My preferred method of transportation is my bike. Of course this is not feasible for very long distances, but for all my travel within the city it is just fine. Also I own neither a car nor a bus ticket, therefore I would have to pay extra to use those.
The weather here is unpredictable at best, it can change from being sunny and cloudless to heavy rain in one afternoon. Therefore I usually carry enough gear to stay warm and dry. The following is a list of the gear that I use to ride my bike in almost any weather condition.
And with that one can keep the above business casual look even in lousy rainy weather.
First of all I would recommend a decent bike. It should have mudguards that are installed properly with metal bars. This way the water and mud does not splash high.
Also one should get sufficiently bright LED lights. A hub dynamo is a must such that you don't have to worry about batteries. Another thing that I don't want to miss any more is that the lights stay on even if I am at rest. This way I am still easily visible even when I wait on my turn at an intersection.
I don't like blinking lights or other flashy stuff. Having reasonable bright LED lights in the front and back is well sufficient and will make the other people see you, but not take too much of their attention.
Not everyone believes in bike helmets. To me they make sense and I do not mind wearing one. Actually, they are quite handy when it is raining because the visor blocks a bit of the rain over my face.
Helmets mostly differ in their weight and the venting. I used to to have one with only few vents. When you drive fast or uphill, it will become uncomfortable with such a helmet. Now I have my second Uvex Supersonic, the old one got five years old, so I replaced it. They have a lot of vents and are relatively light.
I have a helmet cover that I can quickly put over my helmet. This way the helmet and my head do not get wet. On cold days it keeps the wind out of the helmet, which makes it a bit warmer.
There is a risk of a decent bike to be stolen while you are on the go. A simple cable lock can be opened rather quickly. Better are bar, folding or chain locks. Bar locks are rather impractical to use, chain locks are a pain to transport. Folding locks go right into a little pouch on the frame and seem to be the most practical option.
In order to transport groceries or just the large set of rain gear, I use a pair or rear panniers. They are waterproof, durable and large enough to be practical.
My right pant leg regularly gets caught in the chain ring. Therefore I need some sort of cuffs to keep it safe. Just putting the pant leg into the sock somewhat works, but I doubt that it is good for the sock. Also not all socks are long enough.
For a while I used a cuff which was a solid plastic, shaped like a horse shoe. This worked nice until the plastic just fractured.
Now I have reflective cuffs. These do not stretch, which seems like a bad thing. However, this way they are very robust and do not wear like the elastic ones that I used previously. Surprisingly they usually stay in their place and do a good job.
There is a lot of clothes that make riding more pleasant. I will go through them top to bottom.
Below some temperature I get cold ears. One can get special ear warmers to attach to the straps of the helmet. These are easy to use, but they don't warm my face or forehead. I use a balaclava which is windproof and warms a little bit.
The disadvantage is that one has to take off glasses in order to put in on or take it off. Therefore it might be preferable to get some thin cap to put under the helmet and a windproof cloth for the neck.
I am a big fan of the stretch fleece jacket. It fits nicely due to the stretching nature of the fabric, it is warm, dries fast. Also it seems to be very tear resistant. When you take it out of the washing machine, you can pretty much already put it on because it moves the moisture from the inside to the outside rather well. It can be worn also during light rain, except in Bonn, where light rain usually turns into heavy rain within minutes.
When the weather is worse, I wear a hard shell jacket over it. It is advantageous if the collar of that jacket is rather high such that you can cover your whole neck and mouth in it. This way when you sit on the bike and lean forward, the collar still covers all of your neck.
When it is really cold I wear the Mammut Aconcagua jacket and a second thin fleece over that. Wearing two fleece on top of each other is not a problem, it is really warm. The only nuisance is that they stick on each other, so putting it on or taking it off is a bit uncomfortable.
A while ago I had a quilted jacket that would fit into my hard shell jacket. Since it was large enough, I had no problems with movements. I recently tried a new quilted jacket, but if you buy it fitted, it will be too tight with some movements. The secondary fleece that I have now also stretches, so there is no problem. Also fleece is significantly cheaper than quilted jackets.
The lowest layer usually are T-shirts made from polyester. These wick the moisture from my body and transport it away. This means that sweating is less annoying. Also wet garments do not isolate as good as dry ones, so this helps keeping warm as well.
During winter, my hands quickly get cold when I have to handle metal like the bike or the lock. Handling the lock with my skiing gloves is very hard. If I open the lock and then put on the skiing gloves, my fingers will already be so cold that they don't warm back up. Therefore I use thin cotton gloves for unlocking my bikes. Then I just put the skiing gloves over the cotton gloves. This makes for comfy warm hands, even on longer tours.
The cotton gloves stick to hook-and-loop fastener rather badly. It rips out the fluffy part of the fabric, eventually leaving you with just the structural mesh on the tips of your fingers. To prevent this from happening to you, close all hook-and-loop fasteners either with bare hands or the skiing gloves.
During the transition between warm and cold weather I just wear thing wind stopping gloves. There do not make the hands sweaty but still prevent them from getting too cold in the wind.
Wearing pants that are waterproof the whole day is not really pleasant. I usually carry some waterproof pants with me that I can quickly pull over my normal pants. There are other versions with a full length zipper on the side. I don't really see the advantage with the shoes that I have.
You will want to buy such pants long enough. They must cover the shoes when you pulling up your knee. Otherwise they will just collect the water and route it directly into your shoes.
When it is very cold I use skiing underwear for isolation.
For a couple years now, I the Shimano SPD system. For longer distances this is nice because you can not only push but also pull on the pedal. You need special shoes to use these. These shoes usually have rather hard soles, therefore one might not want to wear them all day.
I have pedals which have two sides, one is Shimano SPD, the other is just a flat pedal. This way I can take normal shoes to work and back. For longer rides I still can benefit from the SPD system.
For warm days, I have sandals. For medium days, I use normal shaped shoes, and for very cold days I use half-ankle boots. The latter are not produced any more, but they still serve me well.
The latter two are waterproof with a membrane. This is very nice because you can submerge the whole shoe in water without your foot getting wet. But in medium weather, the Kimon do not breathe enough. So I would probably not buy them again and get a similar model without a membrane.
With all shoes I can use shoe covers these are completely water proof and work well, especially in combination with the rain pants. The drawback compared to actual waterproof shoes is that you cannot step through puddles.