Originally Posted by HarborBandS

In case anyone is reading this and thinking the Checkpoint is still "dead", the webpage was put back pretty quickly, and they now list clearance for 40mm tires on the SL5 and ALR5 frames. The aluminum frames don't have IsoSpeed, so that probably wasn't a factor in the change of "official" tire clearance.

I have test ridden a SL5 and put my somewhat heavy (for a cyclist) body in to some sprints, and didn't notice any flex in the IsoSpeed from my pedal strokes, even when standing and sprinting hard. But FlashBazbo has me realizing I need to ride this bike again before making a purchase. Or maybe they'll make the IsoSpeed adjustable on future Checkpoint models in 2020, er, 2021. LOL.