Ultralight Rims

The GCX Ultralight series wheels are some of the lightest carbon road and gravel wheelsets on the consumer market. One of the primary reasons is our advanced carbon layup. Our lightweight rims offer extremely low inertia, significantly improving acceleration.

The rims feature 25mm inner widths and 33-36.5mm outer widths depending on the model, which make them aerodynamically and structurally optimized for 30-32c tires. As a result, they outperform wider rims in terms of optimal rolling resistance, grip, comfort, and handling. The rims have modern u-shaped profiles, giving them improved stability when descending and in crosswinds.

GCX Ultralight series wheels have all passed our standard 90-joule vertical impact test, more than twice the UCI's requirement.

Decals are laser engraved, giving the wheels a unique look while saving additional weight. Learn more about laser engraving here.

See here for more information on the difference between Ultralight, Light, and Team version wheels. See why we chose 25mm inner widths.

Rim Profiles

Precision Ratchet Hubs

At Particle, we try to avoid marketing trends and tech that don’t offer real world performance gains. For this reason, we have chosen to use the gold standard of hub design, the star ratchet. We now offer two different hubs, the SR1 and the AR1.

SR1 Hubs: These hubs, which are only available for our Ultralight series wheels, are perhaps the lightest ones ever made for the newest generation of carbon spokes. The hubset is 45 grams lighter than AR1 hubs. They feature new hub-shell designs, aerospace-grade aluminum alloy, upgraded ratchets, and TPI ceramic bearings with tighter tolerances and better sealing than those from S&S, allowing for longer lifespans. Currently, the SR1 hub comes with 36T ratchets only and are only available in combination with 4th generation carbon spokes.

AR1 Hubs: These hubs are used on our base configuration. They feature a simpler design with more generic 7075 and 6061 aluminum alloy. They come with 36T, 45T, and 54T ratchet options as well as the choice between S&S ceramic or steel bearings. We offer higher engagement ratchets for no extra cost. 36T ratchets are recommended for most users due to lower rolling resistance and improved longevity. 45T and 54T ratchets are recommended for those who require higher engagement, for example in crit racing.

Both the SR1 and AR1 ratchet hub shells and axles have been machined to 0.005mm and 0.003mm tolerances respectively, making them the most precise ratchet hubs available, therefore lowering rolling resistance and improving bearing longevity. The hubs use labyrinth seals and double layer contamination barriers, so there is a significant reduction in the likelihood of ingress, effectively protecting bearings and ratchets from the elements.

Servicing is simple, as no tools are required. Star ratchets are also simple to clean and replace.

Carbon Spokes

In order to push the limits of what a performance wheelset can be, GCX Ultralight wheels come with both 3rd generation (AR1 hubs only) and 4th generation spokes replaceable carbon spokes. 3rd gen and 4th gen spokes weigh just 3.5 and 2.1 grams respectively including nipples. Our 5.2mm 3rd generation spokes offer the best when it comes to aerodynamics and lateral stiffness, while our 3.2mm 4th generation carbon spokes are the lightest spokes commercially available and offer a comfortable ride similar to steel spokes. Both spokes are less than 1mm thick. 4th generation spokes achieve such a low weight due to titanium spoke heads and threads as well as a new profile.

One thing that not well-known is that not all replaceable carbon spokes are made the same. After comparing the carbon spokes from several manufacturers, we have settled on what we feel is the future. The hubs we have chosen have closed flanges, ensuring there is no risk of our spokes popping out, which is a concern on some carbon spoke wheelsets. In addition, spokes are mechanically secured so they do not twist, ensuring they always stay in the most aerodynamic orientation. Our 4th generation carbon spokes offer significantly better compliance, giving you extra comfort with a weight reduction of 55 grams.

Our carbon spokes have been thoroughly tested and can survive more than 4000 newtons of tension, as opposed to steel spokes, which break under loads of between 2600-3200 newtons. We even provide spare spokes in the box.

Steel and Ceramic Bearing Options

One of the most overlooked parts of a wheelset is the bearings. The GCX Ultralight series comes with either S&S or TPI bearings depending on the hub. Each front hub uses large 6803 bearings, improving durability, increasing longevity, and reducing rolling resistance. Each rear hub uses a 15267 and a 6802 bearings, and each freehub uses two 6802 bearings. Our bearings use mixed contact seals to protect them from contamination, improving longevity, while offering low rolling resistance.

SR1 hubs comes with TPI ceramic bearings only. AR1 hubs are available with both S&S steel and ceramic options. The TPI ceramic bearings have improved seals and tighter tolerances, increasing their lifespan. 

For more information about steel vs ceramic bearings, please see this article.