In general, you will not be able to use Pitlock Skewers with horizontal dropouts due to a lower clamping pressure than cam-style quick-release skewers – in fact, even the new exposed-cam quick-release skewers on the market these days don’t hold well in horizontal dropouts. You can, however, use Pitlocks if you have a chain-line gadget like Surly’s Tuggnut. In general though, we don’t recommend using Pitlock for horizontal dropouts unless a chain tensioner is applied.