These cups provide a solution for Trek Speed Concept frames requiring a smaller outside diameter cone cup than pre-installed on the trainer. While the small cone cup (pre-installed on trainers manufactured after December of 2009)* will fit into the speed concept carbon frames, it does rub. So, making a cone cup that has a smaller outside diameter fits better and prevents the carbon from getting marred.
*While the small cone cup will fit the aluminum framed Speed Concept series bicycles, we recommend using this specially-machined cone cup on carbon-series bikes. This cone cup will clear the frame flange and not mar the carbon.
