What's Cool In Road Cycling

PEZ-Tests: Bontrager Aeolus 5.0 Wheels

My defining moment with aero wheels came unexpectedly, quickly, and at surprisingly low speed. It happened at the Amstel Gold cyclosportif ride in April, as I was coasting along chatting to some other riders. It made a believer outta me – both in aero wheels – and these Bontrager Aeolus 5.0 carbon clinchers

The Defining Moment
It’s not often a piece of cycling gear makes such a dramatic difference to my riding that I actually notice it… I’d been riding 50mm deep section aero wheels for a few months, and although the two different brands I was on both felt good, I was always more concerned with the added weight I was carrying than with how much faster I might be riding due to the reduced drag of the rims.

Then I found myself in Holland, riding the Amstel Gold course with 18,000 other riders as part of Velo Classic Tours’ Ardennes Week tour, working it out on the 130km route that took in about 15 of the famous bergs that define this race. The course is always going up or going down, and usually with a wind that, due to the twisty-turny nature of the course, is always changing direction.

Because we were in no hurry to attempt a course record, and the sheer number of riders made hammering almost impossible, there was plenty of opportunity to enjoy the sunshine, the scenery, and the company of the VCT’s other guests.

Riding the courses of the Ardennes classics in April with VeloClassic Tours was a surprisingly good way to really get to know the Aeolus 5.0’s.

And I was doing exactly this… riding beside one of the guests (who outweighed me be at least 30 pounds, and was NOT riding aero wheels – this will make sense in a minute) at an easy pace, maybe 25kmh, and coasting down a slight grade as we talked about the day. Neither of us was pedaling and we rolled along at the same speed.

Then it happened… I started to accelerate past my companion and pulling away – simply by rolling down the hill.

At first I was confused – this never happens to me – being a lightweight at 140lbs, I’m usually the guy who accelerates the slowest on the descents, and has to chase down the bigger guys…

But it happened again. And again. Time after time, all day long, I found myself accelerating faster than other riders who were not using aero wheels.

I quite liked this new found speed, and tested this ‘slow-level’ acceleration several more times over the next few days. Each outcome was the same – I was going faster than riders of all sizes with non-aero wheels.

It took me about a minute to deduce that I was indeed the benefactor of faster wheels – the Bontrager’s were doing what I’d been told they would – and I was witnessing this speed right between my own legs.

A Little Background
The Bontrager Aeolus line started when the call came from Team Discovery Channel a couple years back to develop a carbon aero wheel they could race in all kinds of conditions – not just windless TT’s. The first wheel to appear was the 65mm deep section Aeolus 6.5, and the 5.0 followed a few months later, partly in response to the lighter riders on the team wanting an aero wheel that they could manage even in windy conditions. Tubulars were the first to arrive, with clincher versions not far behind.

The rim itself is made with TREK’s patented OCLV process, to produce a seamless, one piece rim with hooked edges and spoke holes. They’re also the same rim as Bontrager’s super strong XXX-Lite carbon clinchers (read the PEZ-test here). They’re 22mm wide, which Bontrager (and a few other big name wheel makers) has found to be an optimal width to:
• smooth airflow next two a 23mm tire
• reduce pinch flats & optimize ride quality vs a narrower rim
• offer best balance of strength to weight ratio for a road racing rim

These wheels are a collaboration between Bontrager and reknowned wheel-meister Steve Hed whose own wheelworks are nearby the Bontrager facility in Wisconsin. Steve has a long running relationship with the guys at Bontrager, and he’d actually rather work on making a wheel faster than worry about whose name goes on it.

The raw rims are sent to HED’s factory where the HED-designed aero-shaped ‘nose cones’ are attached, and balanced to eliminate uneven weighting. Final wheel build-up is completed back at Bontrager HQ, by hand, using proprietary Swiss DT spokes, and Bontrager designed aero-hubs.

