I'm wondering if all the moisture from being out overnight will damage my bicycle. I'm thinking 30+ days of being in use, with maybe a couple of those days being light rain. If the water will damage my bicycle, are there lightweight and compact covers that could be suggested? Or, would just wiping down the bike with a towel in the morning work to prevent damage?
- As Daniel indicates - overnight moisture on a well maintained bike isn't a concern. A little rain won't hurt. Others may disagree but I wouldn't get a cover.
- But, depending on how much rain there is and how long it lasts, when riding in the rain often the rain mixes with dirt/dust/sand and creates an abrasive liquid that can be hard on the drive train - and can even work it's way into bearings and cables.
- Fenders help keep the water mixed with dirt that's on the road off of you and the bike.
- I think of rain / water as a riding factor that increases how often I should do maintenance. 30+ days on the road should include at least drive train cleaning and lubrication.
- Here is a link to an article on bike prep for rain. The article links to washing and lubrication articles.
The bike will be fine as is. I have personally never bothered to cover, or do much maintenance to touring bikes (beyond wiping and lubing the chain occasionally). If a bike was so delicate that a couple days of rain would render it useless, then it really shouldn't be used for touring.
Typically a couple days wet won't hurt most well maintained bikes. About the only real concern would be if your chain was not receiving any maintenance during your tour, then, depending on the quality of the chain, some surface rust could form. Even then, this would be largely cosmetic and of little concern functionally (i.e., next day's riding would break free any small amount of rust forming in moving joints).
If you are in wet conditions for extended periods (i.e., weeks to months), then some surface rust can be expected (depending on quality and materials used on your bike). But again, even here, it will be largely a cosmetic concern.
The only really concern for rust is in long-term storage or neglect. Here extensive surface rust can eventually start bind moving parts together. This however takes a long period of neglect (e.g., years). If you use your bike frequently, this is highly unlikely.
I agree with the others saying that overnight moisture is not a problem.
However, you may wish to cover your handlebars and saddle (seat). I like to use foam-pad grips on my touring-bike's handlebars, and these can absorb water, which is then transferred to your gloves/hands when you start out for the day. It's only a minor annoyance for-sure, but an annoyance none-the-less.
I wouldn't consider carrying anything with significant weight just for this purpose though.
I always carry a couple of lightweight "bin-liner" bags when I travel (by bicycle or not) in case I need to pack, say wet clothes or muddy boots, etc. This is enough to cover your handlebars and one for the saddle - of just use a plastic bags you pickup on the way. (Oooh, maybe a shower-cap (for your head) would work on the bike seat).
My seat is a plain-leather seat (Brooks), I don't let it get wet if I can help it.