I own an 8 year old Alley Cat 1 speed pedal trailer attachment. I am having increasing problems with flex at the seat post attachment point plus flex onto my hybrid bike. Since this is an older trailer, have the newer ones gotten better ? Is there less flex affecting the adult rider ? I am not sure if this problem has developed due to stress/fatigue at the clamp onto my seat post of that as my 6 year old son gets bigger his pedaling effort is affecting my riding. Has anyone else out there encountered this problem ? I would appreciate feedback if the newer pedal trailers (even with 5 speeds) are better in the attachment and side to side sturdiness. Thanks in advance !