The carbon nose cone, as light as it is, actually adds structural rigidity to the wheel, which allows for a reduction in spokes. The space beneath the fairing is hollow – the OCLV base rim providing nearly all the stiffness needed to build these wheels for only 16 spokes. The Aeolus 5.0 front runs 16 spokes front and rear (vs. 20 and 24 on the XXX-Lite). That’s 12 fewer spokes – which is a nice weight savings any way you weigh it.

• The hills in the Ardennes forest of Belgium and Holland were a perfect testing ground with all kinds of varied terrain and wind conditions – including some super hard climbs like the Mur de Huy and La Redoute seen here. The pros power up these bergs at an alarming rate, but I had to settle for grinding it out as a humbled fan.

The carbon fairing adds some weight to the outer edges of the wheel, which usually affects spin-up speed and acceleration… But never did I feel I was struggling to get these wheels up to speed – and never did I feel like they held me back on climbs – short or long. I chalk it up as more proof to the aero qualities of the rims – allowing the wheels to simply move faster through the air.

Those big holes around the spokes do collect some water, which drains out through another hole drilled in the side of each fairing. I did not ride them in heavy rain, but observed the water did drain out quite easily each time I hosed off the bike.

The stock Aelous 5.0’s come with Bontrager designed hubs built by DT Swiss. Although my test set used only the stock front hub (the rear was fitted with PowerTap’s 2.4 Wireless hub), it performed flawlessly from April through August, and over several thousand kms.

Science Says They’re Faster
Into the windtunnel to test drag, here’s what Bontrager learned. They compared a bunch of wheels to the Aelous 5.0’s, and in the graph below, rank the 5.0’s against an un-named ‘best in class’ competitor.

The green line is the Bontragers, and you can clearly see that it produces less drag (illustrated by the fact that the green line is below the purple line) from a variety of wind angles that range from 0 degrees (straight on) to a 30 degree angle ‘side wind’.

I asked Bontrager’s John Balmer about the testing procedure, and why the graph only shows numbers to +/-30 degrees of wind. He explained that their engineers determined that in real riding and racing conditions, 30 degrees is about the highest angle of effective wind resistance they believe a rider encounters. Wind is basically always changing, and the wind forces on a bike in a peloton are also constantly changing, depending on a rider’s place in the bunch, and the direction and strength of the wind. Add in that the forward motion of the race creates it’s own wind resistance, but also reduces resistance from certain aft angles, and also changes the impact of real wind. There’s a lot more to this that an expert could explain, but that’s the jist.

But based on my actual ride experiences, I don’t need any more convincing. For you skeptics, that fact that were seeing all kinds of aero wheels in the pro bunch these days, regardless of race type, should be enough to convince you aero wheels are a good idea.

• The brake surface is of course carbon as well, and the wheels ship with a set of Bontrager’s special compound cork/rubber brake pads. I’ve been running SRAM Force on the bike and found the braking to very good. The SRAM brake levers tend to be a bit more on-off than some other more gradually modulated designs, but I liked being able to apply plenty of stopping force from both the hoods and the drops. In dry to slightly damp conditions, the pads gripped very well, sometimes too well when I locked the rear wheel up without too much pressure a few times.

The Proof Is In The Ride
So I had to go to Holland to discover how fast these wheels are, but I was right at home when I felt their ride quality. I’ve been running them on a 2005 Bianchi 928, all high-modulous lugged carbon frame – the same one Di Luca won the ’05 ProTour on. I do believe this is the stiffest riding frame I’ve known… that is until I clamped on the Aeolus 5.0’s. These wheels added a suppleness and smoothness to the ride that I didn’t know were possible (and thank God they did!)

Sure, the ride is still racer stiff, but I’m no longer feeling every single millimeter of bump in the road surface. And I’ve ridden these on Belgian cobbles, dirt roads, super smooth tarmac and all points in between – they are a nice riding wheelset.

