Biking in Berlin is easy-- the trick is to say goodbye to your loved ones before you leave, so that you have no regrets. I merged into rush hour traffic heading into downtown. Helmets? People here didn't wear helmets when the Soviets invaded with tanks in 1945, so they aren't going to worry about helmets just because a dump truck is 18 inches from you on a cobblestone road.
There are lots of bikers in Berlin. Everything was going fine--I was following a young lady who was all dressed up for work. There are bike lanes (actual dedicted pieces of sidewalk just for bikes) so we were cruising along pretty good. The problem was, she was in too good of shape. I couldn't keep up. Then the bike lane ended. So suddenly I am "in traffic". Then I got squeezed inbetween a delivery truck and some parked vehicles. Then, in an almost comedic absurdidy, but I swear is true, someone whipped open one of the driver's-side doors right in front of me. Okay, okay, I tapped out. I slammed on the brake, dismounted the bicycle and pulled it up onto the sidewalk. In order to cope with the stares from the locals, who were wondering how I was still alive, I played it cool. I meant to go up here and look at the fruit market. I suddenly was very interested in nectarines. Nothing more to see here, people! What's next, two people carrying a giant pane of glass? Is anyone delivering a piano to the third floor of an apartment building using distracted rope pullers? When things got too busy, I just dismounted, walked my bike across the street and watched with respect at the 12 year old kid zipping along on his six speed. Get to school, you crazy kid!
The middle of East Berlin has this giant, 1200 foot space-needle that looks very 1960s and Soviet-ish. It's very cool. My destination was right next to the needle, so I took a less busy sidestreet and chugged along.
I highly reccommend the hop on hop off tour bus if you want to see a lot of something in a short time, or to get oriented with any large city. San Fransisco, Los Angeles, London, Paris-- they all have this option and you just pay a one-time fee and then you can visit all the touristy stuff. The ones in Berlin ran pretty well (not a long wait, and lots of seating). They also have defferent languages (lots of them) so you can listen to 80s muzac AND a person with a British accent describe the sights.