# Tag Info

25

No, on the contrary the lead rider also gets a boost. The reason to be unhappy about someone drafting you is that they're too close to be able to react if there's a problem - if you go down they will run over you. The way I understand the boost is that a solo rider is effectively dragging around a volume of low pressure air - you push the air out of the ...

15

To complement Neil Fein's answer, the rider's position is almost entirely controlled (given a particular rider) by the geometry of the bike. Compare the following bikes. In the first image of a hybrid bike, the saddle is slightly below the handlebars. In the second image depicting a road racing bike, the saddle is well above it, forcing the rider to lean ...

13

Obviously the prices seem to support the idea that aerodynamics matter more than a few hundred grams of weight, but at what point does the added weight offset the gain? An exact calculation will depend on the total mass of you and your bike, your speed, the wind, its angle, whether you're climbing, on the flat, or descending, and the speed you're going ...

12

TLDR; assuming my calculations below are correct, there's roughly a 10% increase in air resistance between hot, humid days, and warm, dry days. Add in a slight but imperceptible tailwind or headwind, and it's conceivable that you could experience a 4–5mph difference in cruising speed between two days. Air resistance is the primary force a cyclist must ...

12

The following forces are acting on your bike as you roll downhill (in more or less decreasing order): Gravity The force of gravity is proportional to mass. If two riders have the same aerodynamic profile, the heavier rider will descend with a higher maximum speed. This is easily seen in the formula for terminal velocity. The intuitive explanation is that ...

12

The answer is ... it depends. Normally, by reducing/filling the vacuum that exists behind the lead rider, the drafter would be expected to give the leader a slight boost (though nowhere near the boost the drafter gets). But fluid dynamics is a tricky thing, and there are probably configurations (based on a few millimeters movement one way or the other) ...

11

No. The only reason to get angry at a drafter is if they are not safe or if they don't take their turn. Conservation Law: oversimplification, but in this case if there are no drafters, the extra energy to separate the airflow is just wasted as the turbulence collapses.

11

They are very similar but have to follow different certification rules. For example, under UCI regulations the saddle of a TT bike must be at least 5 cm behind a vertical line drawn through the bottom bracket (cf. Rules 1.3.011 to 1.3.025), there are constraints on the size, shape, and orientation of frame members, and so on. Triathlon bikes are certified ...

11

GC leaders are generally not out in the wind by themselves or taking many pulls on the front. They often put time on the field on climbs and in individual events like TT (which use bikes focused on aerodynamics). As such, in pack riding GC leader will likely favour a bike that focuses on climbing (light and stiff) and handling (note, aero road bikes are ...

9

You can do it, because your bike is connected to the ground. The work done when moving an object is proportional to distance and resistance force (which consists of air resistance and rolling resistance for bikes). The air resistance depends on air speed (ground speed + wind speed), but distance depends only on ground speed. Going slower reduces the energy ...

8

They're heavier, hotter (vents would do the opposite of what you're trying to do with an aero helmet, which is to route air up and over the helmet), and it's more difficult to turn your head (it doesn't completely prohibit turning your head but you lose the benefit of the shape as you turn it off-axis) so you have to depend on peripheral vision more. Plus, ...

8

I recall this thread, and thought I'd add a link to a post describing an impromptu experiment I conducted this week, which tested the impact on the power demand of a test rider (172cm 60kg female on a track pursuit bike riding at a quasi-steady state velocity on an indoor wooden velodrome) of another rider (185cm 80kg male on mass start track bike riding in ...

8

If you are close enough to get into their Slipstream, you can essentially kill their drag. This might feel like a boost because the wind that was previously pulling them back is now transferred to YOUR rear and not sucking on them anymore. Here is a photo of a bullet's slipstream (wake), where you can see the air sucking the bullet backwards. There is no ...

8

What you're referring to is tucking, an act that's most easily done with drop bars - the curved handlebars with multiple hand positions you see on road bikes. The holy grail for some hardcore roadies (road cyclists) is the flat back, where the rider is tucked all the way forward, their hands on the lower part of the drop bars - the "drops". This is done so ...

8

You can do this because of the gearing of the bike. When you're riding at a slower ground speed, if you shift to a lower gear to keep your pedal RPM the same, then the same force on the pedals produces a higher thrust at the tire. Even if you do not shift, it is easier to produce higher force on the pedals at lower RPM. The strength of a cyclist is ...

