Shadowing Practice: How Tire Rolling Resistance Affects Cycling Speed ? - Learn English Speaking with Video

Les maken...
1
What is rolling resistance and why should you think about it on the bike?
2
Rolling resistance is, quite simply, the energy that is lost as a tyre rolls along a surface.
3
The energy is mostly lost because of the constant deformation of that tyre against the surface.
4
Now, whilst paying attention to rolling resistance is important, it's not actually the biggest resistance factor when it comes to cycling fast.
5
Air resistance rises in a squared ratio with increased speed.
6
At a speed of 20 kilometers an hour on a level ground, air resistance has already become the main resistance force.
7
And the faster you go, the more air resistance increases exponentially.
8
So before even thinking about rolling resistance, get aero.
9
Acceleration energy is also expended, for instance, the weight of the wheels is of great importance when this mass has to be brought up to rotation.
10
Then when riding uphill, the main resistance force to be overcome is the gradient resistance.
11
This is basically the additional resistance added by fighting gravity.
12
And in addition to these, there are other friction resistances in the chain, the bottom bracket, and other rotating parts.
13
Now, in a well-serviced bicycle, these represent a very minor part of the total resistance.
14
So, should you just ignore rolling resistance then?
15
Well, no. Because improving your rolling resistance may be the cheapest
16
and easiest upgrade you can make to your bike to go faster.
17
You can improve all the others by getting aero, by getting a good bike fit and spending the time getting used to it, by getting aerodynamic and light frame,
18
by getting some aerodynamic race wheels, and even by upgrading the bearings to maybe ceramic bearings.
19
But you can get big gains simply by upgrading your tires and improving your rolling resistance.
20
And of course, pumping those tires to the right pressure.
21
It's pretty simple.
22
A tire with a higher rolling resistance will require more power
23
to attain the same speed than a tire with a lower rolling resistance, will require less power.
24
So what factors affect the tyres rolling resistance?
25
Tyre pressure.
26
On a completely smooth surface the following applies.
27
The higher the inflation pressure the less the tyre deforms and thus the lower the rolling resistance.
28
However on an imperfect surface which we are always riding on lower inflation pressures cause the opposite, lower rolling resistance.
29
Imperfections in the road on a very hard tyre will cause bouncing and skipping and increased resistance, not to mention the toll that takes on the rider in terms of fatigue.
30
Whereas a tyre with low inflation pressure can adapt better to the rugged surface.
31
It sinks into the ground less and absorbs imperfections rather than pushing against them and bouncing off them.
32
And so with a softer tyre the whole rotational mass is held back much less on the uneven surface.
33
Tire width.
34
At the same tyre pressure on a smooth surface a wider tyre will have lower rolling resistance than a narrower tyre.
35
This is essentially because a wider tyre with the same pressure actually has an effect of higher pressure
36
because a wider tyre with a higher air volume will have a higher casing tension.
37
Basically the wider tyre will be harder because it needs more air to fill it and the contact patch, the bit of the tire touching the road, will be smaller and wider, decreasing the rolling resistance.
38
But again this only holds true on a smooth surface.
39
On an imperfect surface with the pressure corrected for the width to get the tire to the right hardness, the contact patch on the road for a wider tire will be shorter and wider than a narrow tire,
40
decreasing the rolling resistance.
41
Importantly the wider the tyre will have more versatility and the range of pressures you can actually use, allowing you to more easily correct for the roughness of the surface.
42
Tyre construction.
43
Obviously the tyre construction has an effect on rolling resistance.
44
By using less material, less material can and will be deformed.
45
And the more flexible the material is, such as the rubber compound, the less energy is lost through deformation.
46
Generally, smoother treads have a lower rolling resistance than rougher treads
47
and that is why almost all road
48
and triathlon racing tires have very smooth tread patterns
49
if any tread pattern at all interestingly actually in racing tires for the road the tread pattern
50
that is there is actually not there for grip
51
or water dispersion it's mostly there for aerodynamics
52
because the tread pattern actually trips the laminar flow as
53
that of that air that's hitting the tire to improve the aerodynamics So,
54
should you consult a website like BicycleRollingResistance.com where they list all the tested rolling resistance of all tyres
55
and simply choose the one from the top of the list?
56
Well, yes and no. Yes, the tires on the top of that list will be the fastest.
57
However, they're always compromises.
58
Some of them may sacrifice durability for that extra speed and be more prone to punctures.
59
Some of them may have a different compound that sacrifices comfort
60
and grip and road feel and some may simply not work well with your wheel and bike setup.
61
It's also worth pointing out that the difference between the top of
62
that list of racing tires and the middle of
63
that list of racing tires is about a two to three watt saving
64
which is an almost imperceptible difference for most mere mortals.
65
They will however have a significant difference in those racing tires over your standard training tires.
66
So the answer is that the best tire for you depends on many factors
67
but it is worth considering investing the $100 to $200 in a good pair of racing tyres.
68
It may just be the cheapest watts you buy this season.
69
One more thing before we go, you may be asking which is faster rolling resistance-wise, tubeless or clincher?
70
Well, the speed of a tyre actually depends on its construction and not whether it's set up clincher or tubeless.
71
So, a slow tubeless tyre will actually be slower than a fast clincher tyre.
72
However, generally speaking, setup does have better rolling resistance than a tube setup.
73
However, if you put a latex tube in a clincher, the rolling resistance is actually the same as tubeless.
74
I hope you've enjoyed this video.
75
Happy riding!

