Like the idea of a wide-range single chainring drivetrain but don’t want to drop the coin for a new XX1 group?
Leonardi Factory has a solution with their 25-40T cassette adapter. It ramps up the tooth counts over the last four cogs, giving you a much larger range and lower gearing for climbing, and the part simply replaces the last section of your stock 10-speed cassette.
Word is it shifts well thanks to ramped, machined teeth, with the expected odd jump in cadence and effort between them. i-MTB and Bagnoli Bike have been testing it and report that it works quite well with SRAM derailleurs by adjusting the B-tension screw appropriately. Cassette adapters are available for both SRAM and Shimano cassettes. They’re also reporting it ends up a bit lighter than the standard cassettes!
We couldn’t find a website for Leonardi, so anyone in the know, please drop some knowledge in the comments!