Took our 57/47 (or close...I don't recall exactly) Trek tandem to the bike shop to get stoker kit installed. We bought it used a few weeks ago. What have you all used for shims? Obviously not all tubes are the same size and we need another shim to beef up the tube a bit. Also, has anyone had problems with the cranks coming in contact with the front derailleur - how did you remedy. There really isn't a tandem shop near us but we certainly took it to a high end shop to install - I just don't think they do a lot of these set-ups.