The Gnomish Lexicon of the 1910s had a noun lobrob “a gallop - the sound of horse’s feet” as an elaboration of G. lob “run, gallop (of animals)” (GL/54). The meaning of the second element is unclear, but might simply be an onomatopoeic variation of the initial element.
Neo-Sindarin: Since I retain ᴺS. lob- “gallop, ✱lope” for purposes of Neo-Sindarin, I would retain the noun ᴺS. lobrob as well.
The Gnomish Lexicon of the 1910s had a verb G. lob “run, gallop (of animals)” with a past form lompi (GL/54), clearly the equivalent of ᴱQ. lopo- of the same meaning in the contemporaneous Qenya Lexicon under the early root ᴱ√LOPO (QL/56).
Neo-Sindarin: Derivatives of √LOP continued to appear in Tolkien’s later writings, such as N. lobor “horse” and Q. lopoldë “rabbit”. I would therefore retain ᴺS. lob- to describe the four-legged run of these and similar animals, meaning “gallop” or “lope”.