{"id":356,"date":"2026-09-17T07:16:58","date_gmt":"2026-09-17T05:16:58","guid":{"rendered":"https:\/\/semqapps.com\/darkspeed\/sl\/kalkulator-prestav"},"modified":"2026-09-17T07:30:06","modified_gmt":"2026-09-17T05:30:06","slug":"kalkulator-prestav","status":"publish","type":"page","link":"https:\/\/semqapps.com\/darkspeed\/sl\/kalkulator-prestav","title":{"rendered":"Kalkulator prestav za kolo"},"content":{"rendered":"<p>Izberite sprednji zobnik, zadnji zobnik in pla\u0161\u010d, in kalkulator spodaj vam o tej prestavi pove tri stvari: kako hitro pelje pri dani kadenci, koliko palcev prestave ima in koliko metrov vas dejansko premakne en vrtljaj gonilke. Vse se prera\u010duna med tipkanjem.<\/p>\n<div class=\"calc\" data-imperial=\"1\" data-unit=\"mph\" data-decimal=\".\">\n  <h2 class=\"calc-title\" id=\"darkspeed-calculator\"><a href=\"https:\/\/semqapps.com\/darkspeed\/bike-gear-ratio-calculator\">Cadence and gearing calculator<\/a><\/h2>\n  <p class=\"calc-lead\">Set your gear and your cadence, then read off the speed. Everything updates as you type.<\/p>\n\n  <div class=\"calc-grid\">\n    <label class=\"calc-field\">\n      <span class=\"calc-label\">Cadence<\/span>\n      <span class=\"calc-input\">\n        <input type=\"number\" id=\"calc-cadence\" value=\"90\" min=\"20\" max=\"200\" step=\"1\" inputmode=\"numeric\" \/>\n        <span class=\"calc-suffix\">rpm<\/span>\n      <\/span>\n    <\/label>\n\n    <label class=\"calc-field\">\n      <span class=\"calc-label\">Chainring<\/span>\n      <span class=\"calc-input\">\n        <input type=\"number\" id=\"calc-chainring\" value=\"50\" min=\"20\" max=\"60\" step=\"1\" inputmode=\"numeric\" \/>\n        <span class=\"calc-suffix\">T<\/span>\n      <\/span>\n    <\/label>\n\n    <label class=\"calc-field\">\n      <span class=\"calc-label\">Sprocket<\/span>\n      <span class=\"calc-input\">\n        <input type=\"number\" id=\"calc-cog\" value=\"17\" min=\"9\" max=\"52\" step=\"1\" inputmode=\"numeric\" \/>\n        <span class=\"calc-suffix\">T<\/span>\n      <\/span>\n    <\/label>\n\n    <label class=\"calc-field\">\n      <span class=\"calc-label\">Wheel and tire<\/span>\n      <span class=\"calc-input\">\n        <select id=\"calc-wheel\">\n                    <option value=\"700x23c\"\n                  data-circ=\"2099\"\n                  >700 \u00d7 23C<\/option>\n                    <option value=\"700x25c\"\n                  data-circ=\"2111\"\n                   selected='selected'>700 \u00d7 25C<\/option>\n                    <option value=\"700x28c\"\n                  data-circ=\"2130\"\n                  >700 \u00d7 28C<\/option>\n                    <option value=\"700x32c\"\n                  data-circ=\"2155\"\n                  >700 \u00d7 32C<\/option>\n                    <option value=\"700x38c\"\n                  data-circ=\"2193\"\n                  >700 \u00d7 38C<\/option>\n                    <option value=\"29x2.25\"\n                  data-circ=\"2312\"\n                  >29 \u00d7 2.25<\/option>\n                    <option value=\"650bx47\"\n                  data-circ=\"2130\"\n                  >650B \u00d7 47 (27.5 \u00d7 1.85)<\/option>\n                    <option value=\"27.5x2.1\"\n                  data-circ=\"2168\"\n                  >27.5 \u00d7 2.10<\/option>\n                    <option value=\"26x2.1\"\n                  data-circ=\"2089\"\n                  >26 \u00d7 2.10<\/option>\n                    <option