With single speed bikes however, nutted wheels are still in demand. Some think that with the extra torque generated by only one gear, extra holding strength is also required. Thus the need for a large wrench.
-My first thought was the "Cool Tool". This was one of the first bike specific multi tools. Now the design is owned by Gerber.
It not only has a crescent wrench on one end, but a 14/15mm socket attachment. This is the tool that I carry, and have owned for over 10 years.
-Having a bunch of old tools in my bike bin, I then thought of this ol gem. It has various sizes of socket like fitting including a 15mm. But having destroyed one in the past, I am not sure that it can deliver the torque requirements of a 15mm rear axle nut (30is ft/lbs according to Park Tools).
But maybe I just had a crappy one, and one of better quality would work.
-The next tool to hit my brain was the stubby wrench. Maybe this would be a good alternative to a full size wrench. All the reliability, half the size. You wouldn't need to change up your trusty tool kit, just have a little addition. And they are so cute to boot.
-But if you are going to be caring a wrench for a single purpose, you might as well make it specific purpose, yet multi use; does that make sense at all. Introducing the Park tools single speed spanner. A 15mm stubby wrench with a six point socket, tire lever, and a bottle opener.This little guy sells for under $15 dollars, and seems built for the job.
This is a good time to throw in a short discussion on "points" of a socket. What six point socket vs a 12 point one. It is the number of possible contact locations the tool/socket can have with the nut/bolt head. A hex head nut has six sides, and thus the true maximum contact points is 6. The stubby wrenches shown above are of the 12 point variety. This does not mean that it contact the nut in 12 points but has 12 possible contact locations. This allows more indexing possibilities if you are working in a tight spot. A 12 point wrench will slip over the nut every 30 degrees apart, whereas a 6 point will only do so every 60 degrees. A open end wrench only contacts the nut in 2 points, and like the 6 point, govern by the hex pattern, indexes every 60 degrees. So which is the best? Generally a 6 point socket provides the most "grip" on a nut. Each of the six points grab more of the corner than a 12 point would. However if working in a tight spot a 12 pt might be necessary. A open end wrench is generally the worst, and most likely to round out your hex corners, but in some applications they are necessary when you cannot slip a box end or a socket over the end, such as a sensor with a wire or a nut on an all thread. If a high torque application of this type is required a flared nut tool or a sensor socket can be used, 5 point. But we will save that discussion for another time.
-Finally a little bit of warning. I would stay away from multi tools that claim to have a 15mm wrench, such as this one. I doubt that the 15mm cut out in the piece of steel will hold up.
So good luck Rob, and let me know what you choose.