SR Suntour Aion 34 Fork

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The 160mm fork market has certainly been heating up over the last few years, and there is an array of impressive top-of-the-line options available from all of the major suspension players. SR Suntour has also made serious progress during this time, its flagship Auron fork a prime example. The Aion is a mid-market offering aimed at riders looking for a complete package at a lower price point, and curious to see how this would compare to the current cream of the crop, we set out to find out.

SR Suntour Aion RC Highlights

• Travel: 150 or 160mm (ships in 160mm setting)
• Wheel size: 27.5 and 29-inch only
• Adjustments: Low speed compression, rebound, air pressure, internal air volume adjustment
• 34mm stanchion tubes
• Forged aluminum crown, magnesium lowers
• Tapered steerer tube only
• 15mm Q LOC 2 thru axle
• Weight: 2,011 grams / 4.43-pounds (27.5)
• MSRP: $550 USD

Initial Impressions

SR Suntour has done a fantastic job dressing the Aion up to look the part, rather than skimping on finishing details and graphics as is so common in the mid-priced market. The matte black powder coated lowers and crown, along with simple white lettering, give the fork a sleek, modern style that should look great on just about any frame.

It should be noted that there are no stickers (aside from the usual warning labels), so if you fancy that murdered out look you'll be out of luck with the painted-on graphics of the Aion.

After installing the fork, which went as expected, the first fiddle with the adjustments revealed knobs that were easy to turn with a positive click that could be easily felt through gloved fingers. Looks and good behavior can only take a fork so far if it can't stand up to a good old fashioned flogging out on the trail though, so it was high time to get the Aion dirty.

On The Trail

Straight away I noticed how stiff the Aion chassis felt, certainly more so than the last 34mm fork I used from a different brand, which went a long way to providing a consistent feel on my rockiest local trails. Even with full power on a 200mm rotor the front wheel stayed on track with little of the twisting or bushing flex that sometimes accompanies skinnier all mountain forks. For reference, I weigh under 160-pounds all geared up. With its solid crown and straight-gauge stanchions (compared to the Auron's hollow crown and butted stanchions) the Aion tips the scales at about 4.4-pounds, about 0.33-pounds heavier than the Auron. This is quite a bit heavier than the market leaders, but without doing a true back-to-back comparison I'd be hard pressed to say I really felt any difference on the trail. While stiffness and weight certainly matter, it's the ride quality of the air spring and the damper that will make or break any design.

Off the top the Aion is not quite as supple as some of the latest high-end offerings, though I'd argue it feels equal or better than just about every fork produced up until about two years ago at any price point. I tend to run my low-speed compression on the fairly firm side and my rebound a touch slower than your average rider, so I've been told. I had no problem tuning the compression to my liking and never really felt myself wanting for the addition of a high-speed adjustment like the one found on the Auron.

Once set, the rebound stayed consistent throughout the course of testing, though when tuned to the heavier side it did seem to have a slight effect on the compression circuit as well. I'm not sure if this is a result of my personal preferences or simply being used to a different fork that is just a touch more sensitive in the first place.

The air spring is fairly plush off the top thanks to the help of a coil negative-spring, but tends to settle a bit farther into the mid-stroke before ramping up abruptly for the last inch of travel. Adding a touch more pressure helped maintain a better ride height but at the expense of some small bump compliance and an even more abrupt ramp-up at the end.

Though not advertised, the Aion does come with a rudimentary volume adjustment in the form of a foam spacer that sits under the air cap. To increase the volume (and thus decrease the strong ramp-up at the bottom of the stroke) simply remove the spacer altogether or trim it down to suit your own preference. The latter is definitely a measure-twice-cut-once situation, as there is no way to add material after it has been lopped off.

All told, I was impressed with this fork, even after replacing what is widely considered to be the current gold-standard in 160mm suspension on my personal bike. At almost half the price, the Aion delivers much more than half the performance. If pushed to describe it in terms of other forks, I'd say it was about as supple and well sprung as any fork you could buy, at any price up until the introduction of the most recent crop of all-mountain forks about two years ago. It also offers more usable adjustment than the on/off style dampers that can still be found on many 34mm forks priced several $100s higher. So while it may not take the crown, the Aion certainly punches a few classes above its weight.

Things That Could Be Improved

The Q-LOC 2 system works well and is certainly quick, but it takes a bit of getting used to when it's new, and a bit of finesse to work once it's dirty. If your hub has a continuous 15mm width for the length of the axle, then it'll work a treat every time. But if your hubs are 15mm only at the caps and a larger diameter internally you have to be careful to make sure the Q-LOC is twisted just right so it doesn't open up and get stuck halfway inside the hub. I never had it fail on me but it did take a few tries on some occasions to get the axle out smoothly.

The air volume adjustment, while it works effectively, is poorly executed. What good is an adjustment system that works only in one direction and only one time? Including several spacers of different lengths or smaller spacers that can be attached together would allow riders to make changes more easily and as often as needed. That's small money for a big leap in usable adjustment.

Long Term Durability

We haven't had enough time on the Aion to properly test long term seal and bushing durability, but I experienced nothing of concern for the eight week duration of this test. Aside from a little light oiling of the dust seals to keep things running smooth I didn't do any maintenance. At the end of the test I popped the dust seals up to check underneath, and everything was still clean and well greased. This, and the fact that the Aion utilizes the same sealing system as SR Suntour's high-end forks, leads me to believe premature wear should not be a concern. The weakest link is potentially the Q-LOC system, but with occasional cleaning and light lubrication it too should stand the test of time. SR Suntour cut cost by forgoing fancy butted tubes and hollow crowns, not by skimping on parts vital to the Aion's performance and longevity.

What's The Bottom Line?

$550 is still a good chunk of change, but in the modern suspension market it almost counts as downright cheap. Especially when what you are getting is essentially a slightly heavier, equally attractive looking fork, with only an incremental loss in performance to Suntour's top-of-the-line Auron. Whether it is a true diamond-in-the-rough will depend a bit on your own suspension preferences and how much fine tuning you require. As is, the Aion is a solidly built and consistently good performer across a wide range of terrain. While it doesn't have all the bells and whistles of the highest-end forks on the market, it comes respectably close despite costing half as much.

For more information, head on over to www.srsuntour-cycling.com.

About The Reviewer

Lee Trumpore has been riding bikes for more than 20 years on just about every material and technology the bike industry has come up with. In more than a decade of professional DH racing, Lee won a Collegiate National Championship and was a mainstay at major North American races as well as occasionally snagging a last page result in the World Cup series. Testing prototype components and suspension setups was common during his racing days. He has a smooth, light style on the bike even while holding it wide open. An East Coast native, his favorite trails are fast and flowing technical descents with as many corners as possible and just enough moisture to keep things interesting. Nowadays, rather than racing the clock, he'd rather enjoy a rad descent after a hard pedal to the top. A closet nerd with a Master's degree in education policy Lee currently lives in Taipei, Taiwan where he splits his time teaching mathematics to the next generation of computer geniuses and behind the lens as a photo mercenary for Vital MTB and other industry clients.