value=\"20x1.75\"\n                  data-circ=\"1552\"\n                  >20 \u00d7 1.75<\/option>\n                  <\/select>\n      <\/span>\n    <\/label>\n  <\/div>\n\n  <p class=\"calc-result\">\n    <output id=\"calc-out\" for=\"calc-cadence calc-chainring calc-cog calc-wheel\">\n      <strong id=\"calc-speed\">20.8<\/strong>\n      <span class=\"calc-unit\">mph<\/span>\n    <\/output>\n  <\/p>\n\n  <ul class=\"calc-secondary\">\n    <li>\n      <span class=\"calc-sec-label\">Gear inches<\/span>\n      <span class=\"calc-sec-value\" id=\"calc-inches\">77.8<\/span>\n    <\/li>\n    <li>\n      <span class=\"calc-sec-label\">Distance per pedal turn<\/span>\n      <span class=\"calc-sec-value\"><span id=\"calc-dev\">6.2<\/span> m<\/span>\n    <\/li>\n    <li>\n      <span class=\"calc-sec-label\">Rolling circumference<\/span>\n      <span class=\"calc-sec-value\"><span id=\"calc-circ\">2111<\/span> mm<\/span>\n    <\/li>\n  <\/ul>\n\n  <h3 class=\"calc-table-title\">The same gear at other cadences<\/h3>\n  <div class=\"calc-table-wrap\">\n    <table class=\"calc-table\">\n      <thead>\n        <tr>\n          <th scope=\"col\">Cadence<\/th>\n          <th scope=\"col\">mph<\/th>\n        <\/tr>\n      <\/thead>\n      <tbody id=\"calc-rows\">\n                <tr>\n          <td>60 rpm<\/td>\n          <td>13.9<\/td>\n        <\/tr>\n                <tr>\n          <td>70 rpm<\/td>\n          <td>16.2<\/td>\n        <\/tr>\n                <tr>\n          <td>80 rpm<\/td>\n          <td>18.5<\/td>\n        <\/tr>\n                <tr>\n          <td>90 rpm<\/td>\n          <td>20.8<\/td>\n        <\/tr>\n                <tr>\n          <td>100 rpm<\/td>\n          <td>23.1<\/td>\n        <\/tr>\n                <tr>\n          <td>110 rpm<\/td>\n          <td>25.5<\/td>\n        <\/tr>\n              <\/tbody>\n    <\/table>\n  <\/div>\n\n  <p class=\"calc-note\">The circumference is worked out from the ISO size printed on the tire wall: \u03c0 \u00d7 (rim diameter + twice the tire width). That runs about one percent above the tables built into bike computers, because a loaded tire is not a circle. For an exact figure, mark the valve, roll the bike forward one full turn with your weight on it, and measure the distance.<\/p>\n<\/div>\n<h2 id=\"kako-poteka-izracun\">Kako poteka izra\u010dun<\/h2>\n<p>Kolo nima menjalnika v avtomobilskem pomenu. Kar spremenite ob prestavljanju, je razmerje med dvema zobnikoma, in vse drugo iz njega sledi ra\u010dunsko. Ni skritega faktorja in ni\u010d se ne izgubi: vse gre na eno vrstico.<\/p>\n<p>Va\u0161e razmerje je preprosto sprednji zobnik, deljen z zadnjim. Petdeset zob spredaj proti sedemnajstim zadaj da 2,94, kar pomeni, da se zadnje kolo zavrti 2,94 krat na vsak vrtljaj gonilke. Pomno\u017eite to s potjo, ki jo kolo naredi v enem vrtljaju, in s \u0161tevilom vrtljajev gonilke na minuto, in imate svojo hitrost.<\/p>\n<p><strong>hitrost = kadenca \u00d7 (sprednji zobnik \u00f7 zadnji zobnik) \u00d7 obseg kotaljenja<\/strong><\/p>\n<p>Edina koli\u010dina, ki ni zapisana na kolesu, je zadnja, in to kalkulator izpelje namesto vas iz mere pla\u0161\u010da.<\/p>\n<h2 id=\"palci-prestave-in-pot-na-vrtljaj-gonilke\">Palci prestave in pot na vrtljaj gonilke<\/h2>\n<p>Golo razmerje 2,94 samo po sebi ne pove ni\u010d, ker zanemari kolo. Isto razmerje na gorskem kolesu s plati\u0161\u010di 26 palcev in na cestnem 700C da dve ob\u010dutno razli\u010dni prestavi. Zato kolesarji primerjajo prestave v enotah, ki kolo \u017ee vsebujejo.