In chapter 10 of Lois Lowry's The Giver, what is different about the bikes after the twelve ceremony?

In Lois Lowry's The Giver, children receive a new responsibility each year during the ceremony days. At the beginning of the story, Jonas's sister turns eight, but she is mostly excited for the next year when she turns nine. Children who turn nine receive bicycles. The bicycles give children more freedom to travel around town, but they also require more responsibility because the must also take care of them. When Lily gets frustrated with her hair ribbons one morning in chapter six, Jonas reminds her she gets to start her volunteer hours at age eight and that there are many good things to receive each year. For example, Sevens receive jackets with buttons on the front rather than the back. The symbolism behind the jackets is explained as follows:

The front-buttoned jacket was the first sign of independence, the first very visible symbol of growing up. The bicycle, at Nine, would be the powerful emblem of moving gradually out into the community, away from the protective family unit (52).

The above passage also explains the meaning behind the bicycles given to children at nine years of age. By chapter 10, however, Jonas recognizes something different on his bike after receiving his calling in life during the Ceremony of Twelves the day before, as follows:

During the night the nameplate of each new Twelve had been removed by the Maintenance Crew and replaced with the style that indicated citizen-in-training (91).

The nameplates on all of the new Twelves' bikes now say "citizen-in-training." This means Jonas and his friends have, in a way, graduated from childhood and are now expected to act like adults. They still go to school, but instead of volunteer hours, they train in their decided fields of work for their future jobs. This is significant for the children because they now know which direction their lives will take; and for the community, these new citizens-in-training partially enter the workforce and contribute to society. Symbolically, Jonas and his fellow Twelves are considered adults after their ceremony and the bikes' nameplates help commemorate their rite of passage.