Some municipalities require them on your bike. Aside from that, they are usually better than yelling "get the $&@;#);%* outta my way" at cars, pedestrians, and other cyclists. If you commute, it just makes sense to have a bell.
I received an email the other day for a Kickstarter project from Knog. I love Knog, and I'm not ashamed to say it. I've been using their lights on my commuter bike for a couple of years now, so when they said that they were coming out with a bell, my interest was piqued.
Most bells look like, well, bells. By that I mean the same dome shape that has been the standard for countless years. Not exactly sleek or sexy. Those two adjectives would, however, do a good job at describing the Knog Oi.
The first thing you notice, is that it doesn't look like a bicycle bell. And, that is the idea. It is meant to blend in on your handlebars, and not look out of place, no matter what bike you are putting it on.
And two different sizes: small for 22.2 mm diameter bars, and large for bars up to 31.8 mm.
The mount has been designed to not interfere with your brake and shifter cables.
Interested, like I am? Go to their Kickstarter page here, to learn more. I'll be ordering one.
Update: Their Kickstarter went live only a day or so ago, and they have already blown away their $14,000 goal.