For me, the extra heft (almost 400 grams for the set) of this 1630 gram wheelset versus my light climbers isn’t noticed on anything more than stop and start conditions or all but the steepest climbs. These just don’t feel as relatively heavy as the scale says they are. Maybe that’s because I am fresher after having a faster wheel on the rest of my ride, maybe they’re stiffer…
what ever the case, I don’t feel like my climbing suffers with these.

In the end the real proof for me was the ride experience I had in Holland. It proved to me these wheels are fast, and also proved to me the Bontrager guys know what they’re doing, and aren’t trying to smoke me when it comes to areo wheels They’ve performed very well over the past 5 months, with no loosened spokes or problems at all. Be sure to check the special story below on my encounter with a wire bucket handle as well – it reinforced my belief in the strength of these wheels.

Priced At US$2999.00 for the set with PowerTap these are not cheap, but then how can you put a price on the thrill of riding faster…?

Price for the clincher set without the Powertap is USD $2249.99 clincher/ $1949.99 tubular.

• For 2008, they’re introducing an Aeolus 5.0 ACC wheel that’s an aluminum rim version of the carbon Aeolus 5.0. Priced at USD $1699.99, and weighing a reported 1660 grams, it brings the Aeolus performance down to a lower price point.

• My test set had a PowerTap 2.4 Wireless rear hub, which we’ll look at in another article – but it’s performed flawlessly over several months and several thousand kms of riding this year – both as a hub, and a power meter.

Get more info at the Bontrager website Bontrager.com

Do NOT Try This At Home: One More Defining Moment
This is a pretty amazing thing – the kind that says something about the strength of these wheels – and also about when might be a good time for me to buy lottery tickets. Sure it’s anecdotal, and there’s no way of telling how much I can truly glean from this about the strength of these wheels, but the outcome made a solid impression on my beliefs of the Aeolus 5.0’s.

Here’s a re-enactment of the carnage using the actual bucket handle in my wheel. I’m convinced it was equal parts good luck – and good wheel building, that saved my skin – and possibly my life.

In late August I was riding with two other guys along a busy section of highway in BC’s interior, doing about 40kph, when my rear wheel picked up a heavy gauge wire bucket handle – the kind you see on 5 gallon pails. I never saw it coming, but at moment of impact, I heard the dreaded and terrifying sound of a chainsaw ripping through the back end of my carbon Bianchi – shredding all in its path – stays, spokes, derailleur, chain… everything.

I braced for the impact that would follow my immediate and impending ejection from the bike… quite possibly into the path of speeding traffic.

The sound of whatever was shredding my bike to bits was horrifying… I was 35 km from home and was about to have a non-rideable bike.

But there are moments in life when things go your way, I often believe for a reason. At this moment, I somehow (miraculously) maintained control and was able to safely slow the bike to a stop.

I feared looking down. Then I saw the pail handle, maybe 16 inches long – threaded through my spokes, thoroughly jammed between the big sprocket and the hub. My fear turned to amazement as I examined the wheel… the spokes were intact – all of ‘em. The tire was fully inflated. Derailleur in place. Everything was fine. Even the wheel was true – hand not budged a millimeter.

It took some reefing to extract said handle, but out it did come… and I was able to complete the ride unhindered by mechanics – (of my bike at least).

The outcome of this story could have been completely different… but on this day luck was mine. Like I said before, there’s no way of knowing how big a part the wheels played in saving my butt, but there’s no denying that I credit a hefty part of the positive outcome to these being on a very solidly built – and strong – wheel.

Note: if you have other experiences with gear, or something to add, drop us a line. We don’t claim to know everything (we just imply it at times). Give us a pat on the back if you like the reviews, or a slap in the head if you feel the need!

PezCycling News and the author ask that you contact the manufacturers before using any products we test here. Only the manufacturer can provide accurate and complete information on proper use and or installation of products as well as any conditional information or product limitations.

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