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