Ask a Mechanic: Converting a Road Bike to a TT Bike

I’ve been racing for a while now and am looking to try a few TTs, but I’m not quite ready to commit to buying a whole new TT bike. Any tips on converting my road bike to a TT setup?

Converting your road bike to a TT bike is a cost effective way to get into stage racing or triathlons without purchasing a dedicated bike, but there are quite a few things to consider. While making the bike look ready for a TT or triathlon is simple, ensuring your comfort and safety on the bike requires attention.

The goal of a TT/triathlon bike is to increase aerodynamic advantage. Adding aero extensions to your handlebars and using a more aerodynamic wheel set are the easiest and most effective ways to achieve this. Shortening the bike’s cockpit will make finding a comfortable aero position easier, and since you can’t shorten the top tube, installing a shorter stem and moving the saddle forward are your options. If you don’t have a round seat post, which can often be turned around to eliminate or reverse setback, you may have to purchase a post with less setback than your current one.

Options abound when it comes to adding a set of aero bars. These include anything from a complete base bar with extensions, or just clip-on extensions. Installing a full base bar and extension set up is an involved process, requiring an additional set of bar end shifters for the extensions and brake levers for the base bar. Making this change will also require you to re-cable the entire bike as well. This option is not a fast and easy fix to be done the night before your race, so I recommend choosing clip-on extensions to start with.

There are many different types or extensions to choose from, and you must make sure you choose extensions that your current road bars are compatible with. This is imperative with carbon bars or bars that have a flat top. Clip-ons attach to the bars with a clamp that holds arm support pads and the extension bars. All you have to do to install them is tighten the clamps to the bar and torque the bolts to the manufacturer’s spec. If the torque spec is different between the handlebar and the extensions, use the torque spec from the handlebar. Most extensions allow you to adjust their effective length by either moving the extension bar, the pads, or both, which is key for finding a comfortable aero position. Consider getting a professional bike fit with your new components, since the ideal aero position is very different than your usual road position.

Aerodynamic wheels have the greatest impact on increasing your speed. Swapping wheels is also the easiest way to get your bike ready for a TT or triathlon, but can be the most expensive. Luckily, you can always use your wheels on a new bike when you make the leap to full-time bike racer. Lighter wheels will provide faster accelerations and higher speeds, as will deep cross-sectioned “aero” wheels. In fact, aerodynamics are more important than weight in speeds above 18 MPH. Most dedicated TT bikes will run a full disc wheel in the rear and an aero front wheel as well. The depth of the front wheel will often be determined by the conditions. Adding depth to the front wheel increases aerodynamic advantage, but also makes handling the bike harder in crosswinds. The deeper the wheel, the more the wind will push the wheel sideways in a crosswind. For that reason it’s better to run a deeper wheel in the rear, because most of your weight is on top of it and it doesn’t turn side to side.

The last thing to consider when making this conversion actually has nothing to do with the bike. An aero helmet is the most cost-effective upgrade you can make.