Never say never again. When we started nplus2 cycles in 2019 it was for many reasons an easy decision for us to only focus on disc brake compatible wheels for road riding and racing. And you don’t need to look into a crystal ball to predict that in a few years we all will ride exclusively on bicycles with disc brakes when it comes to performance-oriented riding.
Advantages of disc brakes.
Using disc brakes comes with many more advantages than just better stopping power that the vast majority of manufacturers stopped offering rim brake-equipped road bicycles for good. Further benefits of disc brakes are that you also can build and ride better wheels that are…
- …lighter. Less material can be used around the bead hook(less) since you do not need to dissipate heat.
- …stronger. The bead hook(less) section can utilize a similar carbon and layup used for the rest of the rim focussing on strength, and not hardness and heat management.
- …faster. The rim shape can be optimized towards aerodynamics and not around a brake track.
- …more durable. Your wheels will last longer. Sweat, tears and rain mixed with dirt is a powerful abrasive when it gets trapped between the brake pad and the rim, sooner or later grinding away carbon layers.
Blast from the past.
However, then are these weekends when we pedal our hearts and lungs out on one of SoCal’s many group rides where we see a shrinking, but persistent number of high-end road bikes still using rim brakes. Many of them are too nice and too expensive to retire them just yet, and well worth squeezing out a few more years of riding and racing. I am one of these riders sitting onboard a “rim-braked” 2013 Cervelo R5 that was in addition, or better said subtraction, designed for 23mm tires. Well, I guess we didn’t know better.
The NEW R55 RB.
Since there are almost no manufacturers of premium carbon wheels for the use with rim brakes left, and since there is some serious demand out there to blow new high-performance life into older steeds we decided to offer a rim brake version of our R55 for this not so nichy niche.
We picked our deepest rim size because aerodynamics beats lightweight 9 out of 10 times, and of course because the R55 looks ridiculously good on any bike.
To overcome the aforementioned challenges of a rim brake design we are not only taking advantage of advances in carbon manufacturing, but also chose design elements that improve heat management and aerodynamics.
Graphene. Adding graphene to the brake track significantly enhances the thermal conductivity of the rim. Graphene is a 10 times better heat sink than e.g. copper giving the braking surface metal-like properties in the area of most heat generation.
Hookless bead. A hookless bead allows to incorporate more graphene into the brake track since it is about 1 mm thicker than a hooked bead and simply adds more material bulking up the brake track.
Omitting the bead hook also creates a smoother tire-rim transition. The Airflow becomes less turbulent around this interface resulting in reduced translational drag and a faster wheel.
Textured braking surface. The braking surface has machined grooves. Not only does this massively improve stopping power in the dry and even more in the wet, it also increases the braking efficiency. You get the same deceleration in a shorter amount braking time and therefore preventing massive temperature spikes the rim has to deal with in the first place.
Internal nipples. The nipples are hidden inside the rim and kept out of the wind. The elegant transition of the spoke into the rim provides minimal surface further improving the aerodynamics by reducing rotational drag.
Internal nipples require smaller spoke holes. Therefore, the carbon structure is minimally interrupted and the rim strength enhanced. The internal nipple head also distributes the up to 130kgf onto a much larger surface compared to traditional nipples. This significantly reduces the stress around the spoke hole and results in a stronger nipple-rim interface. And last but not least, internal nipples are compressed and not pulled on their pivoting heads. This makes them extremely reliable and allows for bombproof builds.
Tires: W.A.M, tubeless, pressure.
When chatting to customers, the best way to determine what wheels will work best for them is to ask what tire size they are planning to ride. Therefore, each of our wheels are designed around a certain tire size that will give you the best performance for their intended use.
The R55 RB is aero-optimized for 25mm tubeless tires like most aero wheels, and should optimally be ridden with 25mm tires. I know, I know, 28mm is what we all should and want to ride, but read me out, please. Like a magic trick, omitting the bead hook and a 22mm internal rim width will let a 25mm tire “balloon up” to about 28mm. There are 26 or 27mm tires out there and they can work great as long as the Width As Measured (W.A.M.) is about 28-29mm. Keep in mind that most brake calipers and frames of this era won’t have much more clearance that would allows for tire bigger than 28mm.
Empirically, the rim should be about 105% the width of the tire to keep the airflow laminar and attached. This criteria is met by using a 25mm tire and will give you the best tire-rim transition with a perfect leading edge slicing through the wind. In addition, the increased tire footprint provides higher speed at lower pressures, excellent grip when cornering and more comfort.
We do not recommend the use of tires smaller than 25mm, in fact we highly discourage you to mount them on the R55 RB. The high pressure required to ride small tires does not work well with a hookless design. We also encourage you to ride the R55 RB with maximal 75-85psi when using 25mm tubeless tires depending on the system weight. It is backed by a lot of research that less (pressure) is more – more speed, more traction, and more comfort. Gone are the days when tires were inflated to 120psi or when you couldn’t push down the plunger anymore.
The boring (but very important) R55 RB specs.
Intended use: Road, Road Racing, Criterium, Triathlon
Rim depth: 55mm
Inner rim width: 22mm
Outer rim width: 30mm
Aero optimized tire size: 25-27mm –> W.A.M: 28-29mm
Textured braking surface: Improved braking in dry and wet conditions. Less heat build-up.
Tubeless optimized design: Lower rolling resistance. Better grip. More comfort. Increased puncture resistance.
Hookless bead design: Lighter rims. Increased impact resistance. Better aerodynamics.
Spokes: Bladed Sapim CX-Ray for low rotational drag
Spoke count: 20 (radial) front; 24 rear
Internal nipples: Sapim brass. Superior strength. Improved aerodynamics.
Bearings: Standard, or ceramic bearing upgrade p/b Kogel available
Weight: from 1400 grams
MSRP: from $1295
Available with White Industries T11 or Hope RS4 hubs in many colors. Will ship in about 7-14 days.
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