| I am constantly asked what the big differences are | | | | trumps aerodynamics to a point, so your best position |
| between road bikes and triathlon bikes. The obvious | | | | may not be where you think it is! |
| difference is the fact that one races a triathlon in an | | | | Since the position on the bike and the setup of the bike |
| aero position, but sometimes we see aerobars on | | | | to support that position are the two defining |
| road bikes so what is the real difference? There is a | | | | differences between a road bike and a triathlon bike, |
| smaller difference between uci legal time trial bikes and | | | | what about all the aero tubing on some frames and |
| triathlon bikes, though they look very similar. The short | | | | the round tubes on others? Some frame |
| answer is, road bikes are designed to have three hand | | | | manufacturers advertise how fast their frames are |
| positions, triathlon bikes are designed to have one. Just | | | | based on wind tunnel testing, but I think that is a lot of |
| because a road bike has clip on aerobars, it does not | | | | marketing hype for the most part. Here is a critical fact: |
| imply that it is a purpose built triathlon bike. | | | | The part of the time trial or triathlon bike that creates |
| Draft legal triathlons are the one area where a road | | | | the most drag is the rider! The frame is inside the |
| bike is used with little stub aerobars, but positionally | | | | boundary layer and as such doesn't make as big a |
| speaking, I call them road bikes. They are designed to | | | | contribution to aerodynamics as one might think. |
| be able to do all that a road racing bike does and in | | | | The concept of a boundary layer is a tough one so |
| fact, bicycle racers use the aero position of a draft | | | | imagine the air right next to you going the speed you |
| legal triathletes all the time. | | | | are, and at a certain point away from your body (and |
| Time trial bikes that are uci legal have saddles that are | | | | the bike) the air is undisturbed. There is a "layer" of air |
| set back further than triathlon bikes. The bike is setup | | | | that transitions from no disturbance to actually going |
| so the rider has to actually ride on the nose of the | | | | your speed, as the layer of air molecules that touch |
| saddle (on the rivet, as they say) to get the proper | | | | your skin are doing. The stuff in between is the |
| balance point for the effort being produced. The | | | | "boundary layer." In my industrial design career, I |
| harder one pedals, the farther forward their balance | | | | remember designing a part that went on a boeing 777, |
| point moves. Since a time trialist is racing at max | | | | and I remember learning the boundary layer was 13" |
| effort, the most efficient position is in front of the | | | | thick at the point in question. This means that the 2" |
| comfortable point on the saddle, so riders just tough it | | | | part that was sticking out of the fuselage had virtually |
| out. They don't have to be comfortable and their | | | | no real aerodynamic detriment! |
| events are rarely longer than about an hour so who | | | | What all this means is, a road bike with aero tubing still |
| cares? | | | | won't be as fast as a triathlon bike with round tubing, |
| Triathlon bikes are designed to be ridden for longer | | | | assuming the rider has a good position! What this also |
| distances and at a submaximal pace. This means that | | | | means is, the aerobars, fork and front wheel have a |
| the rider will be putting more weight on the saddle and | | | | huge impact on aerodynamics as they are outside the |
| aerobars because they are not pounding the pedals | | | | boundary layer. Some very fast ironman finishes occur |
| hard enough to support themselves. As such, the | | | | with people riding round tube triathlon bikes, but you |
| saddle and aerobars are located in the place the rider | | | | can bet they are positioned correctly and have good |
| is the most efficient or most aerodynamic. The reason | | | | wheels, aerobars and front fork. |
| I distinguish between the two is traditional triathlon | | | | At the end of the day, there is a lot to a good triathlon |
| positions are very far forward to accommodate a | | | | bike. The first thing, positioning, is the most critical. |
| triathlete's greater hip angle needs and to allow a | | | | Second, great wheels are important. Third, having a |
| super aero position. | | | | good set of integrated aerobars that have the shifters |
| My problem with this position is twofold. First, the | | | | at the ends of the aerobars is important. Next, |
| position is not powerful and many triathletes give up | | | | hydration. Frame bottles or aerobar bottles / hydration |
| more power than is gained by pure aerodynamics. | | | | systems are much better than those behind the |
| Second, the further forward one is positioned relative | | | | saddle. You have to move around to reach back and |
| to their balance point, the more front loading occurs on | | | | get those saddle mounted bottles, so that is an area |
| the knees and overcompensation by quadriceps | | | | that could yield good results. |
| occurs. This muscle imbalance is paid for in the | | | | Triathletes are in charge of all of the aspects for all |
| transition and the start of the run. | | | | three disciplines in the sport. The bike is so critical and |
| The perfect triathlon position is the one where the rider | | | | yet so overlooked it is not surprising that much bad |
| is as strong and aero as possible, with enough comfort | | | | information travels around the transition area. When |
| to be able to stay in the aerobars the entire event. | | | | you are sitting around the cooler after a race, and |
| This is a biggie. If you have to sit up during a race to | | | | someone says that "Brand X" bike won 10 ironman's, |
| rest because the aero position is not sustainable, you | | | | remember, the bike frame didn't win the race. The |
| have a problem. You will be going slower and you will | | | | athlete did, who had the best time in all three legs! |
| be more fatigued in the run. Remember, though, power | | | | |