What are your thoughts on a mechanical disk brake upgrade for a two year old Disk Trucker? The whole system (calipers, disks and levers) not just calipers. Looking for brakes that brake well, are rugged and can handle a loaded touring bike going downhill.

I am not familiar with the specific brakes on the disc trucker. But on my Lynskey, I wanted better grip on my rear disc brake, it came with semi-metallic pads. I bought some really cheap resin pads. And I ran them in as recommended. Very happy with the result. That said, they fade on a really tall hill, the semi metalic probably do not fade. I carry a spare set of the resin pads on a tour, as resin pads wear faster.

Yesterday I installed Avid BB7 road calipers on a new frame. Mated to a pair of old Shimano Exage road levers and running Jagwire compressionless housing. They work very much like rim brakes and are very controllable. With that being said, if you want the best mechanical calipers get the Paul Klampers(as I have been told, no actual experience with them). If you want something more affordable, the Tektro Sypre calipers work well. I installed them on my son's bike. Only issue with them was the constant rain of Seattle killed them within a year. They need to be serviced, I guess. Without a doubt, the Spyre is a much easier set up when compared to the BB7.
BB7 uses resin pads. If you are using a higher friction pad, be sure the rotor is spec'd for that type of pad. My rotors are not, thus I stuck with the stock resin pads.

This is the first I have heard of Spyre problems from rain. I put one on my Lynskey in the rear nine years ago, trouble free ever since. That bike does not see much rain, but the tours I have done with that bike had several all day drizzly kinds of days.

LIve in Seattle for a year and commute, road ride and some trails, then you will experience the curse of the rainy northwest. They rusted up internally. No big deal, the frame cracked shortly after that and was junk. The crack came from being hit by a car 12 years prior. Cracked right at the point of impact.

perhaps...

The catalog I looked at shows TRP Spyre calipers come stock with the bike. If so, I'd keep them. I finally upgraded the Avid BB-7s on my bike to Spyres, and am very pleased.

BB7s are a very good choice. I’ve tried all three… BB7, Spyre (actually Spyke), and Klampers. The Klampers are gorgeous and work very well but I haven’t found them to be 3 to 5 times better than the BB7 as the cost would indicate.

Spykes are okay but the adjuster screw can be delicate and is often too tightly screwed into the body from the factory. The allen socket rounds out easily and then must be drilled out. They work fine but the pad adjusters screw is a weak point.

I like the bb7, but found them a bit fiddly to set up. I have a set of Shimano road mechanical disc, not sure of model number, that came with a 5700 equipped bike. They have been very good. Easy to install and set up, minimal adjustment necessary over time.

The BB7 calipers are a pia to set up in the road version. Once dialed in they work well. There are certain steps to take when setting them up, and there are utube videos that go thru the details. I had Avid disc brakes on an Anthem X1 mountain bike and never liked them, especially in a panic stop. Simply too powerful. The BB7 brakes behave much like a rim brake and are very easy to control.
The only reason I now am running disc brakes on a touring bike is due to getting caught in a rain storm and having to hit the binders to make a emergency stop, but was unable to get stopped in time. Didn't get hurt as I had a way out, but it scared me into getting discs for this season.

I'm considering Growtac Equal Brakes (available in post or flat mount) for the Jamis Renegade S1 build. There's something about modern mechanical discs on mechanical shift steel frame bike that makes me smile.

TRP HY-RD + Jagwire compressionless. Run mine with Shimano Centerlock Ultrega IceTech rotors, Tektro Ergo levers and barcon.

My cable TRP Spyre for my Rohloff14 has resin pads and compressionless cable stops instantly anytime, the first pads went 5,300 miles. EASY to set up. I have a homemade mount and homemade track dropouts. Bike was 120 lbs on both tours. LOL. A tour bike NEEDS dyno lights anyway.
For the front brake NOTHING beats my SA XL-FDD dyno DRUM brake. Stops and shines like new after 34,000 miles, now on it's 3rd bike. Unbreakable with Dyad rims and 2.3/ 2.0 spokes. Now with 700 x 37 mm tires.
Pads/ shoes still not finished. And dammit the replacement I bought is 5 years old already. That's when I also built a new one for my tour bike.
NO other brake is set and forget. I hear some mud race guys wear out disc pads in ONE ride. LOL Hilarious.
My CCM now has compressionless housings for the front rim and small SA drum 3 speed, so it stops far better too.

My Co-Motion Pangea Rohloff came with the TRP Spyrs. I wanted beter stopers so I tried the TRP Hy/RDs. I went with the Paul Klampers after that. The Klampers although expensive are strong and sturdy.

Am happy with my Growtacs and adjustable-pull Avid levers.
pics in my album.