Aero bike vs aero position — why spending thousands on a new bike might be slower than sticking with your old one

The latest Ostro VAM aero road bike is described by Factor as "unbeatable" . It's certainly a very fast bike, but around 80% of your total drag contribution comes from your body rather than a fancy frame. So, is a modern aero bike enough to offset an un-aerodynamic position? We've been out testing to find out...

If we rewind to just before Christmas, I was very excited when the Ostro VAM arrived at the office. Why was I excited? Well, because it’s been independently tested to be one of the very fastest bikes on the market, and I’m a simple man. I like fast bikes!

Unfortunately, the bike managed to annoy me before I even finished building it, because as I mounted the integrated bar and stem I noticed that it is incredibly - almost ridiculously - wide*. 

> The things I learnt from a professional bike fit that could make you faster

Instead of the 38cm handlebar which I use on my own bike, this particular Factor shipped to us for a review with a 42cm handlebar. And it doesn't stop there... the integrated Black Inc integrated bar also has flare, the result being a measurement of 45cm at its widest point. That's wider than my gravel bike!

* Factor does allow regular customers to spec which width of bars they would like, as well as crank length and stem length, and I've since found out that our reviewer actually asked for the bike with 42cm bars (not for me, but each to their own). In fact, the brand offers more customisation than many of its competitors, which should enable you to get a more aerodynamic position out the box. The observations in this feature are in no way criticisms of Factor or the Ostro VAM itself, we're talking about the effects of body position and equipment choices here.

Another disclaimer: I am not one of those people who thinks we should all be wobbling around on super narrow 32cm bars, but after riding this Factor on my local testing loop I was starting to wonder if this bike was very fast at all. 

It got me wondering:

• Is this a fast bike being ruined by overly wide bars?
• Is the Ostro VAM simply not as fast as Factor says it is?
• Is it fast, but just doesn’t feel it because of the more relaxed position this cockpit puts me in?

The test

> Best road bike handlebars 

To determine the effect of handlebar width and body position on the speed that you can ride at, we decided to put our top-tier modern superbike up against a climbing bike from just over a decade ago.

This is a 2014 Specialized S-Works Tarmac SL4. It doesn’t have a fully integrated front end, a super deep headtube, disc brakes or even the bladed forks; but what it does have is some good old fashioned round profile tube shapes, a set of deep section wheels and, crucially, a slammed stem and 38cm bars, which should put me in a more aero position.

We chose this bike because it represents the pinnacle of performance before aerodynamics and integration took over racing bike frame design. It's also the type of bike that many riders who are currently thinking of modernising to one of these latest aero bikes might currently use.

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The premise is clear then: is a non-aero bike that I doubt even Specialized says will be quicker, be quicker than one of the fastest bikes on the market thanks to one very cost-effective change?

Next, we selected a dry and still day and an 18km flat route that consisted of only left turns so we wouldn't have to slow for traffic. We decided that I'd ride at a constant 260 watts while riding in the drops for the entirety of the efforts. I wore the same clothing throughout the day, and recorded all runs using a set of power meter pedals calibrated each time.

Each bike would get two runs over the 18km course.

Results

What happened? Well, the Factor Ostro VAM went first and completed our 17.8km loop in a time of 30 minutes and 35 seconds. That works out to be an average speed of 34.9kph.

The SL4 went next, completing our test route in a freakishly similar 30:37. That too works out to be 34.9kph (or about 21.7mph for those of you who prefer imperial measurements). 

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It was all down to the second runs then, and the Factor failed to go faster. This time it clocked a time of 30:45, or around 0.2kph slower than it had done earlier in the day. The older SL4 clearly just needed a warm-up, setting the quickest time of the day at 30:31, making it the only bike to crack the 35kph barrier.

If we take an average of these runs, that does mean the SL4 was quicker overall but only by about 6 seconds. This is admittedly less than the margin of error of this test.

Conclusion

Was this whole thing a waste of time then? Well no, I don’t think so. The Factor Ostro VAM is a bike that we know should be quicker, and yet in our real world testing it wasn’t, whichever way you spin the data. While you should always take real world testing results with a pinch of salt, I think that we can conclude that on this course, on this day, a more aero position was faster than a slower position on a more aero bike.   

Since doing this test I’ve been doing plenty of research to see whether the results are consistent with what other people have found, because it does seem wild to think that a decade old, non-integrated, skinny-tubed climbing bike could possibly be faster, or even as fast as one of the latest and greatest all-rounders. 

> How much faster is an expensive road bike?

You see, despite there not being much wind tunnel data for anyone riding at speeds of less than 40kph, we can extrapolate data when they’ve provided CdA values. Of all the tests I’ve looked at, I think that you can expect to save between about five and fifteen watts when riding at 35kph on the flat if you were to upgrade a decent, but not very aerodynamic bike (with deep wheels) to one of these latest, everything-integrated superbikes.  

With said wattage saving, we would have expected to see the Factor being around 15-25 seconds faster on our testing loop, which clearly wasn’t the case.

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So, will going narrower make you faster? In my case, it clearly has, but it’s fair to say that we made a pretty big jump. The Factor measures 45cm at the drops and the Tarmac just 38cm, around 16% less. I’ve looked at all kinds of data for narrower bars making you faster, and while nearly everyone agrees they are faster, it’s up for debate on exactly how much, as everyone is different. For example, you might have wider shoulders than me or stick your elbows out more.

I thought long and hard about how I could hammer home just how important body position is to the speed that you can ride at, and came across this reel from clothing manufacturer Rule28.

 

 

 

 

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A post shared by Rule 28 (@rule28)

Yes, these tests are at 45kph, but we’re not talking about a few watts like there is between the top end road bikes. This is where the biggest gains are to be had, and they might not cost you a penny. We also found during our own day at the wind tunnel way back in 2019 that dropping to a narrower handlebar and tucking your arms and elbows in can lead to very significant savings - a whole 50 watts fewer, in Dave's case, to hold 45km/h. 

Like many amateur cyclists, my local team is full of riders who want to go faster, and many of them believe that the easiest way to do this is to buy a "faster" bike. It's little wonder when manufacturers come out with claims like this:

A 2:21 saving!? Maybe reasonable if Michael Woods had ridden the 183km stage at 42kph solo...but the key bit of information that Factor overlooked here, is that he didn't!

In reality a different bike would never save that much, because he was sat in a group for the majority of the day. If he wasn't, then he wouldn't be travelling at that speed. Us amateurs also ride a lot slower, so we can again expect the difference to be smaller again.

I love aero bikes, but the marketing that surrounds them is often a little over the top. By all means, go and spend money on a fancy new bike (like I have), but if you want to go faster then starting with your body position is going to be more beneficial.

Did you expect these results? Let us know in the comments below.