Unfortunately, bikes are expensive.  And, with the plethora of bikes to choose from, it’s easy to buy a bike that’s not quite right for you.

In general, I recommend that you do your first triathlon on the bike you already have–whether it’s a mountain bike, hybrid, whatever–just to see if you really like doing triathlons.  If it turns out you don’t enjoy triathlons, then you haven’t wasted your money!

However, if you do decide that you want to participate in triathlons long-term, it’s definitely worthwhile to purchase a triathlon bike.  They’re faster and more comfortable than a mountain or hybrid bike, and even an entry-level bike will last you a lifetime if you maintain it properly.

Here are my Top 10 recommendations for triathlon bikes in the 2010 season.

10. Specialized Transition Comp. Price: $2800.  This carbon-framed bike makes the list because of it’s adjustability (the seatpost allows for a wide range of riders to fit on it), the aerodynamics of the frame (which are generally thought to be good) and the reasonable price for an all-carbon 105 bike.  Many shops stock Specialized bikes so this should be relatively easy to order.

9. Felt B2. Price: $3799.  This is the second most expensive bike on this list, but it’s worth it if you have money to spend.  The “bayonet” fork system is supposedly more aerodynamic than just a head tube, the aerobars are the best on the market and the wheels are aerodynamic enough for racing while being strong enough for training.  The geometry is suitable to most riders, and the smallest two sizes (48 and 50cm) come with 650 wheels, which makes it much easier for women to fit on this bike.

8. Giant Trinity Advanced SL 2. Price: $5050.  This is the most expensive bike on the list.  I wanted to include one of the new “Superbikes” on the list, and I chose this one because one of them (Specialized’s Shiv) has recently been the subject of some bad publicity and the other (the Cervelo P4) has already had a lot written about it.  The attention to detail on this bike is amazing.  Ultegra shifting, aero wheels, carbon fiber everything–the only thing not to like is the fact that you’re spending $5000 on this bike.  (They have a $12,000 option that includes Zipp 1080 wheels and electronic shifting, but that’s just ridiculous.)

7. Leader 735TT. Price (frame only): $399.  If you’re mechanically inclined, you can build a perfectly good triathlon bike, using the Leader frame as a starting point, for a fraction of the cost of an entry level bike.  This aluminum frame comes with a 78 degree seat tube angle, for power and comfort in the aero position.  You’ll need to spend a few hundred additional dollars on the remaining components (fork, drivetrain, wheels, etc), but if this kind of project puts the fire in your step, then seriously consider the Leader frame.

6. Trek Equinox 7.  Price: $1869.  Trek’s entry level bike is not entry level at all.  The aluminum frame is very similar in performance characteristics to their higher-end carbon frame.  Trek is as ubiquitous here in the U.S. as any other brand, so you should have no trouble finding a Trek shop and determining if this bike fits you.

5. Cervelo P2. Price: $2800.  One of the most aero bikes out there, in spite of it’s relatively entry level price.  Cervelos are the most ridden bike at the Ironman world championships for a reason.  The simple design hasn’t changed in several years, because it simply works.  This bike should definitely be on your list regardless of the amount of money you’re willing to spend–it’s that good.

4. Quintana Roo Chiquilo Women’s. Price: $1599.  This women specific bike is very similar to the Tequilo (QR’s other entry level bike), but has some modifications that female riders will prefer.  Tthe smallest size comes with 650 wheels, which is great for lady riders.  The handlebars and saddle are all lady specific, and I guess the paint job is pink so that makes it lady specific as well.  Women can be a challenge to fit on tri bikes, but the Chiquilo makes it a bit easier.

3. Giant Trinity 0. Price: $1750.  I’m showing my bias for Giant bikes here–I ride a Giant triathlon bike and I love it.  However, the Trinity stands on its own.  It’s a full aero, aluminum framed bike with 105 components AND race-ready wheels for a measly $1750.  What’s not to like?  Unfortunately, few Giant shops have caught on to the fact that their tri bikes are awesome, so you’ll probably have to special order this bike sight unseen.  Take a chance–you will probably be pleasantly surprised at the value you get from this bike!

2. Felt B16.  Price: $1999.  Speaking of value, I can say with confidence that this bike, unquestionably, gives you the most value for your money of any bike on the market today.  This is the same full-carbon frame, minus the Bayonet fork system, that’s used on Felt’s higher end bikes (such as the DA and the B2 which I mentioned earlier).

You get the Felt aerobar system, which is the best on the market in terms of adjustability, comfort and price.  You get solid training wheels, which can be swapped for race-ready wheels once you’re ready to make that additional investment.  You get 105 shifting.  You get more bike for $2,000 than most other bikes that cost $2500 give you.  Don’t ignore this bike when shopping around–chances are you’ll seriously consider it.

1.  Entry level road bike, with forward seat post and clip-on aerobars. Price: $1000-$1500.  If you ever ride with other people, do a road race or crit, commute, or basically do anything other than triathlons with your triathlon bike, you’ll find that a triathlon-specific bike is very awkward (and possibly not safe) for these tasks.  A road bike can perform any of these tasks safely and comfortably.

To use a road bike optimally in triathlons, you’ll need a forward (or zero offset) seat post and clip-on aerobars.  The aerobars help you get into the prized “aero position” around which tri bikes are designed.  The forward seatpost helps put you into a more comfortable and powerful aero position by pushing your hips forward and reducing your hip angle at the top of your pedal stroke.

The only disadvantages of this setup is that it’s a bit awkward looking, doesn’t handle quite as well as a dedicated tri bike, and requires time to switch between a regular road setup and a tri setup.  However, the advantages of this setup–price, convenience of only having one bike, and flexibility to purchase a tri bike down the road while still having a perfectly good road bike–far outweigh the disadvantages for many triathletes.

If you’re new to triathlons, you should definitely seriously consider this option for your new bike purchase.  Especially if you’re on a budget and anticipate doing other kinds of riding outside of triathlon.