By Tom Demerly.
What makes a $1300 aluminum wheelset exceptional? I wondered the same thing when I saw Zipp’s newest race wheel, the Zipp 101. At first look it is an unremarkable looking aluminum wheelset. Then I experienced the unique and sophisticated technology. The proof is in the ride and the ride is in the technology.
The new Zipp 101 is not a normal alloy wheel. You will go faster on Zipp 101’s than on a standard wheel.
The Zipp 101 has better aerodynamics than most wheels twice its depth. It lowers rolling resistance and improves ride quality. The Zipp 101 even seems to reduce the incidence of flat tires. The improvement in ride comfort with this wheelset is greater than with a new bike frame in most cases.
The difference in performance with the Zipp 101 is profound. You feel it immediately. This wheelset is measurably faster and rides better than wheels with three times the rim depth and at significantly less weight for better acceleration and deceleration.
-It has better aerodynamics than most wheels twice its depth. It lowers rolling resistance and improves ride quality. It likely also reduces the incidence of flat tires.-
What makes Zipp 101’s so unique and better than a conventional alloy wheel?
New, more aerodynamic (low) rim shape, called toroidal spills wind at all yaw angles: Measurably faster. As fast as most 40-60mm deep wheels especially in windy conditions.
As aerodynamic as many deep section rims, but significantly lighter at 1523 grams: Better acceleration, deceleration and more responsive braking.
Better stability than deep cross section: No crosswind instability even with aerodynamic benefit.
Lower rolling resistance: Tire can deform more easily over normal road irregularities- less energy required to maintain a given speed.
Wider range of tire choices: Tires from 21mm wide to 35mm wide can be used.
The Zipp 101 is an unlikely development from a company known more for their carbon fiber disk wheels and 80mm deep section wheels. Zipp knows one thing more than anything else: Racing. They understand that the solution to racing problems aren’t always as obvious as “deeper is faster”. Zipp has a background in Indy Car and Formula 1 racing, and has a penchant for thinking outside the box. The interesting thing about the Zipp 101 wheelset is that it looks so conventional, so “inside the box”. The truth is very different. This is not a conventional alloy wheelset.
The Zipp 101 works by managing airflow to spill the surrounding layer of air on the wheel, the “boundary layer”, with less disruption. It simply moves more smoothly through the air at all angles because of its unique shape with a tire mounted.
There are few places for air molecules to detach and tumble resulting in increased drag. So, the wheel has less aerodynamic resistance than a standard wheel by far and less than many deep section aero wheels, especially in a crosswind.
“[The Zipp 101] moves more smoothly through the air at all angles because of its unique shape with a tire mounted.”
Another benefit of the unique rim width, shape and depth is that it allows the tire to roll faster with less energy. You can even run lower tire pressures for better ride quality and still have increased performance. It takes more energy to force a stiff, narrow tire to conform over small irregularities in the pavement. That energy robs speed. If the tire is allowed to quickly and smoothly deform over small irregularities in the road surface it will take less energy to move it across the pavement and it will maintain better contact when cornering allowing higher, more confident cornering speeds.
Aerodynamics are not as simple as “deeper is faster” and “narrower is better”. The new Zipp 101 acknowledges those facts. The Zipp 101 benefits from better and more complete wind tunnel testing and the ability to interpret data more accurately and in greater detail- especially in a lower speed (sub 30 M.P.H.) environment.
If there is one place the Zipp 101 may suffer, it is conspicuous appeal. There is a blanket assumption that if deep is fast, deeper is even faster. It isn’t that simple. A complex amalgam of performance features contribute to a wheel’s optimal performance across all regimes. For the crowd that wants the look of an ultra-deep section wheel the Zipp 101 is uninspiring. The performance of the wheel, however, speaks for itself. You simply have to get on them.
The specific difference in rim width is significant. The inside width of the rim on a Zipp 101, measured from inner bead to inner bead of the rim where the tire mounts, is 16.24 millimeters. A Mavic Ksyrium is only 13 millimeters at the same point. The Zipp 101 is 20% wider.
The Zipp 101 uses 18 radial laced, bladed stainless steel spokes in front and 20 spokes on the rear, cross 1 on the non-drive side, radial on the drive side. Zipp does subscribe to the thinking that the drive forces are largely concentrated on the non-drive side of the hub. Some manufacturers take a different approach by crossing the drive side spokes, but not the non-drive side.
The hubs use a stiff 17 mm oversized axle that turns on stainless steel, Swiss made precision sealed bearings. Zipp mentions their steel bearings are rounder than most aftermarket ceramic bearings and have lower rolling resistance than most ceramics. I may be on board with that- several factors degrade ceramic bearing performance in aftermarket installations. Many times the aftermarket ceramic “upgrade” bearings either don’t fit as well since they weren’t designed and sourced by the wheel manufacturer and/or they aren’t installed with the same attention to detail and precision as the original bearings. In any case, I’ll argue ceramic aftermarket bearings aren’t as effective as we originally hoped, especially with a less than perfect installation. The original Zipp stainless Swiss bearings probably are better than a ceramic aftermarket- especially if ride quality is any indication. Zipp does offer an upgrade to Si3N4 Ceramic bearings with Grade 2 balls, the highest grade available in the cycling industry according to Zipp.
Zipp uses Formula 1 grade EDM technology in hub production for a claimed 50% harder material set and tolerances “20 times greater” than standard lathe turning. In plain English- a lot of effort goes into the hub production.
The Zipp 101 is a U.S. made wheelset built in Indianapolis, Indiana. I’ve toured the manufacturing facility and it is impressive, with multiple clean-rooms and proprietary processes they wouldn’t let me photograph. Everything is handmade and computer verified.
Ride quality? You notice the difference in wheel performance and overall ride quality immediately. Specifically, you simply don’t feel the bumps as much. They are plush but not blubbery. The cornering is more secure and less “tippy” or hair trigger. The wheels accelerate very well due to the relatively light weight (I normally ride Zipp 404 clinchers, pre-FireCrest design). The wheels feel fast. Predictably, there is no cross wind turbulence.
This is an ideal wheelset for Kona, where competitors complain about crosswind instability on deep section wheels. Because this wheelset will feel more stable than deeper section wheels in a cross wind a rider may be able to stay in the aero position better on a gusty day. The wheels may be faster because they enhance your ability to stay aero. Your 60 mm deep aero wheels aren’t doing you much good if you can’t stay in the aero position because you feel like you are being blown all over the road. Additionally, these are great wheels for courses like Wisconsin, Canada and Lake Placid, where you have a lot of ups and downs. Lighter wheel weight equals easier climbing.
The Zipp 101 wheelset is a sophisticated product for people who understand that wheel performance is more than just “deeper is faster”. They adapt well to a number of terrains and are versatile for race day and training day/everyday use. Their valid performance features are faster than a standard wheel and they even improve the ride quality of the bike. There may not be the same sex appeal as a super deep, mean looking 60-80 mm deep carbon rimmed wheel but then again, sometimes it isn’t all about size…