Roadbike or Tribike?

For those who are venturing into multi-sports and still don't have a bike to race with, the question of whether to use a roadbike or tribike ( short for triathlon bike ) is a reasonable question. We always see the pros riding that blazingly fast looking bike, with bar-end shifters and brake levers, tucked down in an aero position in all Ironman races. Do you really need something like that?

I have raced triathlons and duathlons both in a road bike and a tribike, and have experienced what it feels like running after dismounting from both and can tell you this: There's a reason why its called a tribike!

Below is an image of a tribike with the seat angle highlighted in red. Let us decipher what this diagram means:

1. The Seat Angle

The seat angle differentiates the tribike from the road bike. Tribikes have steeper seat angles ( 76-78 degrees ) than road bikes primarily due to the benefit it gives the legs after dismounting and getting ready for the run. Tribikes are designed for a rider to have fresher legs for the run after dismounting from his bike, it preserves his hamstrings which are used when running.

So how does that happen?

Compared to a road bike with shallower seat angles, tribikes enable the athlete to ride "taller" by putting him on a more forward seating position, thereby forcing him to use his quadriceps instead of his hamstrings. This position helps an athlete to cycle easier, with lighter pedaling and almost like in a running position.

To experience how this feels, mount your bike, put your body nearer the handlebars and try pedaling. Next, slack up on the saddle by pushing your butt back, seating on the rearmost part of the saddle. You should feel the pressure on your legs more when in the slacked up position. This is also the reason why you cannot just install an aerobar and basebar on your roadbike, the geometry just won't match the cockpit!

2. The Head Tube Angle

The headtube is the part of the bike where the fork is inserted and where the headset stand on. In tribikes and roadbikes, the angle of the head tube is almost similar, with the tribike's angle just a teeny weeny bit steeper.

However, if you factor in the seat tube angle with the head tube angle, the difference between the tribike and roadbike starts to show. With the tribike's seat angle steeper, the top tube becomes shorter than a roadbike. Road bikes have seat angles of 72-73 degrees which is almost parallel to the head tube. With the tribike's seat tube at 76-78 degrees, its top tube will be around 1.5 to 3 cm shorter. Do the math.

3. The Top Tube

The top tube of the bike is where the head tube meets the seat tube. Its the topmost part of the bike which is located between your legs.

Tribikes are designed to have a shorter top tube than road bikes as the intention is to keep the rider in an aero position, the back curled up like a ball, head down into the wind. Comparing the sizes, a medium tribike would have a top tube of between 53-54 cm while a roadbike will have 55-55.5 cm. Most athletes will tell you that if you're riding a Large sized roadbike, you should be getting a medium sized tribike...NOT!

Tribike manufacturers have already incorporated the measurements into the design of tribikes. So if you are using a Large roadbike, get a Large tribike. Their measurements are different.

I made the mistake of buying a medium tribike when I ride a Large roadbike. I followed the advices of some friends and ended up spending unnecessarily. I changed my stem to 110mm from 90mm and set back the saddle. In the end, I was riding in a roadbike geometry already. The benefit I should have been getting from having a tribike was lost. I was virtually riding in 73 degrees when I should have been at 76 degrees. To top that, I always slid forward when in the aero position and would always have neck and shoulder pains after a ride. The medium tribike's top tube was shorter than what I needed.

The longer stem also made my bike more difficult to maneuver on road rides, plus I had to pull the seatpost up more than regular just to accomodate the correct angle of my legs when pedaling. There were more things to tweak than if I got a Large sized frame at the start.

Some would advise a new multi-sport athlete to buy a road bike, slap on a clip-on aero bar and insert a fast forward seatpost to mimic a tribike geometry. This could work. However, it will not look as aesthetically mean as having a real tribike. Would you like to go through all the trouble of changing seatposts everytime you race? If yes, then go for this set-up, there's nothing wrong with it. But if your intention in getting into cycling is to compete in triathlons and duathlons, why not train and race with the proper equipment?

Being on an aerobar takes some getting used to. You are more prone to crashing while on an aerobar than on a dropbar. Taking this risk, though, is properly compensated with the faster time you will be doing.

It is necessary for someone who gets into multi-sports to think about what's best to ride in races as the bike leg is always 50% of the race already. Back in Camsur Ironman 70.3 2009, I was among the last to come off the water. By the time I was on my last quarter of the bike portion ,I passed almost a hundred athletes already. I was comfortable with my ride because of the correct bike I chose to use. Being on an aero position for more than 2 hours enabled me to catch the faster swimmers during the race. They were using roadbikes which were heavier on the legs, and at the halfway point of their bike rides, they slowed down substantially enabling me to catch them one by one. I also had good legs when I dismounted, and was able to complete the first 10K of the run in just a little over an hour, until I succumbed to the heat.

Going back to the question on whether to invest on a tribike or roadbike, I'd say invest on a tribike if you're seriously doing multi-sports. It will be more costly for you to buy a roadbike now then change to a tribike later. You can use both in road rides anyway, but a tribike will give you better results in races.

Deo P.