Nextie Supreme Alpha carbon rim
The Alpha is the rim Nextie sends to the UCI lab. All four sizes on this page carry their own UCI wheel approval, and the lightest, the Alpha 40, weighs 290 grams on a 23mm bed. It is Nextie's Supreme edition at its most focused: a T800, T1100 and M46J layup, roundness and flatness within 0.15mm, and a five-year factory warranty.
Nextie designs and molds the rim; ProWheelBuilder is an independent wheel builder in Georgia, not the manufacturer. We build it into a complete wheel: pick the hub, spokes, nipples and lacing in the configurator and it ships laced, tensioned and trued.
Who it is for
The Alpha is for the rider who races or climbs and wants the certificate to prove the rim can take it. The Alpha 40 and Alpha 50 are the road rims, on a 23mm inner width that holds a 28 to 32mm tire round and fast. The Alpha 45G and Alpha 55G are the G versions: a 25mm bed for 32 to 45mm tires, which makes them as much at home on a gravel race as on a fast group ride. Pick the depth for your roads and the bed for your tire.
Sizes, weights and prices
4 sizes, in 29in / 700c, drilled 20h, 24h. Rim weights are Nextie's published figures; ERD is the effective rim diameter we cut spokes to, listed per wheel size.
| Size | Wheel | Inner width | Depth | ERD | Weight | Tire range | Drilling | Rim price |
|---|---|---|---|---|---|---|---|---|
| Alpha 40 | 29in / 700c | 23mm | 40mm | 557 | 290g | 28-53mm | 20 | $485 |
| Alpha 45G | 29in / 700c | 25mm | 45mm | 547 | 330g | 29-55mm | 24 | $505 |
| Alpha 50 | 29in / 700c | 23mm | 50mm | 537 | 325g | 29-55mm | 24 | $505 |
| Alpha 55G | 29in / 700c | 25mm | 55mm | 527 | 355g | 29-55mm | 24 | $525 |
How it compares
If you want Supreme construction without the certificate, the Ripple adds a rippled inner wall for stiffness on a 24mm bed and takes every drilling from 20 to 32 holes, where the Alpha 40 is 20-hole only and the rest of the Alpha line 24-hole. The Ocean 45G is the smooth-wall 45mm aero profile on the same 25mm bed as the G rims. On a budget, the Premium CRX is the closest road equivalent.
What the designations mean
Standard, Premium and Supreme
Nextie builds every rim in one of three editions. The mold is the same; the carbon grade, the spoke-bed process, the tolerances and the warranty step up with each tier.
| Standard | Premium | Supreme | |
|---|---|---|---|
| Carbon fiber | Full Toray T700 | T700 with high-modulus T800 | T800 with ultra-light T1000 |
| Spoke bed | Standard layup | Independent mold for consistent spoke-hole thickness | Advanced Single-Point independent mold |
| Roundness / flatness | within 0.25mm | within 0.20mm | within 0.15mm |
| Factory warranty | 2 years | 3 years | 5 years |
| Built for | Reliable, cost-effective baseline | Balanced stiffness, deflection control and weight | Minimum weight with maximum impact resistance |
Tier specifications as published by Nextie.
Series codes
Every size in the list carries Nextie's own series code. Road and gravel codes are width classes, which set the tire size and the aero profile; MTB codes are duty cycles.
| Supreme | Supreme is Nextie's top edition: a T800 and ultra-light T1000 carbon blend, the Advanced Single-Point independent spoke-bed mold, roundness and flatness held within 0.15mm, and a 5-year factory warranty - the lowest weight Nextie can reach with the highest impact resistance. |
|---|---|
| Alpha | Nextie's ultralight line: Alpha road (Supreme) and Alpha 36S XC (Supreme, T1000 blend, 225g) - the lowest weight in each discipline, still on a wide footprint. |
Material and construction
The Nextie Supreme Alpha is molded from carbon fiber in Nextie's Xiamen factory, in a UD (unidirectional) weave with a matte finish. Supreme is Nextie's top edition: a T800 and ultra-light T1000 carbon blend, the Advanced Single-Point independent spoke-bed mold, roundness and flatness held within 0.15mm, and a 5-year factory warranty - the lowest weight Nextie can reach with the highest impact resistance. The bed is tubeless-ready. Nextie rates these sizes for a maximum system weight of 148Kg; 158Kg; 166Kg (rider plus bike and gear).
How Nextie tests the Supreme Alpha
Nextie publishes its own lab results rather than a marketing line. Rims are impact-tested on a drop hammer to the UCI wheel-approval protocol and beyond it (a weighted hammer dropped onto the built, tensioned wheel until the rim fails, the energy recorded in joules), checked for positive and lateral stiffness under load, pulled to destruction at the spoke hole, measured for runout and roundness as a built wheel, and heat-soaked at 80°C for four hours. Every edition also carries a roundness and flatness tolerance, an ASTM riding-condition rating, a maximum system weight and a factory warranty, listed below.
