Nov
teden in nov namig, tako da pozdravljeni dragi bralci in bralke.
Namigi kar dežujejo z izjemo velikonočnega ponedeljka. Danes se
obračamo na cesto, na kolo ali pa tudi na avte. A ker je to blog, ki
se vrti na bolj kot ne telesni pogon, se bom dotaknil cestnih koles.
Gorskih koles tukaj ni omenjati, morda kar se tiče teže. Danes bo
govora o večni tekmi med aerodinamiko proti teži.
Preden
so cestna kolesa postala popularna so bili le najbolj zanesenjaki
mahnjeni na jeklena kolesa, ki so bila težka in okorna. V
devetdesetih letih prejšnjega stoletja še ni bilo veliko govora o
karbonu in aerodinamiki. No, v tekmovalnem kolesarstvu da, a za
navadne smrtnike pač ne. Kdo je hotel imeti lažje kolo, je
preprosto zvrtal luknje v okvir ali komponente. To se seveda ne dela
več.
Vrnimo
se v preteklost, v leto 1989, ko je Greg LeMond s svojim, za takrat
vesoljskim aerodinamičnim kolesom pometel s konkurenco v kronometru
in seveda zmagal na Tour de France. Od takrat naprej se inženirji
trudijo v tej smeri.
Ne
pozabimo pa seveda omejitev, ki jih je UCI uvedel glede teže koles
leta 2000. Najlažje kolo sme biti težko 6.8 kg. Če je kolo lažje
od tega, mora biti kolo obteženo z utežmi. To velja za tekmovalno
kolesarstvo. Inženirji različnih proizvajalcev se neumorno trudijo
narediti kolesa čim lažja, a ponavadi na ceno materiala in na
žalost varnosti. Po pravici povedano, se ne upam usesti na kolo
lažje od 4 kg in se peljati po naših cestah.
Sem
že izgubil rdečo nit. Skoraj da. Najprej sem hotel samo navesti
nekaj dejstev in morda razsvetliti nepoznavalce.
Skratka,
sedaj smo v telu 2018, ki je v ozadju tehnologija še kako velika. Če
damo tekmovalno kolesarstvo na stran, saj pač je tekmovalcev veliko
manj kot rekreativcev. Prvo vprašanje je; kako narediti kolo lažje?
Preprost odgovor je; debelina denarnice. Lažji materiali kot so
karbon in titan pač niso poceni. Drugo vprašanje; kako narediti
kolo bolj aerodinamično? Odgovor je; z aerodinamičnimi
komponentami. Dodajanje aerodinamičnih komponent je malce ceneje kot
zamenjevati z lažjimi. Dodatki kot so triatlonski nastavek krmila,
aerodinamični obroči ali nastavki za okvir so cenejši.
 |
Lightweight kolo. Eno najlažjih na svetu. |
Ampak,
če bom lažji bom šel hitreje v hrib. Seveda, da boš šel. Najprej
se vprašaj, po kakšnem terenu kolesariš; ali je bolj hribovito ali
bolj ravno. Morda si že kdaj opazil, da do hitrosti cca. 25 km/h ni
težko priti. Naprej pa malo težje. Za vse to je kriv nevidni
sovražnik, ki se mu reče zračni upor. Prokleti k****. Ko
kolesarimo hitreje od 25 km/h, porabimo približno 90 % energije,
samo da se prebijemo skozi tega nevidnega sovražnika. Se je za
vprašati, koliko watov obračajo profesionalni kolesarji na
kronometru. Še to, v 5 % klanec je še zmeraj boljše aerodinamično
kolo kakor lažje, saj v tak klanec še zmeraj premagujemo zračni
upor kot pa gravitacijo.
 |
Aerodinamično kolo. Ni kronometrska specilaka. |
Lažje
kolo bo šlo hitreje v klanec. No, kolo samo ne. Tudi kolesar pač ne
sem izgledati kot reklama za michelin pnevmatike. Najprej je treba
kakšno kilo na sebi izgubiti. Kar se pa samega kolesa tiče, pa je
pomembna tudi razporeditev teže. Če imamo dva para platišč, oba
težka 1,5 kg na par. Ene so z lahkimi karbonskimi naperami,
keramičnimi ležaji in jeklenimi obroči, druge pa so z
aluminijastimi naperami, jeklenimi ležaji in karbonskim obročem.
Prve so težje na obodu, druga pa na sredini. Se pozna vse to, ko je
treba poganjati v klanec. Pri vseh ostalih komponentah se pa to na
srečo ne pozna. A vsak lažji del je seveda dražji. Vijaki in
matice iz titana, karbonska krmila in držala nanesejo ceno.
