Can't comment on T5 in particular but BAA has a policy of free parking for motorcycles at BAA airports.
From the BAA website :
Motorcyclists can park free of charge at Heathrow in dedicated motorbike parks.
Riders should not use the car parking bays.
Terminal 5: Next to the short stay car park.
Please note that for security reasons, motorcycles will be removed if parked anywhere other than the designated areas.
Originally Posted by
NeverFirst
And finally, although I'll probably leave my helmet with the bike, can one take a helmet through security as hand baggage? A search on FT brings up a number of different experiences, depending on airline/airport around the world.
From the BAA website :
Can crash helmets be carried through security?
Yes, but please contact your airline as some may operate additional restrictions.