Tech feature: The return of non-round rings, June 7, 2006
A very elliptical comeback
For over a century, the vast majority of riders have been content
to use conventional round chainrings. But there have always been a few
product designers, manufacturers and riders who have claimed, often passionately,
that some sort of non-round shape works better with the biomechanics of
the human body. With the recent increased profile of non-round rings under
riders such as Bobby Julich and Marianne Vos, James Huang takes
a look at the ideas behind them.
It's hip to be oval
The basic idea - a larger
effective gear in the power stroke ...
Photo ©: James Huang
…and smaller at top and bottom
Photo ©: James Huang
Rotor USA's booth at the Sea Otter Classic saw a steady stream of traffic
this year, not just from those who were curiously amused by Rotor's new,
elliptical Q-Rings, but also many who were there specifically to purchase
a set. Non-round rings were once viewed as novelties at best or completely
pointless at worst, but in the last couple of years they have enjoyed
a renaissance, thanks in part to some high-profile credibility in the
pro ranks. Recent successes include that of Marianne Vos, who took the
elite women's world cyclocross crown on a set of Q-Rings, as well as ProTour
contenders Bobby Julich (Team CSC) and Alexandre Vinokourov (Astana-Wurth),
who won last year's Paris-Nice and took the bronze at the 2004 world time-trial
championship, respectively, while turning over non-round rings by O.Symetric.
Why not just use round chainrings?
On the face of it, it's hard to see what's wrong with regular round chainrings.
After all, every professional race in the world has been won on round
rings and top riders have demonstrated time and again that it's certainly
possible to produce extraordinary power outputs very efficiently while
using them. Moreover, countless cyclists worldwide have logged millions
of collective miles on them with nary a complaint and from a mechanical
perspective, they are also arguably the best way to construct a bicycle
However, human physiology is not necessarily designed for pedaling in
perfectly even circles. Measurements of force output demonstrate that
a rider is substantially stronger while pushing down through the middle
of the pedaling stroke that at the top and bottom of the rotation. Many
cyclists spend years combating this natural tendency and perfecting their
technique to drive through these so-called 'dead spots' in an effort to
maximize their pedaling efficiency. Entire companies have even been built
on products solely designed to help riders train their muscles to achieve
that perfect 'spin'.
The idea behind non-round rings is to use mechanical rather than physiological
means to improve a rider's pedaling efficiency and/or power output by
carefully varying the effective chainring size throughout the pedal stroke.
The rings are generally oriented so that the cyclist is pushing a bigger
gear during the downstroke, when the power output is greatest, and a smaller
gear at the top and bottom of the stroke to speed the transition through
the dead spots where power output is greatly reduced. For example, Rotor's
standard outer road ring has 53 teeth, but because of its elliptical shape
it is effectively a 56-tooth ring in the power stroke, and a 51-toother
as the rider's feet pass through the dead spots.
As revolutionary as it sounds, the thinking behind these rings is not
new. Non-round rings date all the way back to the late 1800s and Roger
Durham (of legendary component maker Bullseye) was promoting the concept
back in 1970. More recently, Highpath Engineering in the UK
has quietly been producing its elliptical Eggrings for over 15 years,
while back in the mid-1980s Shimano put its considerable weight behind
a modified elliptical chainring shape called Biopace.
Photo ©: Russ and Nancy Wright
Nearly all of these rings (with Shimano's Biopace being the notable exception)
follow the same basic design philosophy of increasing the gear in the
middle of the pedal stroke. Their manufacturers claim that modern biomechanical
information has been incorporated into the designs of the newest crop
of non-round rings in order to maximize their benefits. Although the
approaches taken by different companies may slightly vary, all of the
current offerings seem to have some sound empirical data behind them.
Suppliers and supporters of non-round rings tout a wide range of benefits
to their use. Rotor cites an
independent study that claims its Q-Rings result in a 4.1 percent
power increase at a similar level of effort when compared to round rings,
as well as a 9.1 percent decrease in lactic acid production and a 2 percent
reduction in heart rate. Similarly, O.Symetric
claims a 5-15 percent power output increase (again, with similar levels
of effort) resulting in a 3 percent increase in speed. Both manufacturers
also mention a few less quantifiable advantages, such as reduced knee
strain resulting from the reduced effort in the high-stress dead zones,
more consistent power output, and improved traction in off-road situations
particularly at low cadences.
Blame it on Bobby
It's uncertain how many people would have referred to Bobby Julich as
a trend-setter a few years back, but he has undoubtedly acted as the spark
for the non-round ring revival. Julich's chainring set-up was seen as
goofy-looking when he first started using O.Symetric rings, but no one
can argue with his recent results, especially in time trials - an Olympic
bronze medal speaks for itself. Of course, whether or not those results
are the direct product of running non-round rings is a different story.
