LIGHT BICYCLE AM930S I9 HYDRA WHEELSET REVIEW

DOWNCOUNTRY LIGHT, ALL MOUNTAIN STURDY

Review by Robert Johnston | Photos by Adam McGuire

Light Bicycle was one of the first companies to bring affordable carbon fiber rims to the masses. Operating direct-to-consumer – initially from their Chinese headquarters exclusively but now with warehouses in North America, Europe and Australia – they’ve been offering quality carbon wheels with price tags considerably lower than the big-name brands for years. The recent release of their new and unique AM930S rim piqued our interest, so we were stoked when they agreed to supply us with a set to put to the test on the best trails of the UK. Read on to find out how they ride, and to see what happens when you reach their limits.

THE LAB

Light Bicycle put a lot of effort into optimizing the shape of their new 29er-only AM930S to produce their take on the best handling characteristics for an all-rounder mountain wheelset. This led to the development of their unique S-Flow rim profile, with a variable overall depth between 18.1-21mm that leads to the “ribbed” inner rim shape similar to the ZIPP road wheels. But in this instance, the motive was not to improve aerodynamics (though it’s possible this is a pleasant byproduct), but to increase vertical compliance in order to deliver the most comfortable ride on the trail.

The rim is produced with the common Toray T700 carbon fiber material but bolstered with carbon fiber nanotubes in a bid to reduce vibrations and improve impact resistance (by a claimed 10%). The inner width sits at the common 30mm to pair well with tires from 2.2-2.7”, and there’s a wide 3.5mm hookless rim bead to improve impact resistance and reduce the likelihood of pinching the tire in a hard impact. Rounding out the well-considered shape of the rim is the generous 3.3mm offset and ±8 degree spoke drilling angle, giving a highly asymmetric rim profile that allows for spoke lengths and tensions to be closely matched for the strongest possible wheel build. Light Bicycle offers the AM930S in a standard layup (tested) that weighs a claimed 400g, or a lightweight layup for less aggressive riding that tips the scales at a claimed 350g. These come with a maximum kitted rider weight limit of 135kg and 90kg respectively. As standard the rims come with Light Bicycle’s BlackTek “paintless” finish, which gives a premium high gloss clear finish that’s claimed to be highly scratch resistant and “near flawless”.

Light Bicycle offers a full custom wheel building service for the AM930S, as well as offering the rims alone for those looking to build up their own set. This service allows for the rims to be customized, choosing the layup (including a flyweight front, standard rear option) and spoke count (either 28H or 32H), and the option to change the finish or add paint to the rim in the customer’s desired color. The wheelset can also be built with the customer’s choice of hubs (from a wide range of options to suit different budgets and preferences), spokes and nipples, with accompanying prices to match. We were supplied with a pair of the “paintless” AM930S standard rims in 32H, laced with Sapim CX-Ray bladed steel spokes to our chosen Industry 9 Hydra hubs with Microspline freehub and 6-bolt brake mount. These tipped the scales at 1621g total (740g front, 881g rear) without any accompaniments, and retailed for $1502 USD with the standard 5-year warranty. Rims are available to purchase separately for $289 USD each if you want to build them yourself.

THE DIRT

I was very excited and intrigued by the Light Bicycle wheelset before it arrived – outlandish items are always the most interesting to test, and the heavily engineered shape of the AM930S rims certainly sits in the outlandish category. Unsure of how they would look in the flesh, I was pleasantly surprised by their clean aesthetic that looks purposeful rather than plain wacky when mounted to a bike.

The rims were supplied untaped with a reasonable quality thin rim tape included. The finish both inside and outside the rim looked good – the rim bed was tidy and consistent, and inspecting the layup around the gloss-clear rim you can tell they’ve got their layup and compaction dialed as the fibers are neatly in line for the majority and there’s no sign of any voids (trapped air due to poor resin distribution around the carbon fiber fabric). The wheel build was dialed too, with a high spoke tension that was consistent around the wheels and clearly pre-bedded in as there wasn’t a “ping” to be heard on the first ride. Once taped, it was time to test out tire installation, and mounting up a variety of tire brands posed no particular issues. Getting the bead over the thick rim sidewall didn’t prove to be any more difficult, and once on the rim a quick puff from a track pump seated the beads without too much effort, giving a very satisfying “ping” as they popped into place.

Admittedly the “AM” moniker had led me to assume the new Light Bicycle (LB) AM930S rims were designed to take more abuse than their “downcountry” categorization. So, I set about equipping my hard charging enduro bikes with the LB wheels and some burly rubber. Unsurprisingly the LB AM930S, I9 Hydra, and Sapim CX Ray wheelset was lightning fast to get up to speed. A combination of their light overall weight and the immediate engagement and fast rolling of the I9 hubs gives a real benefit off the mark and when ratcheting up janky climbs compared with a heavier wheelset. That said, you could throw just about any lightweight rim onto a set of Hydra hubs and improve the agility of the bike – it’s the other ride characteristics that really set two rims apart, and the AM930S rims stand out for good reasons.

