Which virgin trains route is it? From Euston the pendolinos admittedly don't have much space. From KingX they have space in the DVT at one end of the train
How about a trial run? i.e show up at Euston with a bike today/tomoz and try and get on a pendolino (look for the disabled section), see what reaction you get from staff.
Which virgin trains route is it? From Euston the pendolinos admittedly don't have much space. From KingX they have space in the DVT at one end of the train