Now even if you roll with Boost spacing on your mountain bike, you can set up your ride on an indoor Saris Trainer with a Saris Trainer Thru Axle Adaptor for 148 x 12mm axles. Be aware though that these adaptors are meant exclusively for Saris trainers, and are not compatible with CycleOps “PRO” or PowerSync trainers. Nor should you use the adaptors when riding outside. The Saris Trainer Thru Axle Adapter is designed for indoor use on Saris trainers only. Super easy to set up, the thru axle adaptor for Boost spacing makes it possible to keep your fitness level high even if the temperatures are staying way too low.