The adverts in bike magazines try to convince you that their components are more “aero” than somebody elses, the tech time trial geeks in your club are obsessed with “aero”, aero wheels, aero frames, aero handlebars, aero seatpins, aero chainrings, even aero pedals, the list goes on. This is all well & good, aerodynamic kit does make a difference, especially in a time trial, but if you’re concentrating on having the most aerodynamic bike, you’re maybe spending vast sums of money on vanity, rather than first dealing with the real issue, you.
The ‘You’ Issue
A quick study shows that somewhere between 65 to 85% of aerodynamic drag is reported to be caused by the rider, the rest by the bike. The massive 20% variance across riders is caused by many factors. For example, take two riders with the same limb & body lengths, but one carries lots of weight in muscle or fat (or both), while the other is running at ‘pro-level’ body fat. The two riders would therefore fit exactly the same size bike, which has the same drag for both. Where it varies is that the large rider’s forward motion is affected by his size much more than the smaller rider, so of his overall greater drag, his bike’s percentage share is smaller. There is no standard percentage drag apportioned to your bike, it’s different in everybody, it’s even different depending on what clothes you’re wearing. So any figures you see on ‘time saved over 40km’ for any particular component, are based on many assumptions. We can safely assume the marketing information is going to be at the more generous end of possible savings, while not being untrue, only a very small number of people may get this maximum benefit.
Bits n Pieces
This brings us back to component choice (I include the big items like frames in this, but not wheels, see later for that). If you’ve not got your optimum position, or something reasonably close to it, buying all the aero kit in the world may not to help you at all, it may even hinder you. Bad equipment choice, from a ‘fit’ aspect, can lock you into a less than perfect position by not allowing your body to get as aerodynamic as possible. It’s all too common, when I see time trial pictures posted, there is a strange draw to have a look at the bike-cost versus position, quite often it’s incredible that so much is spent without ever going for a proper bike fit or taking good advice.
As a start, a fully adjustable set of aero-bars & an adjustable stem are very cheap options considering the cost you’re intending to spend. That should allow you to set up a position correctly on your current bike, which, may not make your bike look pretty, it may save you a lot of money in the long-term. Then you have the opportunity to know exactly where your saddle & handlebars should be in relation to the bottom bracket, a quick check with a tape & a spirit level on your desired frame (with wheels in) should indicate which size it is you’ll require. Not going along this route may result in you buying what would be your normal road bike size. Often, riders will require a different size, with a longer or shorter top tube, or a lower stack height. You’ll need to get your body to fit this new fast-looking bike without compromising your ideal position, while using available kit. So if you buy one with too short a top tube, you may not find a stem long enough, time trial bike fit is not simply a case of ordering a medium, if you normally ride an off-the-peg medium road frame. It requires a bit more work, you may require something different to what you expected.
The Wheel Question
This is another vastly complicated subject, in this instance it comes under a completely separate topic, as wheel choice has zero impact on position. So you can probably buy your wheels first, use them on the new bike, especially as wheels have a relatively large impact on your speed. But as with other components, there’s no hard & fast rule as to which wheels are best for you. Weather conditions, a rider’s weight & ability to buffer cross winds also come into play here, so trying wheels before you buy could be another valuable piece of testing before you reach for the bank card.
The Gist Of It
Spending some time really looking at your position, or getting somebody with some knowledge to look at it, probably doesn’t give you that instant gratification of buying a shiny new component, or a flash time trial bike. It’s maybe the non-sexy option, maybe it’s difficult, maybe you’ve “not got the time” or maybe you believe the adverts to the letter. The fact is that you could buy ‘the fastest frame in the world’, but if you buy a size you can’t replicate your ideal aero position on, then you’re going to be catching a lot more wind.
The golden rule should be to sort your position first, then (and only then) find the aero frame & components that allow you to replicate that position. This is where buying your new TT frame from a local bike shop really helps, they should be able to let you ride a bike of similar geometry & give some valuable advice on the matter, before you spend your hard-earned cash.
Time trial bikes look great, having one makes people feel ‘a bit Formula 1’, they’re a desirable addition to your stable. But always bear in mind the advantages you get from components are minimal compared to your body position. Be sure you can transfer your highly efficient position across to the geometry of a new time trial frame.
Don’t get carried away by a bit of shiny aerofoil bling, choose the correct bike by spending some time getting your aero set-up dialled in on another bike first.