42
votes
Why aren't road bicycle wheels tiny?
Assuming a bicycle with a conventional rider position, the rider cannot be positioned any lower because there has to be a certain amount of clearance between the cranks and the road. As wheels shrink, ...
- 75.5k
29
votes
Accepted
Why are road bikes (not time trial bikes) used in many triathlons?
The OP linked 4 videos, the first 2 videos were long-course Ironman races, where time trial (TT) bikes were used, while the latter 2 videos were of short-course draft legal races where road bikes ...
- 30.5k
25
votes
Accepted
What is a "gram" of drag?
You're exactly right, drag should be measured in units of force, like Newtons. However, although there are small differences in the gravitational constant across the surface of the Earth, a reasonable ...
- 13.8k
24
votes
Accepted
Aero Bars vs The Drops
Yes, typically you will obtain an improvement in speed by adding clip-on aero bars to your bike.
How much extra speed is dependent on many variables though (mostly how it changes your aerodynamics) ...
- 2,415
20
votes
Accepted
Why aren't road bicycle wheels tiny?
The boundary layer drag (skin friction) is pretty small at large Reynolds numbers and even if still significant, most of it does not happen on the wheels, but also on the frame and on the rider, so ...
- 16.1k
17
votes
What is a "gram" of drag?
How can a gram, a unit of mass, be used to quantify drag, which is a force?
It's a misnomer related to the Kilogram-force (kgf) and its submultiple unit the gram-force (gf), 1 kgf being equal to 1000 ...
- 279
16
votes
What is the drag / power lost to a safety flag?
If the pole is a flexible one, you can do the following:
Choose a windless day
Ride past a second person at a known speed
Let the second person take a picture while you pass
Repeat immediately in the ...
13
votes
Accepted
What position of saddle is best?
Road cycling position is generally a performance position (although not always) and can be viewed as a compromise between three components:
Power - different positions will allow you to output ...
- 30.5k
13
votes
Accepted
What's more aerodynamic on flat bars: backpack or pannier?
A back pack is faster than a single pannier. This exact scenario was tested in the Specialized "Win Tunnel" in their "The Brew Master" episode. They suggested the time savings was 2 minutes over 40 ...
- 30.5k
13
votes
Accepted
At what speed does Aerodynamics of a bike come into play?
As long as you are moving through the air, aerodynamic drag will account for some portion of total drag. Here is a plot that shows the relative contribution of aerodynamic drag vs. rolling drag on ...
- 13.8k
13
votes
Accepted
Is skin or fabric more aero?
The simple answer for professional riders is that clothing is regulated by the UCI. Part 1 Section 3 of the Regulations of the UCI say,
When competing, all riders shall wear a jersey with sleeves and ...
- 13.8k
12
votes
Accepted
Road Bikes: Aero vs. Traditional
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 ...
- 30.5k
12
votes
Accepted
Climbing or aero bike for a light rider?
Generally, being light weight you probably have more of a deficit on the flats, which would point to an aero bike. That is your frontal area per watt per kg will be higher than a larger rider who is ...
- 30.5k
11
votes
Accepted
Riding into a headwind faster than my top speed - how is it possible?
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 ...
- 21.8k
11
votes
Aero Bars vs The Drops
This answer elaborates a bit on the answer above, pulling from some YouTube videos done by Specialized Bicycles in their own wind tunnel as well as a few other sources. It goes on a (hopefully ...
- 29.7k
11
votes
What's the best way to shield a rider from the wind in a group (most aero position in the group)?
When you're in font of the rider that you want to help, then the more aero you are, the less shelter you give.
Riding in a low body position, head tucked and arms narrow makes it easier to ride at ...
- 4,175
11
votes
Wind (nano-/pico-)turbines installed on bicycles for regenerative charging of batteries?
Hilariously, such a product does exist. It comes from notorious crapgadget vendor Thanko. Note that it only purports to charge two AA batteries, and it's not an efficient way to do that. They make no ...
- 29.2k
10
votes
Is going without a helmet more aerodynamic?
I did not do exhaustive literature review, but the first hit, Aerodynamics of ribbed bicycle racing helmets has wind resistance measurements for several different aero helmets with vented helmet and ...
- 21.8k
9
votes
Accepted
Why do track bikes vary between events?
Regarding handlebar selection, aero bars are only allowed in the pursuit (individual and team) and time trial events (1km TT, etc). All the other track events are drop bars only.
Wheel selection is a ...
- 2,055
8
votes
Riding into a headwind faster than my top speed - how is it possible?
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 ...
- 91
8
votes
Accepted
How close do riders follow their wheel/attack
How close do peloton riders typically and strategically follow each other's wheel/attack?
At the higher levels of racing you are often try to tuck your wheel as close as you you can stand, usually ...
- 30.5k
8
votes
Detachable(?) velomobile inspired parts (streamlined/prism)?
If you have a 50 km/h downhill section, that would be a good place to measure. Aero resistance roughly quadruples with speed. Ted Hohls comment below is better formulated. At 50 km/h you can be sure ...
- 121
7
votes
At what speed does Aerodynamics of a bike come into play?
Schwalbe has a great chart from their rolling resistance page on major resistance force for bicycling. Noticeable air drag started from 15km/h and increase exponential after 20km/h.
At 10Mph(16Kmh), ...
- 365
7
votes
Accepted
How can I move the saddle further forward?
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 ...
- 46.1k
7
votes
Can it be estimated when it would actually be beneficial to increase drag in tailwind?
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 ...
- 760
7
votes
Why are road bikes (not time trial bikes) used in many triathlons?
Triathlon and time trial bikes are quite expensive and not wonderful to ride on open courses, hills, and in groups (in other words, general cycling).
So, if you're not so serious about triathlons ...
- 3,494
7
votes
Accepted
Is there any benefit to riders on the front of a paceline?
Yes, it's small but real. Aerodynamic drag in cycling pelotons: New insights by CFD simulation and wind tunnel testing Journal of Wind Engineering and Industrial Aerodynamics
Volume 179, August 2018 ...
- 57.3k
6
votes
What is the average CdA to Weight relationship of a professional Road cyclist?
A very brief answer to part of your question. Perhaps you or others can leverage this to produce a more complete answer, unless Alex or Robert chime in :-)
As you probably know, CdA is the product of ...
- 17.2k
6
votes
Why do deep section front wheels get pushed around in crosswinds?
The answer to your title question is "moving air exerts a force on obstacles", and deep section front wheels have more area affected by side winds so there's more force.
In any crosswind there will ...
- 23.3k
6
votes
Accepted
CdA of a bike without rider
There are, but measurements typically will be protocol-dependent (and vary slightly between different wind tunnels).
For example:
Here is a link to a comparison done at the A2 Wind Tunnel in North ...
- 13.8k
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