Aerodinamično
kolo bo šlo hitreje po ravnini. Ne pravim, da je potrebno imeti
kronometrsko "kozo", pač pa če imamo triatlonske nastavke
za krmilo, obroče z višjim robom ter oprijeta oblačila, se bo
zmanjšal zračni upor in bo za isto hitrost porabljeno manj moči.
Vsi nastavki, za povečanje aerodinamičnosti so malce cenejši, ker
tu teža ne igra prevelike vloge. Tudi sama teža kolesarja igra
manjšo vlogo kot za v klanec. Ko pogledamo profesionalne kolesarje,
ko imajo zadnji obroč poln, jim to pomaga ustvariti vrtilni moment.
Sedaj
pa odgovor na vprašanje: ali aerodinamično ali lažje kolo? Ne vem
odgovora, saj je to odvisno od vsakega posameznika.
To
je to, za današnji namig. Če se odločaš med temi dvema vrstama,
upam, da sem ti malo pomagal. Na kon
Do
naslednjič.
.....................
New
week and new clue, so hello dears readers. On the exception of easter
monday the clues just keep coming in. Today we keep focus on the
road, on the bikes and also on the cars. But this is a blog for
physically activity, i'll be focusing on road bikes. MTB bikes will
not be mentioned here. Today i'll discus the ongoing battle between
aerodynamics versus lightweight.
Before
the road bikes become popular, there were just a few enthusiast open
for steel bikes which was heavy and cumbersome. In the 90's in the
past century there wasn't much to talk about carbon fibers and
aerodynamics. Well, maybe in profesional cycling, but not among
the amaters. Wjo wants to had a lighter bike, he simply drilled a
holes in the frame or components. This is not a practice enymore.
Lets
go back in to the past, in the year 1989 when Greg LeMond, on his
futuristic looking bike won the time trial and won the Tour de
France. Engeneers have their effort in that direction.
Don't
forget about UCI regulations from the year 2000 fo the minimal weight
of the bike. The lightes bike in PRO Tour can be 6,8 kg. If the bike
is lighter, a special weight are putted on. That regulations are for
profesional cycling. Engeneers of diferent manufacturers are trying
their best, to make a lightest bike possible, usualy on the price of
material and saddly the safety. To tell you the truth, i will be
scared to sit on a 4 kg bike and ride on our roads.
Did
i loose the focus? Almost. I just want to let you know some facts and
brighten those who don't know it.
Today,
we are in year of 2018, where technology behind all that is great. If
we put proffesionall cycling aside, because the proffesionall cyclist
are less in number then amaters. First question: how to make a bike
lighter? Simple answer is: the thickness of your wallet. Zhe lighter
the material, like carbon fibers and titan don't come cheep. Second
question: how to make a bike more aerodynamicall? Answer is: with a
aerodynamicall components. Adding aerodynamicall components is easier
and cheaper then light weight materials. Accessories like clip on
handlebar, aero wheels or accessories fro the frame are cheaper.
 |
Lightweight bike. One of the lightest in the world |
But
if i'm lighter, i'll be going much faster uphill. Of course you will
go. But ask yourself, on what kind of terrain are you cycling: is
more hillier or flat. Maybe you alredy notice that to speed about 25
km/h is not a problem to come. But faster is a little bit harder. The
main reason for that is an invissible enemy called air resistance.
Dam you. When we cycle faster than 25 km/h we spend about 90 % of our
energy just to move this invisible enemy. I'm wondering, how many
watts are rolling among the proffesionall cyclist in time trail. And
one more thing, in 5 % grade uphill, the aerodynamical bike is faster
than lightweight, because in that kind of hill, we still move air
resistance than gravity.
 |
Aerodynamicall bike. Not a time trial bike. |
The
lighter the bike, the faster it will go uphill. Well, just a bike
alone it woudn't. The biker itself can't look like figure for
michelin tires. First loose a pound or two. What is for the bike, the
weight distribution is important. If we have a two sets of wheel,
both weight a 1,5 kg per set. First one has a light carbon spokes,
ceramical bearings, and steel ring, second has a aluminium spokes,
steel bearings and karbon ring. First one are heavier on the outside,
second in the center. A the other components the weight distriburion
is not that issue. But every lighter part is more expensive. Nuts and
blots from titanium, carbon handlebars and stems add up the price
Aerodynamicall
bike will go faster on the flat terrain. I don't say that you need a
time trail bike, but if you put on clip on bar, wheels with a higher
edge and fitted chlotes, the drag will be reduced and for the same
speed, you will use less amount of energy. All components for
aerodynamicall efficiency are cheaper, because the weight is not that
kind of issue here. Aslo the weight of a rider is less important that
for uphill. When we look the proffesionall cyclist that they have
disc back wheel, that gives them angular momentum.
And
now the answer for the question: or aerodynamicall or lightweight? I
don't know the answer. That is up to you.
This
is it for todays clue. If you are tilting between this two options, i
hope that i was helpfull.
'till
next time.