The only reason to use something else for transport, like a bicycle, is for political reasons.
Besides the parliament has no power over where subway lines in Berlin are built.
It will certainly come across better to your voters than taking the limo to the train station (Berlin central station is 5 min by foot away from the parliament), which is supposedly a fairly common occurrence.
Before the Brexit mess, several senior members of the British government (and other senior politicians) would cycle to Parliament, and make sure people knew about it.
https://www.theguardian.com/environment/bike-blog/2015/dec/2...
It's also a stereotype of particular type of man: living in SW London or around London, 40+, very high income. They used to buy sports cars, but anyone can afford that, much better to spend £4000 on a bike: http://www.thedailymash.co.uk/news/society/mid-life-crisis-r...