely in place. Then wash the bike down fully. After hosing, peel the duct tape away.

If you get adhesive buildup on the cable, clean it off with acetone or nail polish remover. Paint thinner can work, but not as well.

Other winter-proofing items, with my humble experience:
Detachable rear "mud fender": Worthwhile. The most convenient are those that clamp quickly to the seatpost. Keeps the water from spraying up your butt and back.
Detachable front "mud fender":  No. Somewhere, there must be one that will work. I tried three brands. But none survived more than a single ride. First fall = break fender. In fact, I broke one in my garage when my thigh bumped the front wheel as I walked past.
Derailleur protector:  No. Must be a roadie thing. Forget it. A pain to put on. And, it will quickly fill up with mud. Worse than worthless if you ride in real mud.
Shock covers:  Not impressed. The muddy water quickly gets inside, where the sand and grit is caught by the sleeve and held against your stanchion. Even if you remove it and clean it after every ride, your shock will wear out faster with a cover than if you do nothing.
Shoe covers:  Sure. Why not?