Rolf Prima Ares4 FX Wheelset
The Rolf Prima Ares4 FX is the fixed-gear edition of Rolf's Ares4, offered here as a closeout. It puts the 42mm deep Delta rim profile and paired-spoke lacing of Rolf's best-selling aero wheel on US-made, fully CNC-machined high-flange track hubs with 120mm rear spacing. Rolf lists the set at 1680 grams and calls it the swiss army knife of track wheelsets.
The Ares4 FX is for the rider who wants one aero wheelset for the velodrome, fixed-gear street riding and fast fixed road rides, and wants it hand-built with a real warranty. Rolf says it balances aerodynamics with light weight and handles climbs, wind and technical riding in the city, on quiet country roads and on the track.
Paired spokes on a track wheel are about aero and stiffness under a standing start. Pairing spokes at the rim cancels the left and right pull so each spoke runs at higher, balanced tension, letting Rolf build the Ares4 FX with 20 spokes per wheel that stay true under fixed-gear torque and skid stops.
Design and construction
The rim is Rolf's 42mm deep Delta profile clincher with a 20mm inner width and 22mm at its widest. Rolf's product description refers to carbon aero rims while its spec table lists the Ares4 FX rim as a 42mm alloy clincher; we will confirm the rim material with Rolf on your order before it is built. Rolf lists the rim as tubeless compatible and ships it with rim strips.
The hubs are Rolf's US-made, fully CNC-machined high-flange track hubs. The rear is threaded for a fixed cog with lockring or a threaded freewheel, with 120mm spacing and solid axles secured by frame bolts, which Rolf includes.
Spokes are 20 front and 20 rear, bladed Sapim CX Speed, paired at the rim. There is no disc mount and no freehub; the Ares4 FX is a track and fixed-gear wheelset. Rolf includes rim strips, frame bolts and its Certainty program coverage.
How it rides
On the velodrome the Ares4 FX is deep enough to hold speed in a pursuit or points race and light enough to accelerate hard out of a standing start. The high-flange hubs give a wide spoke bracing angle that keeps the wheel stiff when you are driving a big gear out of the saddle.
On the street the 42mm Delta profile is the sweet spot: fast on open roads, but the blunt shape keeps crosswinds from grabbing the front wheel in city gaps. The 20mm inner width takes a 25mm to 32mm tire, so a fixed-gear commuter can run something forgiving on rough pavement. Rolf's pressure guidance is 120 psi maximum with a 25mm tire and 80 psi maximum with a 32mm tire on the Ares4 FX. Rolf's Certainty program covers the Ares4 FX with a five-year warranty and lifetime crash replacement, and Rolf commits to keeping replacement parts available for every wheel it has made, closeout or not.
Specifications
| Wheel type | Track / Fixed |
|---|---|
| Rim | strips, frame bolts and Rolf Prima's Certainty |
| Rim depth | 42mm |
| Rim width | 22mm, internal 20mm |
| Brake | Track |
| Spoke count (F/R) | 20/20 |
| Spokes | Sapim CX Speed, bladed |
| Hubset | Track (Threaded freehwheel/fixed) 120mm |
| Tire size | 25mm to 32mm |
| Weight | 1680g [795g/895g] |
| Includes | rim strips, frame bolts and Rolf Prima's Certainty |
This version
This page is the Ares4 FX Wheelset itself, not a custom build. This listing is the complete wheelset - front and rear together, not a single wheel.
Fit and compatibility
The Ares4 FX is 700c with 120mm rear spacing and solid axles with frame bolts, which fits standard track frames and most fixed-gear street frames with horizontal or track dropouts. Front spacing is standard 100mm. The rear hub is threaded for a fixed cog and lockring or a threaded freewheel.
Rolf approves 25mm to 32mm tires on the 20mm inner width. For the track we suggest 23mm to 25mm; for street riding 28mm is a good balance of speed and comfort. Rolf lists the rim as tubeless compatible, so the Ares4 FX can be set up tubeless with tape and valves of your own; rim strips for tubed use are what Rolf includes.
What Rolf Prima says about testing
Rolf Prima builds every complete wheelset by hand at its facility in Eugene, Oregon. The company states that all orders are built by hand there by its own builders, and describes its process as building each wheel three times with two stress cycles in the build to seat and stretch all components. Rolf Prima says hand building lets it hit uniform spoke tensions that machine building cannot match, and that its design allows higher and more targeted spoke tension than a traditionally laced wheel, which it credits with increasing stiffness and improving spoke durability by decreasing the load cycle on each spoke.
The defining feature of a Rolf Prima wheel is Paired Spoke Technology, introduced in 1997. Bringing the spokes to the rim in pairs neutralizes the left and right outward pulling forces, which Rolf Prima says allows it to build true wheels on lighter rims with fewer spokes. Fewer spokes and lighter rims are the basis of the brand's aerodynamic and weight claims. The wheel systems combine paired spokes with the Delta rim profile, internal nipples, and patented details including the Jacketed Nipple, Self-Aligning Nipple, Differential Flange Diameter and Dish Reducing Design. Rolf Prima cites eleven patents behind its technology.
Rolf Prima runs an in-house engineering and testing lab and states it uses the ISO 4210 standard as a base starting point but considers it not tough enough, so it applies its own in-house standards. Published test capabilities include an in-house drum fatigue tester it calls the Thrasher, which compresses years of riding into days; an impact test using a weight calibrated steel anvil that exceeds the UCI 40 joule requirement, striking at spokes, between spokes and at the valve hole; lateral and radial stiffness measurement of rims alone and complete wheels; brake energy, distance and temperature testing developed for carbon clinchers; wind tunnel evaluation; and field testing by sponsored athletes. The Certainty page cites over 10,000 hours of lab testing to above industry standards.
