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ROLF PRIMA EOS4 DISC WHEELSET

Astral / Rolf

$3,099.00
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Rolf Prima EOS4 Disc Wheelset

The Rolf Prima Eos4 Disc is the top-specification version of Rolf's 42mm carbon road wheel. It uses the same Delta-profile rim depth as the Ares4 Disc but is built on Rolf's US-made XST 7.0 hubset with Enduro XD-15 ceramic bearings and a ballistic ceramic coating. The set weighs 1510 grams (695g front, 815g rear) and is hand-built to order in Eugene, Oregon.

Rolf describes the Eos4 Disc as the balance point of aerodynamics and weight, and that is the rider it is for: someone who wants one carbon wheelset for everything from climbing to fast flat rides and who wants the best hubs Rolf makes underneath it. It is the wheel we suggest when a customer says they want the best all-rounder in the Rolf catalog and price is not the first question.

Paired-spoke lacing is why a 42mm carbon wheel can weigh this little with 20 spokes per wheel. Each spoke pair meets the rim together so the left and right pull cancel at that point, the rim is not flexed between single spokes, and Rolf can carry higher tension on fewer spokes. Less spoke count at the rim also means less drag, which is part of the aero story of the Eos4 Disc.

Design and construction

The rim is a carbon clincher, 42mm deep, 19.5mm inner width, in Rolf's Delta profile, tubeless compatible and taped from the factory. The Delta shape is designed to release crosswind rather than catch it, which makes 42mm a depth that most riders can use every day.

Hubs are the XST 7.0, designed and manufactured in the USA and assembled in Eugene, with Rolf's ballistic armor Cerakote coating on the shells and Enduro XD-15 ceramic bearings inside. The rear uses the T2 high engagement drive, a 48-tooth ring with three independently sprung steel pawls that Rolf rates as twice as fast as its earlier 24-tooth ring. The freehub is CNC-machined 6Al-4V titanium in Shimano HG 10/11, SRAM XDR 11/12, Campagnolo 11/12 or Campagnolo N3W.

Spokes are Sapim CX-Ray bladed, 20 front and 20 rear, paired. Rotor mount is Center Lock. Front axle is offered as 15mm thru, 12mm thru or 9mm QR; rear as 142mm thru axle or 135mm QR.

How it rides

The Eos4 Disc rides like a very good all-round race wheel with unusually free-spinning hubs. It accelerates quickly, it holds speed on rolling roads, and the front stays composed in side winds thanks to the Delta rim. The XD-15 bearings and the 48-tooth T2 ring are the details you notice over time: the wheel coasts a long way and the hub picks up without a dead spot when you start pedaling again.

It suits riders who race and train on the same wheels, riders on rolling to hilly terrain who do not want a 60mm rim, and anyone who wants Rolf's best hub without committing to a deep section. Paired spokes give it good stiffness for a 20-spoke wheel, but Rolf still names the Vigor and Ares6 as its choices for heavier, harder-riding customers. Flat-course riders should look at the Eos6 Disc or the Eos4 front with Eos6 rear combination.

Specifications

Wheel typeRoad
RimCarbon clincher
Rim depth42mm
Rim width28.5mm, 19.5mm internal
BrakeDisc Brake
Spoke count (F/R)20/20
SpokesSapim CX-Ray, bladed
HubsetXST 7.0 Ballistic armor coating T2 High Engagement Enduro XD-15 Ceramic Bearings
Front axle15mm, 12mm, 9mm
Rear axle142mm, 135mm
FreehubShimano HG 10/11, SRAM XDR 11/12, Campagnolo 11/12, N3W
Tire sizePlease refer to chart in product images
Weight1510g [695g/815g]
IncludesTaped for

About this listing

What you are buying here is the EOS4 Disc Wheelset. The choices on this page are front axle: 15mm Thru Axle Front, 12mm Thru Axle Front, 9mm QR Front; rear axle: 142mm Thru Axle Rear, 135mm QR Rear; driver type: Shimano HG 10/11, SRAM XDR, Campagnolo, Campagnolo N3W. This listing is the complete wheelset - front and rear together, not a single wheel.

