Edwin Clack, 34, lives in Summersdale and used his tandem bicycle two or three times a week to take trips to the shop and get exercise.
On Friday (March 12) thieves took the Orbit tandem bicycle which was locked up to a metal post under a car port.
Sussex Police has said officers are investigating and has asked anyone with information to come forward.
Edwin's father Martin has also appealed for any information that could lead to the return of the bike.
Describing the ordeal, Martin Clack said: "It was really quite upsetting. It's hard enough for him to be able to get exercise in these times.
"He uses the tandem two or three times a week going up to the local shop and getting exercise. He was really upset last night, he was in tears after we broke it to him gently.
"All we want is the bike back, someone has cut through and taken it to get home, but its very heavy and would be very difficult to sell. It is quite distinctive as it is bright silver and it has two seats."
A spokesman for Sussex Police said: "On Saturday March 13, police received a report of a theft of a tandem bicycle from an address in Warren Farm Lane, Summersdale, Chichester.
"It is believed the theft took place between 7pm and 9pm on Friday March 12. The bike is described as large, very heavy and is sprayed bright silver with black, plastic rear guards. It is used as a disability bike.
"Anyone who saw any suspicious activity in the area that night or who has seen this bike or has any information is asked to contact police by reporting online or by calling 101, quoting 614 of 13/3."