If you’re bringing a bike, verify cycle policies on trains; some lines restrict non-folding bikes

https://andersonmfey903.theglensecret.com/london-to-heathrow-transport-best-route-by-time-of-day-and-budget-2

If you’re bringing a bike, verify cycle policies on trains; some lines restrict non-folding bikes, so consider airport buses with luggage racks instead.