The AeroCoach ARC is the world's first TT specific noncircular 1x chainring, specifically designed for the pedalling characteristics of time trials, in a full carbon aero single chainring design.

Weighing in at only 112g (54t), the solid aero carbon 1x ARC allows you to remove the front derailleur for even further aerodynamic gains due to the special tooth design to retain the chain. The ARC's subtle shape is designed to mimic the firing patterns of your leg muscles whilst riding, increasing the gearing size when you most need it.

BIOMECHANICS

Due to the higher speeds involved in a time trial, inertia and momentum is much greater than normal. This causes pedal speed to be much smoother, and means that for a time trial (high speed) large increases in gearing and dramatic noncircular shapes are not optimal:

The ARC increases gearing quickly at the beginning of the pedal stroke as this is when the main force producers activate (gluteus maximus, vastus medialis & lateralis, as well as the tibialis anterior). After this period gearing is maintained all the way through the highest torque phase before gradually decreasing down to a minimum gearing at bottom dead centre. This smooth dropoff is when the effect of gravity and the lower leg muscles come into play.

The unique time trial specific design will help increase power output by 3-5w, and allow a smoother pedal stroke than normal. Unlike other noncircular designs you can train on the ARC ring without causing a detriment to your pedal stroke and swap between round/ARC rings without difficulty. In addition, there will be little to no power inflation (<1%) when using the ARC on a crank/pedal based power meter.

ARC TT RINGS

ARC chainrings are designed for the 40-55kph speeds involved in time trialling and fast triathlon riding. These are high inertia scenarios, where pedal speed is much more consistent than situations involving low inertia (such as climbing). Therefore the ARC carbon rings are optimised with a subtle noncircular shape.

AERODYNAMICS

The ARC has a full aerodynamic design with custom long teeth to retain the chain, meaning that you can remove the front derailleur. This can save between 1-4w at 30mph depending on the size of the derailleur. Front derailleurs should not be used to shift with an ARC 1x chainring, as this will damage the teeth and will void the warranty.

INSTALLATION

We advise to shorten the chain 1-2 links, ensuring that there is still sufficient length in the largest sprocket on the rear for best chain tension. The B screw on the rear mech should also be set to improve chain tension, please refer to the manufacturer's details for adjustment.

The carbon ARC chainrings are thinner than a normal chainring, and so in some cases placing spacers in between the ring and spider will improve chainline if the chainline is less than standard. Please ensure that the chainring is protected at all times when not riding the bike, and that framesets with no wheels on are not rested with the chainring touching the ground, as ARC's teeth will protrude and may get damaged. Chainring bolts should be tightened to 4-5Nm.

SPECIFICATION

Material: Carbon fibre

Usage: Indoor/outdoor