This hack is so simple and obvious I almost wanted to leave it out.
But if you’re able to save nearly 10 minutes on a full Ironman, we can’t ignore this one.
A disc wheel is more aerodynamic than any other, so it will make you faster, all things being equal.
Of course, this time benefit will be magnified over longer distances, so if you’re doing a full Ironman, seriously consider getting a disc.
They can be expensive, but there are low-cost options available. For example, you could borrow one (I’ve lent mine out before), or you can go for wheel covers (not true discs but basically the same benefit).
However, if the course is going to be super windy or hilly, you may be better of without the disc.
One really cool way to determine this is www.bestbikesplit.com. Configure your setup in that site and switch out your rear wheel for a disc, and based on its weight and aero benefit the site will tell you how much faster you’ll be.
It’ll take into account the hills, wind, weather and more.
However, you may have to pay for a BestBikeSplit subscription to add multiple bikes and setups to the system.
In fact, this is tip #27, Use BestBikeSplit.
I use a disc from Wheelscience, and on their site here, they show that their disc can save nearly 9 minutes on a full, when paired with an 80 mm front wheel.
Is it worth 8-9 minutes to you over that distance? Or is it worth 4 minutes to you in a half? Or almost two minutes in an Olympic distance?
The last piece of advice I’d give before investing in a disc is to ensure you have your basics sorted out first: A proper bike fit, aero clothing, and of course getting your power right (IF and VI).