Here are the relevant train lines from Paris:
Paris Saint-Lazare - Rouen - Le Havre: free spaces are available for carrying your bike on board; the whole journey lasts 2hrs 15mins
Paris Saint-Lazare - Evreux - Lisieux - Deauville : free spaces are available for carrying your bike on board. At certain times, you may need to change train at Lisieux. Normally, the entire journey lasts 2hrs 20 mins
If travelling with your bike on a regional TER train, consider the advantages of taking trains outside of the rush hours to make your rail journey easier.
On Transilien trains serving the Paris area, you are only permitted to take your bike on a train before 6.30am, between 9.30am and 4.30pm, and after 7.30pm.
Find out more possibilities on Train + Vélo services across France.
