Try the Electric Bikes !
"We booked an electric bike tour with Robb Reurings. We met at the bike shop where we were fitted with bikes and given instruction. The electric motors give you a boost and are super fun to ride -- this was our first experience with them. As mentioned in other reviews, you get to go through areas like the beach walk and parks that cars and tour buses can't enter. Great to go swooping through the city and not get totally exhausted. We did the Sagrada Familia skip-the-line tour where Robb pre-books the tickets and you enter through a side entrance. Robb's a fun, knowledgeable and kindly guy -- you won't regret booking him. The electric bikes only cost a little more than the regular bikes and it's well worth the experience. Pa, Palo Alto"
Sagrada Familia Tours - Best tour experience in Barcelona