Fit and compatibility

Disc brake only, Center Lock. Front: 15mm thru, 12mm thru or 9mm QR. Rear: 142mm thru or 135mm QR. Freehub: Shimano HG 10/11, SRAM XDR 11/12, Campagnolo 11/12 or Campagnolo N3W in titanium. Rolf sells a rim brake Eos4 separately; the Eos4 Disc has no brake track.

Rolf's tire chart rates its 19C and 20C road rims, including the Eos4 Disc, for 23mm to 32mm tires, with maximum pressures of 110 psi at 23 to 25mm, 100 psi at 28mm and 80 psi at 30 to 32mm. A 28mm tubeless tire on the 19.5mm inner width rim is the setup most of our customers run.

Testing, standards and warranty at Rolf Prima

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

Paired Spokes Explained (Rolf Prima)
Rolf Prima hand-built wheels in Eugene, Oregon
Rolf Prima wheel stressor: the wheel building process
From the Lab to the Trails: Rolf Prima mountain wheels

From Rolf Prima

Paired spoke lacing diagram
Paired spoke lacing diagram
Paired spokes on the build stand in Eugene
Paired spokes on the build stand in Eugene
In-house drum fatigue tester (the Thrasher)
In-house drum fatigue tester (the Thrasher)
Rolf Prima impact test rig
Rolf Prima impact test rig

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:

The figures, certificates and media above are Rolf Prima's own. ProWheelBuilder does not run these tests; we sell the wheel and stand behind the order.

A note on Rolf Prima

Rolf still fields service questions on Vector wheelsets with thirty years and more of riding on them. That is the practical case for a company that stayed in one place doing one thing: the wheel is older than a lot of bike shops and can still be sorted out.

Ordering it from ProWheelBuilder

Rolf Prima builds every Eos4 Disc to order in Eugene, Oregon. ProWheelBuilder sells it from Georgia: you pick axles and freehub, we check the combination against your bike and drivetrain, and we send the order to Rolf, who laces, tensions and tapes the set. Since the Eos4 Disc and the Ares4 Disc share a rim depth, we will also tell you honestly that the difference you are paying for is the XST 7.0 hub, the XD-15 bearings and the coating, so you can decide with clear eyes.

If you want a 42mm carbon wheel on a hub of your own choosing, or a 24-spoke build, we make custom wheels on Astral rims, Rolf's own rim brand, in our shop.

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. Because this wheelset comes assembled from its maker, the warranty that applies is theirs, set out above; ProWheelBuilder's one-year wheel warranty is for wheels we build here. Either way, a claim goes through us and we will manage it.

Full terms are on our Policies & Warranty page.

EOS4 Disc questions

Is ProWheelBuilder the manufacturer of the Eos4 Disc?

No. Rolf Prima makes the Eos4 Disc in Eugene, Oregon. ProWheelBuilder is an authorized reseller in Georgia; we sell the wheelset, verify your order and advise on axle and freehub choice.

What is the difference between the Eos4 Disc and the Ares4 Disc?

Both are 42mm carbon Delta rims with 20 paired spokes. The Eos4 Disc uses Rolf's top XST 7.0 hubs with Enduro XD-15 ceramic bearings and a Cerakote coating at 1510g; the Ares4 Disc uses XST 4.4 hubs with Enduro steel bearings at 1520g.

What is the inner rim width?

19.5mm inner. Rolf rates it for 23mm to 32mm tires.

Which axle options are available?

15mm, 12mm or 9mm QR front; 142mm thru axle or 135mm QR rear. Rotor mount is Center Lock.

Which freehub bodies can I order?

Shimano HG 10/11, SRAM XDR 11/12, Campagnolo 11/12 and Campagnolo N3W, all titanium.

Is the Eos4 Disc tubeless ready?

Yes. The rim is tubeless compatible and ships taped; add valves and sealant.

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.