Joined: Aug 2008
Posts: 13,140
Likes: 2,162
From: Ann Arbor, MI
Bikes: 15 Kinesis Racelight 4S, 76 Motebecane Gran Jubilée, 17 Dedacciai Gladiatore2, 12 Breezer Venturi, 09 Dahon Mariner, 12 Mercier Nano, 95 DeKerf Team SL, 19 Tern Rally, 21 Breezer Doppler Cafe+, 19 T-Lab X3, 91 Serotta CII, 23 3T Strada
Hmm, I think the 520 will not allow TBT alerts with Strava Live Segments with imported routes...unless, maybe, the routes are created in GarminConnect. Check into that, and be very cognizant of the terminology, because Garmin are very specific (and I think confusing) about what constitutes "guidance," "navigation," "turn guidance," "course points," etc.
This whole category is a hot-f***in'-mess, IMO, and I don't get why. Our phones can do live TBT nav (i.e. figure out how to get you to a destination based on where you are, on the fly) and run Strava Live Segments, so why can't a cyclocomputer? Garmin's car units do live TBT nav, but not the cyclocomputers (aside from 1000)? There's the 810, but that's quite old and has its issues...
I also hate hate hate Garmin's UI. Navigating the menus and the maze of settings is a nightmare.
All of which recommends the old iPhone idea (yes, you can run nav and Strava simultaneously), if you can bear a huge phone on your bars, the short battery life, and other issues.
Wahoo ELEMNT has added TBT guidance with a recent update, so those units may be worth looking into now, though they're unlikely to be less than £250, especially since BREXIT has screwed the pooch for y'all.