Review: Suntour Aion RC Fork

Does the Aion bring performance to the people?

Suntour Aion RC

Pulling the Aion from its box, it feels neither cheap nor especially elegant–it feels and looks like a tool that’s just meant to do a job. And that’s basically how Suntour intended it–as a fork that offers ample performance while also being affordable to the average rider.


For $550, the RC version of the Aion tested here comes with external rebound and low-speed compression adjustments. Aside from the rebound, which has a bit of play in it, all the adjusting knobs feel high quality. While the Aion has all the necessary knobs to tweak basic ride quality, Suntour cut some cost in manufacturing and construction with a solid crown and non-butted stanchions. The back of the arch isn’t machined away like on most forks, which, while adding some weight, reduces manufacturing cost and might actually be a welcome change for riders fed up with trying to clean out the tightly spaced gram-saving grooves on other forks. The arch leaves some open real estate for a meatier tire than the 2.35-inch Bontrager XR4 I had mounted up.

Suntour Aion RC

The Aion runs a 15-millimeter threadless thru-axle. To remove the proprietary Q-Loc axle, first flip the lever open as usual, then push the nut in on the opposite side to compress the flange. Turn the nut to lock the flange before pulling the axle out. To reinstall, first expand the ramped flange by turning the nut back, slide the axle in and flip the lever up. Once you’ve got it down, removing the Q-Loc axle is significantly faster than with a traditional threaded type. While Q-Loc does have more moving parts than most axles, I didn’t have any issues with it, even after several months of dusty riding.

I tested the Aion set at 140 millimeters of travel, but it is internally adjustable from 130 to 160 millimeters in 10 millimeter increments using spacers. Volume is also adjustable if you open up the fork, while the damper cartridge is a quickly replaceable sealed unit.


Suntour Aion RC Technical Specs:

– Sizes: 27.5 (130mm – 160mm), 29 (130mm – 140mm travel)
– Adjustable air pressure, low-speed compression and rebound
– Internally adjustable volume
– 34mm stanchions
– Magnesium lowers
– 15mm Q-Loc axle
– Weight: 4.7 lbs with cut steerer tube
– $550 MSRP



With the stock volume setup, the fork ramps up rapidly at the bottom of its travel. The Aion’s bottom-out resistance fooled me into thinking I was running too high a pressure, and I spent my first couple rides progressively dropping pressure until I found the fork’s bottom. Ultimately, I settled at 60 PSI with four clicks from fully open on the low-speed compression knob and 10 clicks from fully open on the 25-click rebound knob.

With this setup, bottom outs were rare–I only found the fork’s limit on ugly landings where I would expect any fork to bottom. But what distinguished the Aion from other mid-priced forks I’ve ridden is its ability to stay relatively high in its travel under without sacrificing small-bump compliance. Even while climbing with little weight on front of the bike, the fork stayed planted and pliant over small bumps, which is likely thanks to the negative coil spring. It’s not quite as supple as its more expensive competition, and dives just a bit more under braking, but overall in those departments the Aion has probably 85 percent of the performance of a Pike or Fox’s 34. The Aion also never flexed noticeably under me at 165 pounds, but I never really asked it to perform on the type of terrain that I might ride with a burlier, longer-travel fork up front. After a handful of rides, I realized that I would be challenged to distinguish the Aion from a Pike or Fox 34 in a blind test in terms of stiffness, or for that matter, overall ride quality.

Suntour Aion RCPhoto: Sam McMain

Aside from a sucking noise on the rebound stroke, the Aion ran quietly and consistently for the entirety of the test period, which involved about 30 hours of riding spread out by several weeks of hanging. The fork remained supple throughout and never blew a seal or wept oil. At 4.7 pounds, the Aion is about a half pound weightier than the stock Pike RC3 that came with the Process, but the added weight wasn’t any more noticeable than the rest of the fork’s performance. Simply put, the Aion does the job–and for the asking price, it does it damn well. For riders looking to upgrade from an OEM coil fork or build up a trail bike from scratch, the Aion should be at the top of the price-conscious list.


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