The Chain Spotter is available in two configurations: braze-on or with an additional clamp. The braze-on Chain Spotter costs US$36 (€32), while the separate clamp comes in 31.8mm, and 34.9mm sizes for $32 (€29). Yes, that’s a total of $68, should you require the clamp-on version. While the price may seem high, it’s inline with other manufacturers forged or machined watchers also on the market.
SRAM’s unique 2.5mm adjustment screw allows for precise placement, and additional support when compared to other chain watchers — some of which flex under the duress of a dropped chain, complicating the issue — thus SRAM’s watcher does offer advantage to some designs.
SRAM claim the weight of the Chain Spotter at just 12g, without the clamp and say it’s compatible with all of their braze-on front derailleurs, Apex through the new Red models. The Chain Spotter also supports standard, compact, time-trial/triathlon, and cyclo-cross gear ratios.
SRAM's $36 Chain Spotter kit