Velocite RT50 – Road Tubeless Carbon Clincher Wheels – Part I

There is a second (r)evolution in road cycling happening. No I am not talking about the UCI and the state of professional cycling in general, I am thinking about the technology…

While disc brakes on road bikes is grabbing most of the attention, and they will become a mainstream choice sooner rather than later – for better or for worse, the second possibly even more important advancement in the road bike technology is being somewhat overlooked. I am talking about the Road Tubeless (RT) tire and rim technology. Hutchinson Tires first released the road tubeless tires, followed shortly thereafter by Maxxis.  Maxxis has just one RT tire in their range, the excellent Padrone, Hutchinson has a whole range of tires suited for different riding conditions and riders. There are now several other manufacturers that have released or that will release more RT models shortly. I would like to thank Maxxis and Hutchinson Tires for supplying us with sample tires and sealant during our development and testing stage.

Velocite RT50 full carbon road tubeless clincher wheel in a high-tech multi-test chamber.
Velocite RT50 full carbon road tubeless clincher wheel in a high-tech multi-test chamber.

The benefits of RT technology are similar to the benefits offered by UST tubeless tires in the MTB world. RT offers better traction, more comfortable ride due to lower running pressures, potentially more stable and efficient wheels due to lower profile of the tires, lower rolling resistance, and when used with a suitable sealant RT tires and wheels offer what may be the greatest benefit of all – virtual elimination of punctures. Imagine racing and not puncturing. In any race. Ever again (within reason). Or imagine installing the tires, and removing them only once they have worn through to the casing. Every time.

In our opinion RT has an opportunity to become the default choice for any competitive rider, or for that matter any rider that also values performance and reliability. It is for that reason that we made and released what is the only full carbon road tubeless clincher wheelset currently available for purchase.

Due to our vision for Velocite RT50 road tubeless carbon clincher wheels which is high performance combined with high reliability we built the wheels using our high performance and serviceability Gram hubs. The 50mm profile and 23mm wide full carbon RT rims are laced to the Gram hubs with 24 spokes for the rear and 20 spokes for the front wheel. Rear wheel takes advantage of the 2:1 (triplet) pattern where the non-drive side spokes are double the mass of the drive side spokes in order to synchronize their times to fatigue failure. Front hubs are laced radially for optimal lateral stiffness. The 2:1 lacing on the rear wheel places 16 spokes on the drive side, improving power transfer and response as 8 spokes are at least partially engaged at all times, and there is no torque transfer through the hub body, and thus no delayed response due to the hub body twisting.

Another feature of the Gram hub is the extra wide non-drive side flange spacing. The Velocite Gram hub is the widest spaced hub currently in the market. This improves lateral stability and compensates for the halved spoke number on the non-drive side. The result is a very responsive, stable wheel that will not rub against your well adjusted brake blocks under any circumstance, regardless of your power output (track sprinters excluded…you lot are extraordinary).

The wheels went through multiple stages of development, from the hubs which entered development stage over one year ago and were first used in our Gram SL carbon/alloy clinchers to the rims themselves that were in development for about a year. Even the wheel builders were carefully researched with the end result being that the Velocite RT50 wheels are built in one of the most advanced hand built wheels workshops in Taiwan. In fact this is the same workshop that builds wheels for several USA based brands.

Each spoke is prepped and each wheel is de-stressed and tuned three times. This is of course a long and iterative process but it will result in wheels that are extremely close to their steady state. After the wheel is built it is machine checked for several quality indicators. Machine testing does not leave anything to interpretation, or ambiguity. Finally each wheel is issued with a unique serial code and packed with our accessory kit that includes spare spokes and nipples (accidents happen), special brake pads, quick release skewers and a warranty card.

In order to establish real world reliability and safety parameters the Velocite RT50 went through multiple stages of prototype live testing, and extensive machine testing to certify them for basic safety, and to identify their performance limit.

In total four tests were performed:

1. Modified EN14764 test: the wheel is loaded by 65kg (equivalent to a 110kg rider) and run over a rotor with 6 square edged bumps which is spinning at 50km/h for 1000km. Normal EN test is conducted at 25km/h which delivers one quarter of the energy compared to the impacts at 50km/h. The summed testing output resulted in Velocite RT50 wheels exceeding the EN14764 test by 320%

2. “Sprinting test”. The wheels were loaded by 65kg and swayed side to side 600 times for 20km over a smooth drum running at 25km/h.

Constant sampling temperature probe records rim brake track surface temperature while the wheel is spinning.
Constant sampling temperature probe records rim brake track surface temperature while the wheel is spinning.

3. Braking performance test – the ‘Swiss Alps descent”. The wheels were run on a smooth drum at 50km/h and the brakes were applied 70 times for the equivalent of 130m, then released. Maximum temperature of 129.4 C was reached on the 7th brake application and it remained stable for the remaining 63 cycles.

4. Final test was a test to establish the final point of rim failure due to heat. The wheel was run at 20km/h and was brought to a full stop 16 times before the rim showed signs of failure during the 16th run, reaching a temperature of 192.8 C. This is extraordinarily high and well above 170-180 C reported as maximum temperatures observed by other manufacturers during braking performance testing of their own carbon wheels. Our data that shows a maximum 129.4 C for our rims during hard, repeat braking, and the fact that they fail at an extremely high 192.8 C indicates a very high real world margin of safety.

[embedplusvideo height=”309″ width=”500″ standard=”http://www.youtube.com/v/501Q76f3whA?fs=1&hd=1″ vars=”ytid=501Q76f3whA&width=500&height=309&start=&stop=&rs=w&hd=1&autoplay=0&react=1&chapters=&notes=” id=”ep4577″ /]

In summary, Velocite RT50 are designed to be literally extraordinary: they are the only road tubeless carbon clincher wheels currently in the market, they were carefully designed from the mechanical and structural perspective and they passed some of the most rigorous safety testing in the industry.

In Part II of this post I will discuss the aerodynamics of the Velocite RT50 wheels, and their use, including tire mounting and sealant application.