Well, water and a whole additional set of hazards to watch for. I know that many riders will not ride in the rain. I know that my wife questions my sanity when I start putting on the gear to ride to work when it is pouring down rain outside, but the thing is, I choose to ride as my transportation. It is unreasonable to say I am not going somewhere just because it is raining. So I ride in the rain.
Yesterday was an excellent example. I knew the forecast was for thunderstorms all day. All this meant was that I dressed accordingly, slipped on the rain gear and out I went.
Sure, once on the bike, things are a little different. Speeds are a little lower. Turns are taken with more emphasis in maximizing traction. Really, just a normal ride with some extra awareness, except for one thing. Other drivers behaviors become even more erratic. This is expected, and is just something to be dealt with. I find it very interesting that other riders in the area intimidated by riding in the rain.
I think what bugs me the most about these riders is that many of these same riders think nothing of heading to the mountains and doing double the posted limits in the twisties but are uncomfortable with a little rain. It would seem to me that learning to cope with less than ideal conditions would serve to make a better rider than being a hooligan in the mountains in perfect conditions.
Either way, I find a certain perverse pleasure in the less than ideal conditions. A thumbing of the nose that says to nature, I relish what you have to share. In many ways, it falls into the same category as the cold and the very hot. You take it for what it is and enjoy it for the same. All the while, taking care to avoid the complacency that can turn deadly.