<\/p>\n<p>Palci prestave so starej\u0161i od obeh: premer, ki bi ga potreboval velociped z neposrednim pogonom, da bi na en pritisk pedala prevozil enako dale\u010d. Na prvi pogled muzejsko in vendar \u0161e vedno \u0161tevilka, ki jo vsi navajajo, ker naredi dve kolesi z razli\u010dnimi plati\u0161\u010di neposredno primerljivi. Pot na vrtljaj gonilke pove isto v metrih in si jo je la\u017ee predstavljati: prestava 78 palcev vas premakne za pribli\u017eno 6,2 metra na vsak polni vrtljaj gonilke.<\/p>\n<h2 id=\"kako-natancno-izmeriti-obseg-kotaljenja\">Kako natan\u010dno izmeriti obseg kotaljenja<\/h2>\n<p>Kalkulator izpelje obseg iz mere ISO, vtisnjene v bok pla\u0161\u010da: \u03c0 \u00d7 (premer plati\u0161\u010da + dvakrat \u0161irina pla\u0161\u010da). Pla\u0161\u010d 700 \u00d7 25C je ISO 25-622, torej \u03c0 \u00d7 (622 + 50) da 2111 mm. To je pregledno in preverljivo, \u010desar za tabele, vgrajene v ve\u010dino kolesarskih ra\u010dunalnikov, ni mogo\u010de re\u010di: med seboj se razlikujejo in ne navajajo vira.<\/p>\n<p>Je tudi pribli\u017eno odstotek previsoko, ker pla\u0161\u010d s kolesarjem na njem ni krog. \u010ce ho\u010dete pravo \u0161tevilko, jo izmerite s kotaljenjem: ozna\u010dite ventil spodaj, sedite na kolo, zapeljite naprej, dokler ventil spet ni spodaj, in izmerite med obema oznakama. Ponovite trikrat in povpre\u010dite. Ta ena meritev premaga vsako tabelo in je tudi vrednost, ki jo je smiselno vnesti v kolesarski ra\u010dunalnik, da se njegove razdalje ujemajo.<\/p>\n<h2 id=\"sest-prestav-izracunanih\">\u0160est prestav, izra\u010dunanih<\/h2>\n<p>Vseh \u0161est s pla\u0161\u010dem 700 \u00d7 25C, torej z obsegom 2111 mm. Hitrosti ra\u010dunajo s 90 rpm, kadenco, ki jo ve\u010dina zdr\u017ei na ravnem.<\/p>\n<table>\n<thead>\n<tr>\n<th>Prestava<\/th>\n<th>Za kaj je<\/th>\n<th>Palci prestave<\/th>\n<th>Pot na vrtljaj gonilke<\/th>\n<th>km\/h pri 90 rpm<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>34 \/ 28<\/td>\n<td>Strm vzpon<\/td>\n<td>32,1<\/td>\n<td>2,6 m<\/td>\n<td>13,8<\/td>\n<\/tr>\n<tr>\n<td>34 \/ 21<\/td>\n<td>Valovit teren<\/td>\n<td>42,8<\/td>\n<td>3,4 m<\/td>\n<td>18,5<\/td>\n<\/tr>\n<tr>\n<td>50 \/ 17<\/td>\n<td>Vo\u017enja po ravnem<\/td>\n<td>77,8<\/td>\n<td>6,2 m<\/td>\n<td>33,5<\/td>\n<\/tr>\n<tr>\n<td>50 \/ 14<\/td>\n<td>Hitra skupinska vo\u017enja<\/td>\n<td>94,5<\/td>\n<td>7,5 m<\/td>\n<td>40,7<\/td>\n<\/tr>\n<tr>\n<td>50 \/ 11<\/td>\n<td>\u0160print<\/td>\n<td>120,2<\/td>\n<td>9,6 m<\/td>\n<td>51,8<\/td>\n<\/tr>\n<tr>\n<td>42 \/ 16<\/td>\n<td>Tipi\u010den enoprestavnik<\/td>\n<td>69,4<\/td>\n<td>5,5 m<\/td>\n<td>29,9<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2 id=\"katera-kadenca-h-kateri-prestavi\">Katera kadenca h kateri prestavi<\/h2>\n<p>Kalkulator vam bo z veseljem povedal, da je 50 \u00d7 11 pri 110 rpm 63 km\/h. Ne bo vam povedal, da tega skoraj nih\u010de ne zdr\u017ei, in prav tu kalkulator prestav ni ve\u010d dovolj. Katero prestavo zavrtite, omejuje mo\u010d, ki jo imate, kadenca pa odlo\u010da, ali ta mo\u010d prihaja iz mi\u0161i\u010dne sile ali iz srca in plju\u010d.<\/p>\n<p>Na kratko: za ve\u010dino je uporabno obmo\u010dje 70 do 100 rpm, prava prestava pa je tista, ki vas v njem zadr\u017ei na terenu, po katerem vozite. \u010ce se na vzponu znajdete pod 70 rpm, je odgovor la\u017eja prestava in ne ve\u010dji napor. <a href=\"https:\/\/semqapps.com\/darkspeed\/sl\/kadenca-kolesarjenje\">Vodnik po kadenci<\/a> obravnava ta obmo\u010dja, to, kar so raziskave dejansko izmerile, in tri treninge za njihovo \u0161irjenje.