Woordenschat en spreektips bij deze les

Deze video bevat 75 zinnen en 1065 woorden om na te spreken. Het gesproken deel duurt 5:59. De spreker praat in een natuurlijk tempo van ongeveer 178 woorden per minuut, dicht bij een alledaags gesprek. Slechts 76% van de woorden hoort bij de 3.000 meest gebruikte Engelse woorden, dus de woordenschat is pittig.

Belangrijke woorden in deze video

15 woorden uit de video die het leren waard zijn, met uitspraak en betekenis:

WoordUitspraakBetekenis
tyre zelfstandig naamwoord/taɪə(ɹ)/band
tire werkwoord/ˈtaɪ̯ɚ/vermoeien
tread werkwoord/tɹɛd/stampen, vertrappen
smooth bijvoeglijk naamwoord/smuːð/vlot
inflation zelfstandig naamwoord/ɪnˈfleɪ.ʃən/inflatie
narrow bijvoeglijk naamwoord/ˈnæɹəʊ/nauw, smal
tube zelfstandig naamwoord/tuːb/tube
sacrifice zelfstandig naamwoord/ˈsæk.ɹɪ.faɪs/opoffering
bearing zelfstandig naamwoord/ˈbɛɹɪŋ/lager
depend werkwoord/dɪˈpɛnd/afhangen
patch zelfstandig naamwoord/pæt͡ʃ/lap
compound zelfstandig naamwoord/ˈkɑmpaʊnd/verbinding
decrease werkwoord/dɪˈkɹiːs/afnemen, verminderen
grip zelfstandig naamwoord/ˈɡɹɪp/greep, grip
bounce werkwoord/baʊns/stuiteren, ketsen

Phrasal verbs die je zult horen

WoordUitspraakBetekenis
point out werkwoordaanwijzen, aanduiden
set up werkwoord/ˌsɛt ˈʌp/bereiden, voorbereiden

Uitspraak om op te letten

  • De “th”-klanken: smooth /smuːð/, width /ˈwɪtθ/, triathlon /tɹaɪˈæθˌlɑn/
  • De klanken “sh” en “zh”: inflation /ɪnˈfleɪ.ʃən/, essentially /ɪˈsɛnʃəli/, ratio /ˈɹeɪ.ʃoʊ/, tension /ˈtɛnʃən/, rotation /ɹoʊˈteɪʃən/
  • Lange woorden — let op de klemtoon: essentially /ɪˈsɛnʃəli/, importantly /ɪmˈpɔɹ.tənt.li/, acceleration /əkˌsɛl.əˈɹeɪ.ʃən/, aerodynamic /ˌɛəɹəʊdaɪˈnæmɪk/, deformation /ˌdɛfəˈmeɪʃən/

Zo oefen je met deze video

  1. Luister de hele video één keer zonder te spreken en noteer de woorden die je niet kent.
  2. Begin op 0,75× snelheid, spreek zin voor zin na en ga terug naar normale snelheid zodra het makkelijk gaat.
  3. Neem jezelf op en vergelijk met het origineel; let daarbij op woorden als tyre, tire, tread.

Grammatica in deze video

De structuren die de spreker het meest gebruikt, met de exacte woorden uit de video:

StructuurIn de video
Lijdende vorm be + voltooid deelwoord — het gaat om wat er gebeurt, niet om wie het doetis lost · is also expended · be overcome
Present perfect have/has + voltooid deelwoord — iets uit het verleden dat nu nog telthas already become · you've enjoyed

Wat is de Shadowing-techniek?

Shadowing is een wetenschappelijk onderbouwde taalleermethode die oorspronkelijk is ontwikkeld voor professionele tolkentraining en gepopulariseerd door polyglot Dr. Alexander Arguelles. De methode is eenvoudig maar krachtig: je luistert naar native Engelse audio en herhaalt het onmiddellijk hardop — als een schaduw die de spreker volgt met slechts 1–2 seconden vertraging. In tegenstelling tot passief luisteren of grammaticadrills, dwingt shadowing je hersenen en mondspieren om echte spraakpatronen tegelijkertijd te verwerken en te reproduceren. Onderzoek toont aan dat het de uitspraaknauwkeurigheid, intonatie, ritme, verbonden spraak, luisterbegrip en spreekvaardigheid aanzienlijk verbetert — waardoor het een van de meest effectieve methoden is voor IELTS Speaking-voorbereiding en echte Engelse communicatie.

Shadowing-techniek: lees de volledige stap-voor-stap-gids →