K9 ARC angle-adjust headset review

The original angle adjusting headset cups

Our rating 
3.5 out of 5 star rating 3.5
GBP £55.00 RRP | USD $86.88
K9 ARC angle-adjust headset

Our review

The original angle adjusting headset system. It’s simple but works a treat, and it’s obviously really well made too
Skip to view product specifications

K9 kicked the angle-adjust headset bandwagon off around four years ago with the ARC (angle reducer cup) kit. You’ll need a Cane Creek spec integrated headset for this to work, but that still puts you in the offset business for less than half the price of the Angleset.


The cups have nice laser-etched guides to help you press them straight. Annoyingly, the bearing faces and outer flat faces are at an angle, so it was hard to press them in flush because the press was trying to wedge it into the head tube rather than press it in.

The low stack height of the ARC is great, meaning the front end of the bike can stay low, and the difference in head angle is really noticeable and can make a massive difference to how a bike rides. 

With the added length in the front-centre and therefore wheelbase too, stability is improved while the feeling of the steering changes slightly. A definite one to try if you’re running a 1.5in or tapered head tube and want to slacken or steepen your bike’s geometry. 


This article was originally published in Mountain Biking UK magazine, available on Apple Newsstand and Zinio.

Product Specifications


Name ARC angle adjust headset (12)
Brand K9 Industries

Description • Aluminium 6026 • Anodised & Laser Etched For A Light, Long Lasting Finish • "Zero Stack" • Cane Creek "Headset Alignment" Standard • I.S. Integrated Standard • Drop In Bearings • Low Weight o 1.5 – 70g o Fustrum – 80g • Low Stack Height 5mm • ISO 9000 Standard