The actual purpose of Bacchetta's B-Pivot
 

So I've been thinking about this awhile and probably don't get it. The B-Pivot stem... what's the point in it being able to move? I actually use it to help transport my bike because I can bend the handlebars way down so it's easier to fit, but what is the actual purpose? I hear lots of people swap them for rigid stems so I don't see why it's there in the first place.

That's not enough?

It lets you adjust the handlebars if you start to get shin strike.

As I get used to the Giro, I find I put the seat down to a more relaxed position. That causes shin strike so I have to raise the handlebars using the bolt in the b pivot.

It's main purpose is to help you adjust the bars to where you want them - particularly adjusting for reach to the bars. Different people ride with different seat angles, have different arm lengths, and prefer differing degrees of arm bend.

When I put mine on a bus rack, I bend it down and bungie the stem to the frame so the front wheel doesn't wobble. And combined with adjusting the angle of the handlebar and adjusting the angle of the stem, you can make both your knees and arms happy.

Our RANS tandem has a similar Terracycle Glide Flex stem. Makes it easy to fine-tune riser/bars position plus makes it much easier for the captain to climb aboard when it's pushed forward.

http://i189.photobucket.com/albums/z.../DSCN0235b.jpg

I suppose you could compare it to at 'tilt steering wheel'...why would you need the steering wheel of a car in different positions...comfort.
keep on biking

What the others wrote. You could swap stems and bars, and get your reach perfect. But if you then tilted your seat back you'd have to start all over with a new stem and bars. Or, you can use your B-Pivot, Glide-Flex, etc, to make the adjustment quick and easy.

BTW, I use tilts on some of my bikes, even though they have hamster bars. It lets me swing the bars up and out of my way for getting on and off the bike easier.

I'm not a fan of tilting stems, unless you can positively lock them in position like you can on the Lightning P38's design. I was nearly put in the hospital by the non-locking stem one on my Vision R40 when I had to do some panic braking on a long downhill grade. I had the pivot bolt snugged down pretty tight, but my weight being thrown forward was enough to pivot the stem up past vertical and I nearly lost control of the bike. If you can pivot the bars while stopped, you can certainly pivot them if you're thrown forward as I was. Be very careful if your pivoting stem is of this design.

Sounds like a problem with a very upright seat and/or weak core muscles.