Excellent quality Colorful Fixie Gear Bike Fixie Wheels - 18TSRX Oversized pulley wheel System – Kactus Sports

12/18T Oversized pulley system

Save up to 45% friction resistance, compare to 11T pulley

Ceramic bearing version saves more than 2.2 watt power on average, compare to original transmission

Full carbon fiber cage

18 tx suitable installed on SHIMANO XTR/XT/SLX M9000 / M8000 / M7000GS/M6000GS

Full 7075 aluminum alloy CNC lightweight pulley

18TSRX suitable for SRAM X1 XX1 GX NX

Ceramic bearing version hybrid ceramic bearing version NSK steel bearing version

Weight: 59g

Ceramic bearing version weighs 1.2g less.

Why replace derailleur pulley

First, replace the original pulleys with these would improve the weak stretch of the original set, and make the up and down chain tension between guide wheel and cogs much more adequate.

Second, the number of contact tooth or control tooth between chain and cogs of 17T is more during gear shifting, the more contact, the stronger the control power. 

Third, after redesign the cage’s rotation curve, the distance between upper guide wheel and the cogs is improved.

Long story short, with all the features mentioned above, you would save 2.2 watts or more with each pedaling. That’s the equivalent of shaving 100g off a 10KG bike.