I rarely cycle in London and I don't know anything about the hire bikes (I keep meaning to figure them out but have never got round to it) But if I was walking it I'd drop South of the Euston Rd and wiggle through the London University area, Fitzrovia, cross Portland Place, and pop out on the Edgware Rd slightly S of Paddington then wiggle up to Paddington via the Sussex Gdns area.
Sorry I don't know road names, as I just follow my nose and navigate from memory. Tavistock Sq and New Cavendish St being two things that pop to mind.
If I was in a hurry I might walk straight down the Euston Rd, but that's a crap walk and, I imagine, a much crapper cycle. If I was in a massive hurry and jogged rather than walking I might just match
@Drago 's 30 mins, but I doubt it. It's an hour's saunter including some slack at each end.
Best of luck and let us know how it goes.