Richard Peace has this blow-by-blow description of your options for getting your bike to France by Eurostar.
Taking bikes on the London-Paris Eurostar has to be one of the most obvious ways of getting your trusty stead to France. Whilst the train journey itself is wonderfully easy and convenient, there are one or two ins and outs you should be aware of if you want to take your bike on this particular service. If you are aware of the rules in advance, it should all be plain sailing.
First of all a word in support of folders; many cyclists are put off as they think they will be wobbly or inefficient to ride or not able to carry enough of their luggage. But I have used them on the majority of trips to France via Eurostar as they they are just so convenient; not only do they make your Eurostar embarking and disembarking so much more hassle-free, they are boon if you plan to be moving around on local transport too (for example, I've taken folders on RER trains aroun Paris several times and even local buses).
Folders are slighty more twitchy to handle than full-size bikes (though most new folder riders soon adapt and don't notice this characteristic), but are easier to manoeuvre, making them ideal for city traffic. And there are plenty of speedy folders with stiff frames and fast tyres as well as models that can be loaded up for touring.
Be aware that there is a restriction on the size of folding bikes on Eurostar (see the size summary below); Freewheeling France has published several reviews of folders that are small enough to be taken as hand luggage with you on Eurostar. They are Brompton (the most portable of all folders), Birdy, BH Emotion and Tern. I've also taken electric assist versions of the Dahon Curve and Brompton on Eurostar without problems.
Whatever size your bike, you should be able to get it from London to Paris on Eurostar and vice versa. The longest size measurement is the critical one, so I've broken down the services on offer by size.
1. 85cm or less as hand luggage
This is in fact the limit for all hand luggage you take with you on Eurostar. The folder should be bagged. It's then a matter of taking it through passport and security controls as normal (it will go through the scanner so if it is right on the 85cm limit, take care putting it on the scanner conveyor belt – I know from experience it is possible for your bike to jam on the sides of the machine if you don't feed it in straight...).
If touring around on a folder, it's likely you'll have panniers and/or handlebar and seatpost bags, so using a station trolley is probably a good idea. Trolleys are distributed around St Pancras and Gare du Nord concourses but aren't always easy to find (though there should be at least one rank of them on the platform when you get off the train). You need a pound or euro coin to unlock them, in the style of supermarket trolleys. You should then be able to relock them on the platform at the other end of your journey.
Once on the train, just look for luggage space as normal; it can help if you board early and/or get a quiet train as there is more likely to be plenty of luggage space. I can't ever recall not being able to find luggage space on the train itself, however, but it's not always been close to my seat.
2. 85cm-120cm - Take your bike on the same train as you but book it in separately
This is now classed as registered luggage.
To further complicate things, it can go boxed or unboxed; either way you should call in advance to reserve a space – I've always found it best to call just before reserving a Eurostar ticket online (have the actual service you want to travel on infront of you on the screen), then once you've bought the ticket call back immediately with the ticket details to confirm the reservation.
It's always worked for me.
I've always then made sure I arrive at St Pancras International at least an hour and a half in advance to give me time to wheel the bike to the EuroDespatch office (well signed towards the rear of the station complex), before I then check in with the rest of my luggage.
Collection at Paris Gare du Nord is along the walkway at the extreme left of the Eurostar platforms, following signs ‘Bagages Enregistrés Eurostar/Geoparts’. Road access is via rue de Maubeuge
There is the option of sending your bike with Eurodespatch boxed or in a padded bike bag – Eurostar say there is more space for boxed bikes and that they can provide a box (which is included in the price). I have never used this service as it seems unnecessary, time-consuming and I don't have faith in boxes that are meant to fit all styles and sizes of bike. If any readers have, it would be interesting to hear how it worked.
COST: £30 for unboxed bikes, £25 boxed or bagged. Important: You will receive a receipt and you need this for collection on arrival – keep it safe!
3. Over 120cm
If you have an extra long bike it may need to book it on as registered baggage, as above. Boxing required. However note that tandems are specifically prohibited from being carried as registered luggage.
Note maximum weight for services 2 and 3 above is 30kg per item.
Note services 2 and 3 are not available at Ashford, Ebbsfleet, Calais, Disneyland Paris and Eurostar ski destinations, though a similar service to the above is in operation between London and Brussels.
Eurodespatch is at:
(UK) 03448 225 822, St Pancras International
(Fr) +33 (0)1 55 31 58 33, Paris Gare du Nord
Both offices open 7am-10pm daily
More information on booking bikes on Eurostar:
Richard Peace is well-versed in cross-Channel travel with his various bikes. He is the co-author of the official guidebook to the Avenue Verte, the London to Paris bike path (see his article here for us). He's also the author of Cycling Southern France (UK, US) and Cycling Northern France (UK, US).