On racing eligibility, Rolf Prima explains that UCI approval only matters for mass start UCI road races, UCI cyclocross and draft legal ITU triathlon. Its standard wheels (Aspin and the Elan family) do not require approval, while most of its deeper or lower spoke count models are non standard and are listed on the UCI approval registry. Rolf Prima does not publish a fixed rider weight limit; it says every wheel has limits that involve riding style and road conditions as well as weight, and directs heavier or more aggressive riders toward stiffer models such as Vigor, Echelon or Ares6. All road wheels can be set up tubeless with the brand's tubeless kit, and adventure, cyclocross and mountain models ship tubeless ready with tape and valves installed.
Rolf Prima backs its wheels with the Certainty program: a five year warranty against defects in materials and workmanship for the original owner, lifetime crash replacement at a discount for registered wheels, a 30 day trade out or return window in the USA, replacement parts availability for any Rolf Prima wheel regardless of age, and stated service response times of same day to 24 hours on calls and email with service work resolved within three days of receipt.
Rolf Prima's videos
From Rolf Prima
Warranty and certifications
- Limited warranty — Five years from original retail purchase against defects in materials and workmanship (2016 and newer wheels), original owner, non transferable; decals and bearings two years (source)
- Certainty program — Five year warranty, lifetime crash replacement, 30 day trade out or return in the USA, replacement parts for any Rolf Prima wheel regardless of age, same day to 24 hour service replies, service work resolved within three days of receipt (source)
- Crash replacement — Lifetime crash repair or replacement discount for the original owner; wheels must be registered within 30 days of purchase; proof of purchase and serial numbers required; freight not covered (source)
- UCI approval — Non standard models (rims taller than 25 mm, fewer than 16 spokes) are listed on the UCI approval registry; Aspin and Elan are standard wheels that need no approval (source)
- Test standards — ISO 4210 used as the base with tougher in-house standards; impact test exceeds the UCI 40 J requirement; in-house drum fatigue, stiffness, brake and wind tunnel testing (source)
- Hand built in USA — All wheels hand built in Eugene, Oregon; each wheel built three times with two stress cycles; eleven patents (source)
Sources on Rolf Prima's site:
- Rolf Prima: Testing
- Rolf Prima: Paired Spoke Technology
- Rolf Prima: Our Technology
- Rolf Prima: Certainty Program
- Rolf Prima: Warranty
- Rolf Prima: FAQ (UCI, rider weight, build process)
Everything in this section is published by Rolf Prima. ProWheelBuilder is the seller, not the tester, and the wheel reaches you as the maker builds it.
A note on Rolf Prima
The Vigor is Rolf's longest-running profile and their best seller, and the ES version has been a staple of triathlon wheel choices for fifteen years. A rim shape that survives that long in a market this faddish is usually telling you something.
Ordering it from ProWheelBuilder
Rolf Prima builds each Ares4 FX to order in Eugene, Oregon, and we sell it from ProWheelBuilder in Georgia. Because this is a closeout, we confirm availability and the rim specification with Rolf when your order comes in, and we check that your frame's rear spacing is 120mm. Closeout stock moves quickly, so if the Ares4 FX is the wheel you want, order rather than wait.
If you want a track wheel with a different hub, a flip-flop rear, a higher spoke count, or a different rim depth, we build custom track and fixed-gear wheels on Astral rims, Rolf Prima's rim brand, and can quote that alongside the Ares4 FX.
Warranty
Manufacturer's warranty. Rolf Prima gives a one-year limited warranty on its wheels under normal use. Astral is Rolf Prima's rim brand; ask us and we will confirm the current terms for the exact rim before you buy.
ProWheelBuilder. This is a complete wheelset built by its manufacturer rather than in our shop, so the maker's warranty above is the one that applies to it. ProWheelBuilder's own one-year wheel warranty covers the wheels we build. We will still handle a manufacturer claim on your behalf.
Full terms are on our Policies & Warranty page.
Ares4 FX questions
Is ProWheelBuilder the manufacturer of the Ares4 FX?
No. Rolf Prima builds the Ares4 FX in Eugene, Oregon. We are a reseller and confirm the build with Rolf.
Is the Ares4 FX rim carbon or alloy?
Rolf's description mentions carbon aero rims while its spec sheet lists a 42mm alloy clincher. We confirm the rim material with Rolf on each order before it is built.
Does the Ares4 FX have a freehub?
No. It is a track wheelset with a threaded rear hub for a fixed cog and lockring or a threaded freewheel, and 120mm spacing.
What tire sizes fit the Ares4 FX?
Rolf approves 25mm to 32mm tires, with maximum pressures of 120 psi at 25mm and 80 psi at 32mm.
Can I use the Ares4 FX on the street?
Yes. Rolf describes it as suited to city streets, country roads and the velodrome. Frame bolts are included for the solid axles.
Is a closeout Ares4 FX still covered by Rolf's warranty?
Yes. Rolf's Certainty program applies: five-year warranty and lifetime crash replacement.
Not sure? Text or leave a voicemail on 470-253-0929 or email info@prowheelbuilder.com — you will be talking to the people who build wheels for a living.