7

You've exceeded the manufacturer's recommendation on saddle positioning -- the clamp is supposed to clamp on the saddle between the stop lines. So, the saddle should be moved back. Many people exceed these recommendations, but its at your own risk. I'd be less inclined to do it on a lightweight or fancy saddle. The easiest way to move the saddle forward is ...

7

A tailwind reduces your relative airspeed and therefor the drag you generate. You can go faster relative to the ground with the same power output. The only time increasing your profile might be beneficial is if the wind is traveling faster than you are, relative to the ground .... Unless you cycle slowly or the wind is very fast, it's usually not the case. ...

6

Aero frames are generally slightly heavier than the standard frame you'd compare it to, though the difference might not even be enough for the average person to notice. Someone who regularly competes in time trials might want the increased speed on relatively flat ground, competitors will certainly notice the difference. If you're not competing in time ...

6

All the helmets in the picture are aero helmets, just different styles. Helmet needs in sprint competitions are different than for individual timed events as the rider is more likely to turn their head around to assess the race situation as well as be in various positions on the bike (e.g. out of the saddle while accelerating) which means the interaction of ...

6

The aero benefits of deep rims come from reducing the spoke length. Imagine that you're drafting behind a large truck at 25 MPH; you're not experiencing any headwind, but your spokes are still going around in a circle and slicing through the air. So reducing the total length of all the spokes (by using less spokes or shorter spokes) will give you better ...

5

I think this is kind of a non-question. You want the helmet that rides the fastest? For anything "fastest", either components or kit, just look at what the professional riders are using. This seems to imply that you either wear a regular-design lid (albeit one which is very light, very ventilated, and probably very expensive). Or, you go for a time-trial ...

5

If there is an aerodynamic difference, it is so small it is utterly unnoticeable in practice. In a paceline, the resistance experienced by the front rider is overwhelmingly dominated by slicing through the air in front of him. Perhaps you're thinking of a velodrome race? What often happens is that the second rider will pass around the outside by quickly ...

5

Except for the steepest of hill climbs, aero wheels will almost always improve speed; however, the choice among race wheels will depend on the types of races you do, your strengths as a racer, how important small improvements in aerodynamic drag are to your goals, and the size of your bank account. For short individual time trials, .0025 m^2 savings in CdA (...

5

Looking at your times, your times on the bike leg are below the levels you are setting in the other legs. But given that you are barely training for the bike leg, your times are pretty good. This site says How long does it take to finish a Half Ironman Triathlon? The answer, based on our analysis of more than 67,000 finishers in 40 Half Ironman ...

4

I think it depends on the course you're riding. Professionals will have multiple wheelsets and use different wheels depending on the course they are riding for the day. Weight really only makes a big difference if you are climbing or accelerating. So for a course with a lot of climibing, where aerodynamic drag is at a minimum anyway, they will often ...

4

On high humidity days, the air has less mass due to the more H2O, which is lighter than typical O2, CO2 and N2 weights. On high pressure days there is more mass for you to push aside. Air temperature also plays a part - hot air is less dense than cold air. Therefore a hot, low pressure, high humidity day requires less mass to be pushed aside. These make a ...

4

Thought I might add some extra comments to those very good and comprehensive examples of the aero v weight scenarios that Robert provided last year. In particular the dynamic scenario of accelerations on flat terrain, which is a little more complex than steady state cycling. Some might think light wheels would accelerate better than heavier aero wheels, ...

4

You likely need a bike fit. The body position for using aero should be quite different than riding on hoods. Unfortunately, there really isn't a good compromise between a road and a TT/aero position. I recommend getting a professional bike fit. I'm including the "quick fit" below, but there are too many factors in play and millimeters matter. If possible, ...

4

You get aero benefit when you ride at the front and at the back. So it depends on how big is the group. Or more to the point, how long you spend time at the front and at the back. If you ride in two lines in group of four the you get the aero benefit 100% of the time (in different amount). If there are 6 in a group riding in two lines then 67% of the time ...

4

Aerodynamics of a helmet cannot be considered in isolation but rather how it affects aerodynamics when on the rider. The fastest helmet choice for one rider won't necessarily be the fastest for another, it's quite an individual thing. I've done many, many aero tests of helmets on rider, and am often surprised at the combination that proves best. In general ...

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