I have noticed some questions about upgrading the Trek 720 touring bike. This is some of my experience with my bike.

I purchased a Trek 720 frame in 1984. Using the components from a Schwinn 10 speed, I now had a complete bike. Over the years I upgraded the brakes from caliper to cantilever (added braze-on) to v brakes and now to disc brakes. I never had a problem when I switched from 27 inch to 700c wheels. I went from 10 speed to 27 speed. It is easy to expand the rear bracket to accept a 135 mm 29er 9 speed 36 spokes with disc brake. I had a frame builder in Squim, WA braze on the disc brake bosses on the rear and original fork for $75.00 per braze on for a total of $150.00. I use Avid BB7 mechanical discs and I love how they perform. I added upright handle bars with speed odometer, lights, fenders and bell. I am 72 years old and I ride this bike at least 5 days a week from 6 to 50 miles using a Brooks saddle with springs. It is a very comfortable strong bike and well balanced when fully loaded. The bike has been repainted twice.

For anyone with doubts about adding disc brakes, I love the setup on my bike. No more grinding of the rims when on dirt roads in wet weather and the bike stops when I want it to. If you like the 720 specs and can find a decent 720 frame the right size for you, this may be the way to go. It may be cheaper than a custom job.