The Direct Mount Adapter was initially developed for standard mountain bike frames with 68/73mm wide bottom bracket shells, but the need was much greater for the "snow bike" market, where the 100mm wide bottom brackets make front derailleur applications a little difficult. So we did both: our Direct Mount Adapters clamp around the seat tube to allow for the use of Shimano high direct-mount front derailleurs on frames with either 68/73 or 100mm wide bottom brackets.
Technical Details
AL-6061 construction
34.9mm clamp with shims for 31.8 or 28.6mm seat tubes