FSA OS115 stem review

Light, tight and clean-looking stem

Our rating 
4.0 out of 5 star rating 4.0
GBP £99.95 RRP | USD $143.63
FSA OS115 Stem

Our review

This stem is gorgeous to look at and usefully stiff but it ain’t cheap
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This carbon fibre/CNC machined alloy hybrid is a seriously slick looking piece if you want to lose weight off your race/trail rig. 


FSA do a full-on carbon wrapped model (the OS-99 CSI at £139.99), but this stem of two halves keeps weight slightly more manageable while still turning in a good performance. 

The matt forged main body with its shiny CNC machined flutes, flanges, drillings and cutaway looks first-class. The super-thin wall construction with fat carbon fibre front plate and titanium bolt kit keeps weight down too. 

Weight still isn’t as low as FSA claim or we expected for the price, but the OS-115 is noticeably stiffer than lighter stems. We’ve been hammering it without compromise on a long-travel hardtail for months with no drama. 

The fat carbon front plate keeps a firm hold on proceedings, but be wary of the twin same-side rear clamp, as it will savage your knees if you clobber it in a crash.


There’s a wide range of sizes and angles plus flip flop decals but the high price means you’ll have to invert your piggy bank too.

Product Specifications


Name OS115 stem
Brand FSA

Weight (g) 128
Length (mm) 90
Clamp/Bar Size 31.8
Material Carbon CNC Machined
Stem Length/Reach Options 100mm 110mm 120mm 130mm 70mm 80mm 90mm
Angle 6