Nextie publishes full lab sheets for the Alpha rims. The Alpha 40 takes 110J from a 24.5kg hammer dropped 458mm under UCI conditions, measures 188 to 193 N/mm positive and 34 to 35 N/mm lateral stiffness (references 100 and 6 N/mm), and survives five spoke-hole pull tests from 439 to 534kgf with no cracks. The Alpha 50 passes at 110J, measures 331 to 340 N/mm positive and 37 N/mm lateral stiffness, and as a built 24-hole wheel at 150kgf tension runs within 0.13 to 0.15mm for runout and roundness. The Alpha 45G takes 120J from a 24.5kg hammer dropped 499mm, with one sample surviving to 130J, and measures 265 to 267 N/mm positive and 42 N/mm lateral stiffness. All are heat-soaked at 80°C for four hours.
Nextie's test videos
From Nextie's lab
Certifications
The UCI's wheel approval procedure is the only independent certification that exists for bicycle rims: a wheel built on the rim is impact-tested and inspected under the UCI's protocol before it may be raced in UCI-sanctioned road, cyclocross and gravel events, and the certificate is published. Nextie has held UCI approval since September 2021 and adds models each year; it also states that its factory holds SGS test certification and industry production-system certifications, and it rates every rim to an ASTM riding-condition class.
Every Alpha size on this page is UCI-approved, so a wheel we build on any of them can be raced under UCI rules.
- NXT45RC Premium road rim — UCI wheel approval, September 2021 (certificate PDF)
- Alpha 50 Supreme road wheel — UCI wheel approval, 8 October 2025 (certificate PDF)
- Alpha 40 Supreme road rim — UCI wheel approval, 29 May 2026 (certificate PDF)
- Alpha 45G Supreme gravel rim — UCI wheel approval, 21 July 2026 (certificate PDF)
- Alpha 55G Supreme gravel rim — UCI wheel approval, 21 July 2026 (certificate PDF)
Source documents on nextie.com:
- UCI approval certificate, Alpha 40 (PDF)
- UCI approval certificate, Alpha 50 (PDF)
- Nextie: Alpha 40 lab results
- Nextie: Alpha 50 lab results
- UCI approval certificate, Alpha 45G (PDF)
- UCI approval certificate, Alpha 55G (PDF)
- Nextie: Alpha 45G lab results
Figures, certificates and media are Nextie's own, published on nextie.com; ProWheelBuilder builds the rim into a wheel and does not run these tests.
Weight
Weights run from 290g for the Alpha 40 to 355g for the Alpha 55G. Rim weight is rotating weight at the outside of the wheel, so a gram saved here is felt more than a gram saved on the frame. Inner widths of 23 and 25mm decide the tire.
Value
A UCI-approved rim from the big names is priced as a status object. The Alpha is molded in Nextie's own factory and sold direct, so the certificate, the T1100 fiber and the five-year warranty come without the brand premium; built here on the hub you choose, an Alpha wheel set costs about what the boutique brands ask for the bare rims.
How we build it
Choose the size, the wheel diameter and a drilling (20h, 24h), and the configurator only offers hubs, spokes and lacing patterns that can actually be built with that combination. Start a build with the Nextie Supreme Alpha and the Custom Wheel Program opens with this rim already selected; from this page, the Build button carries the size, drilling and diameter you picked straight into the build. You can also send us a rim you already own with the supply-your-own option.
Spoke head is decided by the hub, not the rim: this rim builds equally well with J-bend or straight-pull spokes, and the configurator only offers the spokes that match the hub you pick.
Warranty
Manufacturer's warranty. Nextie warrants this product against defects in materials and workmanship. The duration, conditions and claim process are set by Nextie and can change without notice, so ask us and we will confirm the current terms before you buy.
ProWheelBuilder. Our one-year wheel warranty applies to any wheel we build around this part, alongside whatever the manufacturer offers. Inside that year, broken spokes are replaced no matter how they broke, and the wheel labor is ours - truing, re-tensioning or a full rebuild. A rim or hub failure that the maker covers, we claim for you and see through; one the maker declines, we answer with an eligible replacement at 25% off current retail. Shipping both ways is yours, and components you supply yourself fall outside this cover.
Full terms are on our Policies & Warranty page.
Nextie Supreme Alpha questions
What does the G mean on the Alpha 45G and 55G?
G marks the gravel-ready versions. They sit on a 25mm inner width instead of 23mm, take tires from 29 to 55mm, and Nextie rates them for a heavier maximum system weight (166kg on the 45G, 158kg on the 55G) than the 148kg of the Alpha 40.
Which Alpha sizes are UCI-approved?
All four. Nextie holds UCI wheel approval for the Alpha 50 (8 October 2025), the Alpha 40 (29 May 2026) and the Alpha 45G and 55G (21 July 2026); the certificate PDFs are linked in the certifications section below.
Is ProWheelBuilder the manufacturer of the Nextie Supreme Alpha?
No. Nextie designs and manufactures the rim. ProWheelBuilder is an independent custom wheel builder in Georgia: we buy the rim from Nextie and build it into a finished wheel to your spec.
Can I buy the Nextie Supreme Alpha on its own?
No. We supply Nextie rims only as part of a wheel we build, so every rim is laced, tensioned and trued here before it ships.
How long will the wheel take?
Build time comes down to parts availability rather than bench time. The estimated ship date is shown in the configurator before you check out.
Not sure which size? Text or leave a voicemail on 470-253-0929 or email info@prowheelbuilder.com — you will be talking to the people who build the wheels.
