Originally Posted by 3alarmer

...before you buy and install fenders, you need to decide how big a tire you want to put on there. The simplest and cheapest fender sets that work well for me ( I have all sorts of fenders on bicycles), are probably the ones made and sold as full road fenders by SKS. They are usually easy to find on Amazon and ebay, but the wider the tyre you use, the sider the fender needs to be. And there is a lot of clearance on your bike, but it's not unlimited. With 27" wheels on there (and I personally like 27" wheels), you probably need to do some measuring, with the tires mounted first.

Or you can work backward, mount the fenders, and then measure to decide the biggest tire you can run with them. SKS-Germany Blue Mels Reflective Bicycle Fender Set

If you have zero experience with mounting fenders on a road bike, you might want to go someplace for some experienced help.