Above is a conceptual sketch for a low-rider attachment for rando racks on bikes without low rider bosses.
I had been looking at different ideas for front racks for my Circle A which is really designed as a Sportif, because I couldn’t resist providing for the option of carrying a small front load in addition to the frontbag/handlebar bag that will go on the rando rack.
There have been a good number of variations over the years on the “low rider” attachments to french style rando racks. Look at this beautiful Boxer rack, which attaches to the dropout at the bottom and the small rando rack at the top:
or the Grand Bois, which is a little more contemporary as it bolts to separate low rider bosses in addition to the rando rack and the dropout:
These racks were traditionally designed for Sologne/Berthoud style panniers which differ from Ortlieb style bags in that the French bags have their attachment points at the top edge of the bag, whereas the Ortliebs mounting rail is about 3-4 inches lower. On the same rack, the Ortliebs will sit 3-4 inches higher.
Additionally, since most of the French bikes did not have low rider bosses, the bags were generally centered over the axle, rather than further back close to the steering axis as you see on modern low riders.
I like my Ortliebs and wanted to see if I could find a way to mount them lower and further back, without providing low rider bosses, partially because I think a lot of people might find the design useful, but mostly because I didn’t want to look at the empty low rider bosses for the 95% of the time that I would not have the low rack attached. Additionally, I thought there was a certain elegance to the lines of the rack that was lost when I drew it with a low rider boss.
The rack as drawn will result in the center of the Ortliebs being at the height of the axle, but pushed back so the steering axis passes through the center of the bag projected onto it (as the axis passes between the two bags, not through them).
I hope this will result in minimal wheel flop and good handling on a low trail bike.