One thing I didn't understand before I got my Big Dummy is why the
Surly Spew for the Big Dummy (http://www.surlybikes.com/spew19.html)
Use a cinch strap to hold the V-rack tubes together
and tension the Snapdeck. This will help make sure
it doesn't self-eject if you hit a bump with heavy
loads in the Freeloader bags
Once I got my Big Dummy it was clear: the V-racks are loosey goosey in
the uprights. The problem is the Big Dummy has a larger ID for the
tubes used for the uprights and bridges than the FreeRad. Whereas a
FreeRadical has an ID of about 0.875", the Big Dummy has an ID more
like 0.925" That 0.050" difference makes the V-racks floppy and the
snap deck quite loose. Without alteration to the v-racks or snap
deck, the deck will fallout quite easily.
Not having any toe clip straps around I had to improvise a different
solution. What I came up with was shimming the diameter difference
with tape. I tried electrical tape first. This was a very bad idea
as all those tape edges curled back on insertion, the V-racks couldn't
go all the way in and then they would barely come out. My second
attempt and current setup is 2" wide clear packing tape. It's quite
thin allowing you to tune the thickness to just what you need.
Wrapped carefully it has only two edges and minimal glue exposure.
If you try this, it's important to start straight, wrap tightly, and
keep the tape straight in one continuous wrap. It takes a lot of
wraps to get up to the needed thickness. I wrapped mine up to about
0.918" checking with a micrometer every few wraps. The 2" width is
perfect for the rear upright where the V-rack insertion depth is 2".
In the front the V-rack goes in a bit deeper. For that I made a mark
where the top of the upright aligns with the V-rack. I aligned my
tape wrapping with that mark. The bottom front tip of the V-rack
remains unwrapped but this seems to be fine.
I have been using this arrangement for 200km (~125mi) now and it's
working well. I lost the snap deck once on a particularly bad curb
cut, but I had reinserted the deck just two blocks earlier for an
inspection, so I suspect pilot error in that event. I just inspected
the V-racks and the tape is still shiny and unworn. I really hadn't
expected it would be in such good shape. Removal and reinsertion of
the V-racks is still easy.
I have yet to try this for the bridge pieces, but I expect it would
work as well.