Barbie is a great biking companion, in the main predictable and well mannered. She did put on her turbo boosters when we first took off, but I told her 'whoooooah' and she slowed down. She did resist the pressure from the lead a little, pulling outward, which affected my balance a bit.
Anyway, she seemed to enjoy it, so I think I might invest in a 'Springer' - especially if I can find one at a reasonable price!