One of the things I love about working on bicycles, both my own and others', is setting the bike up so it best suits the rider and the use they intend for the bike. I think most folks assume that the way the bike comes from the factory or the bike shop is the way it's meant to be, and never think of changing it. On the contrary, any bike can be modified, and in many cases should be, in order to really become "yours".
First off, what do I mean by "yours"? Well, a bike you own should first of all fit your body. Bikes are typically designed for the "average" person, in most cases, the average man. Since few of us are in fact, average, and 51% aren't men, the first thing I recommend to folks is that we figure out how to make their bike fit them better. This may simply involve adjusting the height and angle of the saddle and handlebars, as well as the fore and aft position of the saddle, or it may involve changing the saddle, bars, or stem (the part the bars attach to). In some cases, all of the above!
I'd have to say, the most common fit complaint I have from customers boils down to the handlebars being either too low or too far from the saddle. This sometimes manifests itself as a slight discomfort, but in more severe cases can cause acute pain or numbness in the hands, wrists, arms, neck or shoulders. Most people don't spend a lot of time supporting a lot of weight on their arms, so low and far handlebars can be quite uncomfortable. Granted, there is some degree of "getting accustomed" involved, and the more you ride, the more comfortable lower bars can feel. But for most people, the answer is to raise them or get them closer or both. This can be accomplished with a different stem, perhaps, or even different handlebars. Visit your local shop and talk about the possibilities.
The next most common comfort issue (and it's nearly a tie here) is the saddle. I'll start right off saying I can't tell you for certain what saddle is going to be best for you. That's a very personal part of one's anatomy, and we're all different, so what works for me may not work for you. In fact, many people, in looking at my bikes with their Brooks tensioned leather saddles, think I must be some sort of masochist. Far from it... I have found over the years that for my behind, and my style of riding, nothing is more comfortable than the Brooks B.17 saddle. But that's me. You are different. The best advice I can give you is to talk to your local shop and get their feedback. One thing to think about is the shape and softness of your current saddle, and how it feels beneath you. Does it feel so narrow that it threatens to split you in two? Or is it so wide your thighs rub excessively? See why saddles are hard for folks to talk about? :-) Seriously though, think about the sensations you feel on your current saddle and then compare the shape and softness to other saddles to find what works for you. It may take several attempts... but don't give up until you have something that works for you.
Now beyond basic positioning issues, you can customize your bike for your needs in other ways. You may not realize it, but your bike's gearing is not set in stone. Do you feel you struggle to grind up steep hills, feeling like you're pedaling in concrete? Or does it feel like you end up with your feet flailing at a crazy high speed and your highest gear is too easy for you? Either extreme is pretty simple to adjust, although depending on the components on your bike, it can get expensive. But if you aren't enjoying the ride, you won't ride the bike, and what's the good in that? Again, talk to the folks at your local shop and see what they can do for you.
Another change to consider is your tires. Many bikes come from the factory with pretty generic, utiliatarian tires that provide a decent ride at a modest price to the manufacturer. Given the enormous selection of brands, models, sizes and styles of tires available today, there's a good chance that there's something better for the type of riding you do. Do you ride mostly on smooth, good roads and bike paths? Go for a lighter, faster-rolling tire. Commute on rough, glass strewn city streets, and can't afford to be late for work due to a flat? Go for the rugged, wide, kevlar belted models. Ocassional jaunts off road, in dirt? There are tires for that too. Try to find someone who does the kind of riding you do, and ask their advice. Experienced riders will have pretty strong opinions, and as long as their priorities match yours, you should get good advice.
Now, beyond all of these central matters, there are other ways to truly make your bike suit you and your riding. If you're like me, and don't want weather to keep you off the bike, you should give serious thought to fenders... they will greatly increase your comfort and cleanliness (and your bike's) in the rain. Any chance you'll be caught out after dark? Then invest in at least a basic front and rear light. I'm a big fan of the small, self contained headlights from Planet Bike, and blinky red tail lights from PB or Cateye, but there are plenty of other options. For bikes used on a more regular basis for transportation, I really like the dynamo hub systems from Shimano or Schmidt, which free you of worries about batteries. Don't forget a bell, if you regularly ride multi use trails... walkers, joggers, rollerbladers and the like seem to respond well to a "ding ding" rather than a shout.
Then there are the items that just make a statement, or simply personalize your bike so it "looks right" to you. Perhaps it's a matter of getting just the right color of bar tape on a road bike (I have been known to agonize excessively over this!), or an assortment of stickers that express your world view ("If you were riding you'd be happy now" is a personal favorite of mine). Or maybe it's something whimsical... for example, my "fixed gear" bike (a type of bike known to have some very "serious" fans) has a colorful, parrot shaped squeeze horn! These are the things that often come over time, as you and your bike become acquainted, and you slowly shape it and make it yours.
So don't be afraid to change the way the factory built it! There's nothing sacred, and as long as you know a bit of what you're doing, or know someone (like your local shop mechanic) who does, you can't do much harm. Start with the fit issues and go from there, and soon you'll have a bike that's like no other, and suits you to a "T".
(Look for a future post with specific examples... but for now, take a look at the two photos here. Both are of my '85 Miyata 210 that I built up for commuting and shopping... the first photo is how I initially set it up, the second is how she is now... see if you can spot the changes!)