ponedeljek, 23. april 2018

Namig no. 11








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.