AbsoluteBlack 40t sprocket and lockring review

Crawler cog takes a different tack from the competition

Our rating 
4.5 out of 5 star rating 4.5
GBP £62.00 RRP | AUD $115.00 | USD $92.00
AbsoluteBlack 40t sprocket and lockring

Our review

Two-piece expander cog kit that cunningly avoids the gear gaps of its rivals
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There are tons of range expanding ‘crawler cogs’ on the market these days. What sets AbsoluteBlack’s apart – aside from the intricate machining and lack of shouty, ‘look at me!’ graphics and logos – is its cunning custom lockring (also available separately).


Instead of ditching a cog from the middle of your cassette to make room for the big sprocket – and creating a noticeable three or four-tooth gap between the gears you use the most – you remove the smallest 11t cog and swap the original lockring for AbsoluteBlack’s lightweight replacement. Screw your rear derailleur’s B-tension screw in, adjust the upper limit stop and you’re good to go. The result is seamless shifting all the way up and down the block.

You lose your tallest gear, but we only missed it on the road back from the trails. This 40t sprocket doesn’t make the hills as easy as the 42t cogs offered by some competitors but it doesn’t need such precise set-up and careful shifting (or the fitting of an aftermarket derailleur cage for optimum performance) either. Constructed from 7075 alloy, ours is lasting well.


Fitting the lockring does mean that you end up making your gear range lower rather than wider, but you can always buy the expander sprocket on its own if a broader spread of gears if more of a priority than smooth shifting. It’s only available for 11-36t Shimano SLX and Deore XT cassettes though.

Product Specifications


Name 40t sprocket and lockring (15)
Brand absoluteBLACK

Material 7075