Bikestormz 2025- getting across London with bikes

[Patiencerunningthin]

Looking for advice / steer from London based people please. My 14 year old son is desperate to attend Bikestormz bike event / rideout August 16th. Likely to be in Southwark Park.
We will arrive in Euston and I’m looking for advice on getting 2 x 14 year olds and their bikes over to Southwark Park. I’ll be on foot.
The rideout travels across London and is really well organised. I’m ok with all that bit - it’s the logistics of getting from Euston to Southwark Park with bikes. My preference would be that we get there as easy and quickly as possible so I can plan it in my timings. It looks like a 55 min walk and I don’t feel comfortable with them trying to convince me they’ll find it as I stroll behind!
Looks like bikes aren’t allowed on the tube routes I need. Any thoughts from people more familiar with the journey involved.
We’re not strangers to London but usually only grappling with cases and kids- not bikes.
All suggestions greatly received.

You can take a bike on the Thameslink from Kings Cross to London Bridge. It’s about 10mins walk from Euston to Kings Cross, and then either walk (30 mins) or take another train to South Bermondsey station and walk from there.

I would imagine most people would cycle it though… would be about 20-30mins on a bike, depending on traffic.

Easiest I’d say, can you pick up a Lime bike and you all cycle together? Google maps will plan you a route and (from having taken a brief look) it will opt for cycle lanes / friendly routes where they exist.
lime bikes have a holder for your phone so you can get all set up and it’s easy to navigate.

Or Addison Lee will take a bike in some of their taxis - you’d probably need to check they are happy with two bikes, and it wouldn’t be cheap, but would be absolutely stress-free. Black cabs might take you, it would depend on the driver.

And that’s why I love mumsnet…. So far, my son’s research consists of making me watch old Bikestormz footage on YouTube. Cracking tricks and talent- but not helping my decision making about how doable it is,
Thanks so much.