MotoMark

Although it's not specifically a trench coat, look at the Tucano Urbano Magic Parka. They are more known in the moto and scooter world for their gear, they do have a small line of bicycle specific gear. The downside is their US distribution is a bit weak so you might have to order out of Canada or Europe.

I have a couple of their jackets for scootering, they look like sport coats but they have padding in the back, shoulders and elbows as well as reflective material that stows away when you get off the scoot.

I might order a Magic Parka when we're back in italy.

jimmie65

I've got an oiled denim duster I've worn. It's OK but very heavy for cycling - and gets hot really quickly. Slick rain pants and a rain jacket work better.

2_i 

Come to think of it, Italy should be a natural source of elegant clothes for 2-wheelers. That Parka looks real good, but it is mightily expensive. Thanks for the tip! They don't list any distributors in Americas. I see that there was one next to the location in Italy I visited just a month ago. For that price you might want to try it out to be fully convinced that you want to dive in. I will look for opportunities in the future but practical chances of running into any of their distributors, at least those listed, in any travel, seems bleak.

2_i 

I started conversing with the retail branch of Tucano Urbano and they do not ship to US. To make things worse, many of their dealers seem to cater only to motorized riders and skip cyclists.

MotoMark

I got my Tucano Urbano gear from Scooter Crazy Ltd in the UK. Shipping costs to the US were reasonable so if they can get their bicycle gear you could try them.

2_i 

Many retailers that claim to carry Tucano Urbano carry only their motorcycle and scooter gear, but not bicycle. As Tucano's on-line branch would not ship to US, I asked them to ship the ordered Magic Parka to a European address ahead of my scheduled travel to there. The Parka seems outstanding. Once the weather becomes more suitable for the Parka, allowing a serious trying out, I hope to post some review.

brianinc-ville

I ride in a trenchcoat sometimes. It's OK. If you don't button it all the way to your knees, your thighs get wet; if you do button it to your knees, it's hard to pedal. It's definitely no substitute for rain pants.

My wife wears a rainwrap (i.e., rainskirt) from Georgia in Dublin and loves it. I've been trying to convince myself that my masculinity can handle it, 'cause it really seems to be a great solution -- more protection than a trenchcoat, less annoying to take on and off than rainpants.

zacharyhoyt

I have full plastic fenders on my bike and wear a poncho when it rains. It's a large heavy one, some kind of military surplus so it doesn't tear easily. I sit on the back end of it, and the front end drapes down over my handlebars. The only tough part is getting my head into the hood of the poncho and my bike helmet, I have to take the helmet off, put it in the hood, and then put the poncho on and buckle the helmet strap. I stay dry above the knees this way, except in very strong winds, and the only thing that gets me wet below the knees most of the time is cars driving through puddles as they pass me.
Zach