Critical Mass London: last friday of the month South Bank by National Theatre, 6.30pm

Usually about 2 or 3 riders have it on to update their location.

There is a 'critical maps' live tracker app. Is that used at all?

There is a Telegram channel called "Critical Mass (Live Updates channel)" which gives location sometimes using a live location and seems active.

Not be be confused with a channel started last month and called "Critical Mass" which is an anti vax conspiracy theory channel.