Problem - Carrying things	Solution
I can't carry my computer / change of clothes / tools on my bike.	Put a rack and panniers on the bike.
I tried a rack and panniers, but my heels keep hitting the panniers.	Use a bike with a longer frame - the Xtracycle, a recumbent, a crank-forward bike, or a Dutch city bike.  Your heels will be far in front of the panniers, and you can also use larger bags.
My stuff gets wet in the panniers.	Use waterproof panniers.
The panniers aren't big enough.	Try a trailer.
I don't like to pack things neatly into panniers or a trailer;  I just want to toss them in and grab them out.	You need a velomobile -- but not just any velomobile.  The Cab-Bike is built for this sort of packing
Problem - Rain	Solution
It might rain.	You can ride in the rain if your bike has fenders and you have rain gear and waterproof panniers.
It might rain very hard.	In many places, it doesn't rain hard for long.  Watch the weather radar and time your trip.
It rains very hard for days at a time here.	You need a velomobile.  Velomobiles offer particularly good protection from puddles.  The water sprays up to the sides and behind while the rider is fully protected from splashes.  Some "head-in" velomobiles have windshield wipers.  Some "head-out" velomobiles offer optional roofs.
Problem - Cold	Solution
It's too cold to ride.	Cover up that Lycra with something warm.
My feet are still cold.	Use Neoprene booties over your biking shoes or just switch to platform pedals and regular snow boots.  You don't really want to be clipped in if there are icy patches anyway.
Now my hands are cold.	"Lobster" gloves are warmer, and you can even get mittens with a pocket for a warming pack.
What about my ears and face?	Scooter helmets are warmer than standard bike helmets.
I can't breathe this cold air!	If your jacket collar comes up over your mouth, you can breathe air that's warmed by your body.  There are warming masks, too.
I want to ride in a t-shirt and shorts in below-freezing weather.	You need a velomobile.  Of course, you'll still have to bring along some cold-weather gear in case you get stuck somewhere.
Problem - Stability	Solution
I might hit a patch of ice.	Watch out!
I'm careful, but it's dark, and I can't see all the ice patches.	A trike offers the same stability as a velomobile.
Problem - Wind	Solution
Headwinds slow me down.	A recumbent can give you a lower profile and let you cut through the wind.
I want to ride fast even against a headwind.	You can add a fairing and a tailbox.
It would be nice if the sidewinds would give me a speed boost.	You need a velomobile.  They can take advantage of tailwinds and sidewinds to speed you up, and they cut through the headwinds very effectively.
Problem - Parking	Solution
There's no bike parking at work.	Demand it!
Bikes get stolen around where I work.	Try to get indoor, secured bike parking.  Or buy a folding bike and just bring it inside.
The only parking places are for cars.	Sorry.  This is not a reason to buy a velomobile.  Drivers won't see it in the parking space, and they'll run into it.  There's no good way to protect against theft without something to lock it to (or preferably a place to lock it IN).
Problem - heat and sun	Solution
I get overheated when biking.	If you can't get showers at work, even just a pack of baby wipes for cooling down can help.  Save the fast riding for the trip home.  Start early.
I think I'd stay cooler in a velomobile.	You've got to be kidding!  You don't really believe that, do you?  But you might be surprised to find that velomobiles aren't as prone to overheating as you might think.  Some (Cab-Bike and Leitra, for instance), have effective air scoops for cooling.  Light-colored velomobiles can offer enough protection from the sun to offset the heating effect of exercising in a closed box.  You can also put gel ice packs on the seat and carry lots of cold drinks along.  I've ridden at 95 degrees F and stayed cool.
Problem - snow	Solution
My bike just won't go through deep snow, and it's hard to deal with traffic when everyone's crowded into one lane.	Sorry to disappoint you, but, in snow, having three wheels in three separate tracks is NOT an advantage over having two wheels following the same track.  Some days, you just have to get out the cross-country skis.
I really want to bike in the snow.	Big tires will float you over the snow, and REALLY big tires will do it even better.  A trike with two-wheel drive in back is good in snow, and a pedal-electric hybrid 2-wheeler with human power on one wheel and electric on the other is another way to do it.  Really, though, think about those skis.
Problem - boredom	Solution
I ride a recumbent for exercise, but it doesn't have any wheels.  I'd like to multi-task by going somewhere at the same time.	You can use a standard recumbent bike or trike for exercise, too.
It would be too much of a shock to exercise in the open air.	A velomobile could help there, but be sure to get one with ventilation.

Velomobiles bring their own problems, too. They don't fit into standard bike racks.  Kids are tempted to fiddle with them.  They aren't nimble, so you can't dart out of tight spots in traffic.  Most velomobiles have at least one wheel that is hard to reach for tire-changes.
Narrow or pot-holed bike trails or side-paths may not offer good routes for all three wheels of a trike or velomobile.
On ice, a velomobile with single rear-wheel drive does not get much traction.  You may have to get out and push it up a hill (not that bad, but be sure to wear suitable boots).  With glare ice, neither the velomobile nor the cars can steer or stop reliably.  You may want to stay far from other vehicles.
Velomobiles are fast, but not fast enough to mix with typical U.S. suburban traffic.  Drivers of SUV's and small trucks are unlikely to notice a tiny velomobile.  Many velomobiles have blind spots and don't feel safe in heavy traffic.
Velomobiles are heavier than bikes.   Better aerodynamics can offset the higher weight on flat ground or rolling hills (where momentum isn't lost to air resistance before you coast up the next hill), but you will notice the extra effort when climbing long rises.  You will also feel the higher weight when starting and stopping in city riding.
Velomobiles can be awkward to transport.  They are expensive to ship, and it isn't easy to bring them to a distant event.
Velomobiles are not for the shy and retiring.  They don't slide aerodynamically through crowds.  In fact, they are often slowed down by curious onlookers.

So you're saying I shouldn't buy a velomobile?  

No.  Just that you need to understand what a velomobile can and can't do.  Make sure your personal cycling infrastructure can handle a velomobile.  If you want a velomobile because you DON'T bike now, stop and think about why you don't bike.  For each reason not to bike, find out whether a velomobile is the best solution -- or whether there is a simpler answer.  If you already bike, and you think that a velomobile would let you bike more, take a good look at your bike(s) and see whether some modifications would solve your cycling problems.  Ask around to find out whether a velomobile would work better.  

One BIG advantage to remember is that many (especially the Dutch and Belgian) velomobiles are FAST!!!

We love our velomobiles, but like many other velomobile owners we still ride a variety of other bikes, both upright and and recumbent. For commuting and running errands, we found that velomobiles are a huge improvement over a road bike but offer only a small advantage over other properly-equipped bikes.  Sometimes the disadvantages outweigh the advantages.  We don't want people to spend a small fortune on a velomobile and realize that it just won't work for them.  (Of course, that would perk up the used velomobile market!)  So, if you read this and just know that you need a velomobile, find out as much as you can about all of the brands and pick the one that fits your needs.  We want to see lots of happy velomobile riders!