Photo ©: Mark Zalewski
While there are still far more round rings out there than non-round,
but the idea is picking up steam. Other pro riders seem prepared to give
the concept a try; O.Symetric says that ten riders have confirmed to the
company that they will be using its rings in the Tour de France this year
and David Cañada used Rotor's Q-Rings in last year's Tour de France. Moreover,
non-round rings have been very well accepted in the triathlon scene: three
of the top six male finishers at last year's world championships were
on Rotor Q-Rings.
Rotor says that this acceptance is extending to non-elite riders too.
The company is forecasting sales seven times greater than its initial
estimate for Q-Rings, and is planning on outsourcing production for the
first time in the company's history in order to meet the current demand.
Okay, if they're so good…
The claimed benefits of non-round rings are quite compelling: more power
output for equal effort (or conversely, the same power for less effort),
reduced lactic acid production, decreased heart rate, and increased efficiency,
all without adding any appreciable weight. If all of these claims are
true, the obvious question to ask is why even more pros haven't hopped
on board the non-round ring bandwagon.
For one, none of the big component manufacturers have adopted the non-round
ring concept. Shimano even goes so far as to say that its own in-house
research suggests that round rings actually perform better, particularly
in race situations and if the rider already has a good pedal stroke. According
to Shimano's Jasen Thorpe, "The current set of non-round rings adversely
affect cadence since your legs are moving at a non-constant speed. Since
the motion is not constant, there is more energy required to repeatedly
re-accelerate a rider's feet. The differences are subtle, but subtle is
everything at this level." Interestingly, these comments would also
apply to Shimano's own Biopace non-round chainring offerings which the
company quietly dropped in the early 90s after failing to win widespread
acceptance among riders.
Sponsorship among the pro ranks may also prove to be the biggest momentum-stopping
Goliath in the face of the non-round chainring market's David at the upper
echelons of the sport. Invariably, current non-round ring manufacturers
are small companies with relatively tiny marketing and sponsorship budgets
as compared with the big component suppliers. Regardless, Thorpe also
said that Shimano has "no real official position, but the contracts specify
that Shimano equipment will be run. There are still opportunities for
riders/teams to use other equipment, but there should be a clear performance
benefit. Shimano doesn't know all of the answers, but there is also the
element of racer perception. Racers may want stuff that really isn't faster,
but feels faster, and Shimano sometimes can't do much to change that perception."
Moreover, Thorpe said, "Shimano has not gotten requests from any teams
or riders to use non-round rings."
Non-round ring makers offer up a slightly different version. According
to Jean-Louis Talo of O.Symetric, "Shimano is a very big company and it
is hard for a very small company to pay riders to use [its equipment].
There is also lots of pressure from Shimano and Campagnolo, and sometimes
they won't allow sponsored riders to use other rings." Rotor USA's
Howie Cohen shares Talo's sentiments. "Oval ring companies simply don't
have enough money," he said. "Campy and Shimano give pros a
lot of money and gruppos and no one wants to make them angry." In spite
of the difficulties, Cohen reports that the Astana-Wurth team has been
evaluating Rotor's Q-Rings for use in competition (though that squad currently
has rather bigger problems than what chainrings to use).
But are they right for you?
The front shifting problem
Photo ©: Roberto Bettini
Conveniently, the vast majority of us are not sponsored pros and, thus,
have few restrictions on our selection of equipment. The touted benefits
of the new rings are tantalizing, and their use (and success!) by a number
of pros is definitely encouraging.
The last major wave of elliptical chainrings, Shimano's Biopace design,
definitely left behind some fans of the shape, both in Shimano's intended
orientation and in the higher-gear-downstroke set-up used by Rotor and
O.Symetric. Some riders reported more comfortable pedalling with the shape,
and it certainly didn't seem to slow down the top riders who used it,
though there were reports of knee problems caused by the increased gear
at the top of the pedal stroke - the new shapes avoid that problem by
dropping the gear at that point. When Shimano returned to round chainrings
one of the reasons the company gave was that it could not get non-round
rings to shift well with triple chainsets, and that problem persists.
According to his bike sponsor Cervelo, getting Bobby Julich's bikes to
shift gear well is challenging, because a non-round ring continually moves
the chain up and down the front derailleur's shift plates.
Another practical problem is that a non-round shape limits the possible
chainring sizes. Biopace was originally aimed at mountain bike riders,
but the 74mm pitch circle diameter in use for inner rings at the time
meant it was limited to 28 teeth. A round ring on the same PCD could go
down to 24 teeth, and the 17 percent reduction in bottom gear was a no-brainer
that massively outweighed any advantage of the elliptical shape. This
is less of a problem with modern non-round rings as Rotor offers 36/50
rings in a compact road pattern (110mm PCD) and a 24 in a current-standard
94mm MTB pattern.
That just leaves the question, "Will they make you go faster?"
Non-round rings certainly seem to work for Bobby Julich, among others,
and they're not much more expensive than top-quality round rings, making
a trial run one of the cheaper experiments you can do in search of better
performance. We'd be very
interested to hear from Cyclingnews readers who've used the
new generation non-round rings, but from the looks of things, it seems
that this iteration of the idea may have some real staying power.