Eurostar

according to eurostar: “Bikes can be taken on the direct train from London to Amsterdam departing from St Pancras International at 08:31 only.” https://www.eurostar.com/us-en/travel-info/travel-planning/luggage/bikes call eurostar to make a bike reservation at +44 (0) 344 822 5 822, or by emailing EuroDespatch@eurostar.com

the phone rep said there are three direct trains a day.

cannot do 1715. can do 7:16am and 11:04am must drop bike off day before at luggage dispatch office. assembled bike is 55quid if you book it far in advance, it costs less. Since Im booking for wednesday it will cost 55. if I go on the 1104 train, I must be there at least 90 minutes before. there are only TWO assembled bike places per train. if reserved in advance, it must be reserved at least 48 in advance over the phone. The only way to do it sooner than that is in person at the station. then I need to go to the station today. Must go to the st pancras station. Representative cannot see if there are any spaces available.
you could drop your bike off one day and pick it up in amsterdam the next day. there is availability on the 21st for the bike i could go from london to brussels with the bike, then I would need to eurostar would cover the cost of the damage for the bike.

https://www.eurostar.com/rw-en/travel-info/travel-planning/luggage/bikes

https://www.freewheelingfrance.com/planning-a-trip/taking-bikes-on-eurostar.html