How wide is too wide, is hookless pointless, are carbon spokes worth it and what aero innovations are coming next? We ask Parcours’ Dov Tate the big questions about road bike wheels

“You’ve got to be more than just ‘faster’ because everybody is doing faster now,” says Dov Tate, the founder of UK wheel brand Parcours. 

“A wind tunnel will tell people how fast they will go but now we’re looking at a way to quantify how stable they are,” he continues. “But there’s no unit for handling stability. There is for drag. Most people understand what a watt of drag is. I want to be able to put a relatable figure on stability. Is a saving of 3.5 watts worth £1,000? But if it’s 3.5 watts plus 15% improved stability how does that change things? And what does that 15% feel like?"

Three years ago Tate, an Oxford-educated engineering graduate, worked with Nottingham Trent University to develop a differential rim profile that he arrived at via real-world studies using marine wind sensors attached to the front and rear axles. 

Parcours was first to market with a wheelset - the Parcours Strade - that featured a wide, U-shaped front rim paired with a narrower, more V-shaped rear. His testing had shown that the ‘dirty’ air hit the rear wheel at an overall shallower angle compared with the front, in clean air, and the Strade was optimised using data collected with the marine sensors and validated in the wind tunnel.

Now, Tate has started working on what he believes will be the new crucial measurement for the best road bike wheels along with watt savings - handling stability. He talked to Cycling Weekly exclusively about how he plans to implement it. This time using accelerometers fitted to bikes with different wheels and wheel combinations and again tested in the real world, again with Dr Steve Faulkner and Nottingham Trent University’s sports engineering department.

“Essentially the way we tested it was to fit an accelerometer to the bike, fit the wheels that we’re testing and then ride an out and back with a controlled effort aiming to maintain power, speed, position. Runs are done back to back so in theory weather conditions should be close to the same and the idea is that if you run enough of the tests it normalises.

“We used just one on the edge of the handlebar because that's where you get the most motion. One of the biggest challenges with the accelerometry data was trying to squelch out the ‘noise’ from turns and bumps. It has taken a fair amount of time to get to that point. And we had to set a threshold so that an acceleration below a certain G-force doesn't count as an ‘oh sh** moment.”

Tate explains that alongside the data from the accelerometers the test riders were asked to fill in a questionnaire with a ‘perception scale’.

“The idea is that when you mark your perception you can score it numerically. The questions are designed to cross-check each other: how stable does the bike feel? You can cross check that by ‘how safe do you feel?’ and you can cross check that by ‘how much effort is needed to concentrate?'"

When the testing is complete, the aim is to be able to accurately give riders options for a range of scenarios. “So a more nervous rider may choose to 'bank' the improved stability and keep with their existing front wheel, maintaining aero benefits. Whereas a more confident rider may choose to offset that improved stability and run a deeper/faster front wheel for the same level of stability,” Tate explains.

"From a design perspective, that means that we can potentially go a little further than say we have already with the Chrono Max front wheel and say that if paired with a Disc² rear we can 'afford' to reduce handling stability a little more without going too far for riders but with the option of a faster front wheel.  More than likely this would be deeper to be faster."

Course modelling for wheel choice

Concurrently with the accelerometer testing, Parcours has been doing more testing with the marine wind sensors which could make up the other half of the picture - modelling courses and weather conditions that could in the future accurately give riders wheel options for a particular race.

Tate took the wind sensors to the Ironman World Championships in Hawaii last month and was able to demonstrate that wind conditions on Kona’s famous Queen K Highway almost exactly matched a flat ride to Windsor he did earlier in the year.

“We’ve been proving that we could rely on our existing data library to model roads that we've not been to,” says Tate.

The modelling of the course and the conditions, says Tate, come from the 75,000 data points taken by the wind sensors in the original project. 

“So we can say, let's take all of my data points and standardise it to a ride speed of 30kph. Or we can take all of our data points and standardise it to a 40kph wind speed. We can say to a rider, these are the yaw angles you'll be looking at and this is what you'll optimise [wheel choice] around and we can do that based on 75,000 data points from all sorts of different rides - so you can model a scenario that we've not tested.”

Meet Parcours' founder Dov Tate

Meet Parcours' founder Dov Tate

Dov Tate

Dov Tate graduated from the University of Oxford with a mechanical engineering degree in 2008 and initially took a job in banking in the City.

Having played hockey at a high level at school and at university (he made the Welsh national squad) the sports bug bit again before long and he took up cycling and triathlon. However, having punctured on tubulars, he realised there was no good-quality, affordable clincher alternative and the idea for a business took shape.

In 2016 he quit his banking job and founded Parcours. Six years later, he watched his wheels being ridden at the front of the Ironman World Championships by Parcours-sponsored athletes. And, he says, there's so much more to come.

Wheels optimised for different speeds

The best skinsuits are optimised for different speeds and other parts of the bike should be too, according to Tate - something else that has just emerged from his review of the original wind sensor study.

“With the wind sensors we found that as well as a difference in yaw angle, there's also a difference between the apparent wind speed at the front and and the apparent wind speed at the rear. By the time the airflow reaches the rear wheel it has slowed down essentially,” explains Tate.

“So not only should you be designing for different wind conditions in terms of yaw angle at the rear but also for different wind conditions in terms of the airspeed.

“This is important because airflow characteristics are defined by the Reynolds number. The Reynolds number is determined by a number of factors including the flow speed as well as things like the shape and length of the object. So the Reynolds number of the flow of the air at the front wheel is different from the rear wheel. 

“If you look at the 3D-printed Pinarello track bike with the different features on the frame, those features will interact differently with the air at different Reynolds numbers or wind speeds - so it's why on skinsuits they talk about why this suit is faster for riders at 50kph whereas if you're riding at 60kph you need a different suit. There are different skinsuits designed to perform best on the road, for time trials, pursuits and sprints on the track. You have different features on the legs versus the arms because the arms are stationary and are in cleaner air; the legs are in dirty air and they're moving.

“That extends beyond the body to the equipment, and will have implications for our future rim designs.

"This is still quite new. If we’re looking at a TT wheel we need to be looking at a wheel that’s optimised around a higher speed than a gravel wheel. It will be another input that goes into the design process."

Parcours recently launched its new Chrono, Chrono Max and Disc² wheels, which it says are its fastest ever wheels, clearly a motivation for Tate to continue a publicity campaign around them - and indeed the stability testing is focused on those wheels - but is it a sensible idea to give away the details of your new project before you’ve even published the data? Doesn’t he risk it falling into the hands of what he calls ‘Big Wheel’?

“I always get asked why am I sitting here talking publicly about it when it’s something that applies to any brand of wheel and they might steal my ideas. 

“But as a brand we are always transparent: we can't go public and say running a disc wheel makes you 20% or 30% more stable without showing or numbers, and if that means other people copy it or use it then so be it.

“It also keeps the pressure on us as a business to say if we publish this I have two years to use it because that's how long it takes people to reverse engineer something.

“But we’ll always have first-mover advantage. From a brand perception people always say, oh, I’ve seen that somewhere before.

“And it keeps us honest because we can’t sit around relying on something for 10 years and getting complacent. There are some brands that are onto the same design philosophy and have done similar research but that just validates what we’ve done.”