Wonderful news, Sammy -- All congratulations your way on the Nomad frame's arrival! You must be over the moon with joy.
As for the racks...
I have tried and tested a number of rear tubular steel racks, including the Surly Nice Rack (Rear), two Tubus Cargo Evos, a Tubus Logo Evo (the Evo editions are the newest and have investment cast bottom mounts, where the bolt head fits into a well. The rack is stiffer as a result), and Thorn's Expedition rack.
In summary, I found the Thorn Expedition rack to be the most rigid laterally and against diagonal (yaw) pressure. It just does not sway under really heavy loads compared to the other racks. It is really tough, it is heat-treated, and the weight and tube-wall thickness of the front strut crossmember indicates it is made of thicker-walled tubing than the Tubus racks. Of course, it allows mounting with 6mm bolts to the Nomad's dual 5mm-to-single 6mm lower rack adapter mount, and the top stays are solid stainless steel and must be bent into position and then trimmed with a saw to fit. It is a
really solid rack. It also has the greatest number of crossbars on the top deck, contributing to lateral rigidity as well as providing a generous number of lash points that also help prevent a load from herniating through the rack to press on the rear mudguard. Last, the Thorn rack has a greatly extended top deck to get the taillight out from behind your panniers so it is most visible form the side and rear, and it has a detachable, easily modified universal adapter plate to take a variety of LED or dyno taillights.
Overall weight is not too different, due to the design. In my tests, the Surly was the least rigid against yaw input (lateral diagonal loads imposed at the rear corners), due to the very thin mounts. The Tubii were in-between. I found all these rear racks to be equally rigid under vertical loads. All handled reasonable loads very well and did not cause or contribute to handling problems in practice, but displayed difference in my test environments. The differences were virtually indiscernible at reasonable touring loads and became more apparent when supporting very heavy loads.
A quick Forum search should pull up most posts related to Tubus racks, the Surly Nice Racks (Front and Rear), and Thorn's Expedition and Low-Loader Mark V racks.
I presume I can mount the Expedition using 5mm bolts, and the Logo Evo using 6mm bolts, but can someone confirm?
Yes: You can indeed use either 5mm or 6mm bolts on the Thorn Expedition rack or the Tubus Evo-series Cargo and Logo racks, but they are all much more rigid if you use 6mm, and the effective cargo rating is increased as well. The Nomad has 6mm frame/fork bosses and the rear adapter uses two 5mm bolts to support a 6mm mount. The adapter also allows the lower rack stays to sit a good bit wider than if they were attached directly to the dropouts, aiding bracing angles. In my opinion, the adapter is really worthwhile.
On the Cargo Evos I had and Logo Evo I have, mounting is accomplished with supplied cylinder-head 5mm allen bolts. The lower bolt head sits in the well formed by the investment cast "dropout" at the rack's base, and rides on a small-diameter, thin flat washer the same size as the head. Tubus left just enough room on the Evo versions of the Cargo and Logo to take the threaded shaft and head of a 6mm allen bolt. Attached are photos I took just a few moments ago, showing a 6mm bolt in place. The holes in the adjustable top stays are also drilled for 6mm. Again, 5mm are supplied and can be used as well as 6mm on the recent Evo series of these racks.
The Logo Evo does hold the load lower and the load can also be placed farther to the rear for heel heel clearance (pretty much a non-issue in this case, given the Nomad's generous chainstay length). It is also a pretty rack in my eyes, made of nice curves. Lowering the bag mounting rail means the cap-tops on Ortlieb's Packer-series panniers extend less far above the rack's top surface. The top deck of the Logo is very narrow compared to other racks (this is how Tubus chose to triangulate this rack against lateral sway), but it makes for a smaller platform to support rack-top packs and such (mine tended to wobble on the Logo, but was dead-solid on the Cargo and Surly's Nice Rack (Rear) and of course, on Thorn's own Expedition rack. The light mount is a buried a bit behind mounted panniers, so it doesn't show as well from the side as it would on the Thorn. In my tests, the Cargo Evo had better resistance to lateral and yaw loads than the Logo Evo, it has a wider top deck, and the Evo model of the Cargo has a closed front loop "return" (looks like a handle) so it appears more finished than the original Cargo. The Logo has no return, and the already narrow top deck tapers further at the front. The advantage is you can stuff rack-top loads further under the overhang of the saddle, so long as your thighs clear. The Evo editions of both the Cargo and Evo have a revised mounting system for the upper struts that is lighter than on older models, just as secure, a but more versatile, and easier and quicker to adjust. I think the features of the Tubus' Evo editions are enough of an improvement to choose over the still-available older models if you are buying new.
Up front, I went with Thorn's Low-Loader Mark V panneir racks and have been very happy with them, transferring the same rack from my Miyata 1000LT to Sherpa and now the Nomad. The Tubus Duo is also nice; l I don't know if it will accept 6mm mounting bolts. After all my testing, I ended up with a Thorn Expedition/Thorn Low-Loader Mark V combo, and am very pleased with the result.
Hope this helps.
Best,
Dan.