On the descents there’s an awesome stiffness-flex balance, with no extra perceived harshness compared with the 28h DT Swiss EX511 or 32h Nukeproof Horizon alloy wheelsets when riding hard on washboard trails and through repeated braking bumps and compressions. This lack of harshness is delivered with a reassuringly solid and connected feeling, retaining all the feedback you desire without the hand-killing harshness of some burlier carbon hoops. There’s enough compliance laterally to conform to the trail as well as any sturdy alloy enduro wheelset too, without producing disconcerting vagueness when hitting turns as hard as possible. As riding characteristics go there’s little I’d change with this wheelset, they’re truly a pleasure to ride.

The 30mm ID is now becoming the standard, and for very good reason, offering a good tire profile for the majority of 2.4-2.6” rubber on the market. The hookless bead held multiple tires from different brands firmly in place at medium pressures (down to 27psi on the rear, 25psi front for my 95kg mass) without any notions of air loss through burping, both with and without inserts. There was never an issue with the tires failing to seat straight, only easy tubeless setup and operation.

To reiterate what I briefly mentioned earlier, the Industry 9 Hydra hubs were a joy to ride, featuring incredibly quick and solid rear hub engagement that makes them some of the best money can buy. You’d forgive them for rolling a touch on the slow side given their industry-leading engagement, but they would spin for a long time both in the stand and when coasting down the trail. Luckily for me, the long testing period featured minimal ultra-sloppy riding, which unfortunately means I can’t comment on the true weather resistance and bearing durability. That’s not to say there was no wet weather riding involved – there was plenty, and it didn’t phase them one bit as you would hope – but the true Scottish slop was never part of their ride regime.

After a few months of ragging on the Light Bicycle wheelset, I was ready to give an exclusively glowing review – as mentioned they feel great with their light weight and reassuring (but not harsh) stiffness, look unique and were proving to take quite the punishment – both with and without tire inserts. The spokes had retained the same reasonably high and well balanced tensions throughout the test without any attention from a spoke key, and as you’d expect they held their arrow-straight form too. When you pair these positive points with their price tag, which undercuts the majority of the premium competition by a significant margin, the reasons for me to recommend this wheelset were stacked up.

I decided I’d take them for one final ride, fitted to a newly arrived Canyon Strive CFR that certainly has more aggressive descending intentions than LB intended the AM930S rims to see. I had a great run on a familiar trail that has a few mild g-outs with some loose rock. There was one incident where one of these rocks kicked up from the back tire as I rode over it, but there was limited harshness in the impact and I kept on riding without thinking twice. Finishing this trail, we entered a mellow jump line with some nice jumps and berms, and everything seemed to be in check, until the run-in to the final jump on the line where the rear tire felt a touch soft. I’d expected to have a minor slice or hole in the tire, or have finally hit a corner hard enough to burp the bead, but as I looked back the issue was immediately clear as you’ll see below.

Now, exactly what caused this I’m not certain. I was running a Nukeproof ARD insert in the tire for some protection, and aside from the singular minor rock kicking incident I’d not had anything to create a cause for concern during the ride. After I had realized the damage, the rim impressively held its rigidity enough to let me nurse it down the hill and cycle the couple of miles back home, which is a much kinder failure mode than the rim totally shattering like I’d experienced years back. You can see the way the crack has moved through the rim, but clearly there’s enough material running perpendicular to retain adequate structure. Should it have broken? That’s impossible to say. I was surprised for sure, but I was riding hard, I weigh more than many at 95kg/200lbs, and the randomness of mountain biking should never be ignored. It’s entirely possible that the rock moved in such a way that it exclusively impacted the now broken portion of the rim, which may have produced a similar outcome on an alloy rim. If the abuse sustained in the previous months of testing is anything to go by, then these are not a weak rim that should be ridden with caution, but perhaps their safe limits would be closer to their “downcountry” intentions.

As I write this I’ve got a replacement rim coming to me from Light Bicycle, after going through their quick and efficient warranty process. I can’t be certain that I’ve not received any preferential treatment, but I went through all the same steps as a customer would do, and within 24 hours had a tracking number in my inbox for the new rim. I’m going to hopefully take the wheelset performance to the next level, as it’s going to be re-laced with a set of the unique BERD fiber spokes. Stay tuned for a follow-up review where I cover both the new fiber spokes and the rebuilt wheelset after a further test period. I’m excited to see how these go.

The Wolf’s Last Word

The Light Bicycle AM930S rims provided an incredible blend of handling characteristics when laced to the Industry Nine Hydra hubs with Sapim CX Ray spokes, ranking right up at the top of my list for overall trail feel. The rear rim suffered from a failure on the final ride of testing, for which it’s uncertain if it was a freak accident or just the limit of the rim being found when equipped on an enduro bike instead of their aggressive trail bike intentions. But given the abuse sustained throughout the rest of the test, I’d suggest they’re plenty strong if you keep them within their designed riding limits.

Price: $1,502 USD
Weight: 1,621 grams
Website: Lightbicycle.com