<\/p>\n<h2 id=\"pogosta-vprasanja\">Pogosta vpra\u0161anja<\/h2>\n<p><strong>Katera prestava je dobra za cestno kolo?<\/strong> Za splo\u0161no vo\u017enjo gonilke 50\/34 s kaseto 11-32 pokrijejo skoraj vse: okoli 28 palcev spodaj za strme vzpone in okoli 120 zgoraj za spuste.<\/p>\n<p><strong>Kaj so palci prestave?<\/strong> Premer kolesa, ki bi ga potrebovalo kolo z neposrednim pogonom, da bi na en pritisk pedala prevozilo enako razdaljo. Na\u010din primerjave prestav med kolesi z razli\u010dno velikimi kolesi.<\/p>\n<p><strong>Kako izra\u010dunam hitrost iz kadence in prestave?<\/strong> Pomno\u017eite kadenco s prestavnim razmerjem in z obsegom kotaljenja. Pri 90 rpm s 50\/17 in kolesom 2111 mm to da 33,5 km\/h.<\/p>\n<p><strong>Ali \u0161irina pla\u0161\u010da spremeni mojo prestavo?<\/strong> Neznatno. Prehod s 25 mm na 32 mm doda pribli\u017eno 44 mm obsega, kar je okoli dva odstotka ve\u010d hitrosti pri isti kadenci in isti prestavi.<\/p>\n<p><strong>Kateri obseg naj vnesem v kolesarski ra\u010dunalnik?<\/strong> Tistega, ki ga izmerite s kotaljenjem kolesa s svojo te\u017eo na njem. Tabelari\u010dne vrednosti so obi\u010dajno odstotek preve\u010d optimisti\u010dne, kar je na 40 km pribli\u017eno 400 metrov.<\/p>\n<p><strong>Ali je te\u017eja prestava vedno hitrej\u0161a?<\/strong> Samo \u010de jo \u0161e vrtite pri razumni kadenci. Prestava, ki jo mlatite pri 55 rpm, dolgoro\u010dno daje manj mo\u010di kot la\u017eja, zavrtena pri 90.<\/p>\n<p><strong>Katero kadenco naj i\u0161\u010dem?<\/strong> Ve\u010dini najbolj ustreza med 70 in 100 rpm, pri \u010demer je okoli 90 rpm najpogosteje navedena referen\u010dna vrednost.<\/p>\n<aside class=\"ds-cta ds-cta--band\" id=\"get\"\t       data-cta-tag=\"page\"\n\t       aria-labelledby=\"ds-cta-1\">\n\t\t<h2 class=\"ds-cta-title\" id=\"ds-cta-1\">\n\t\t\tMount it. Ride it. <span class=\"text-cyan\">Read it at a glance.<\/span>\t\t<\/h2>\n\t\t\t\t<p class=\"ds-cta-lead\">DarkSpeed is a focused, distraction-free bike speedometer for iOS and Android.<\/p>\n\t\t\t\t    <div class=\"store-buttons\" data-placement=\"article_page\">\n      <a class=\"store-btn store-btn--apple\" href=\"https:\/\/apps.apple.com\/us\/app\/darkspeed-bike-speedometer\/id6780020629?pt=129025072&#038;ct=darkspeed_www&#038;mt=8\">\n        <svg class=\"store-icon\" viewBox=\"0 0 24 24\" fill=\"currentColor\" aria-hidden=\"true\"><path d=\"M17.564 12.625c-.022-2.244 1.832-3.318 1.916-3.371-1.044-1.526-2.667-1.735-3.245-1.76-1.382-.14-2.694.812-3.395.812-.7 0-1.78-.79-2.926-.768-1.506.022-2.894.874-3.668 2.22-1.564 2.71-.4 6.722 1.124 8.927.745 1.08 1.633 2.293 2.799 2.25 1.124-.046 1.55-.726 2.91-.726 1.36 0 1.742.726 2.93.703 1.21-.022 1.976-1.1 2.717-2.184.856-1.252 1.21-2.466 1.232-2.528-.027-.012-2.367-.91-2.394-3.575zm-2.225-6.575c.62-.752 1.04-1.798.926-2.844-.896.036-1.984.595-2.625 1.346-.575.666-1.078 1.733-.943 2.756 1 .078 2.022-.508 2.642-1.258z\"\/><\/svg>\n        <span>\n          <small>Download on the<\/small>\n          <strong>App Store<\/strong>\n        <\/span>\n      <\/a>\n      <a class=\"store-btn store-btn--google\" href=\"https:\/\/play.google.com\/store\/apps\/details?id=com.darkspeed.app&#038;referrer=utm_source%3Dsemqapps.com%26utm_medium%3Dreferral%26utm_campaign%3Ddarkspeed_www%26utm_content%3Den%26utm_term%3Dpage\">\n        <svg class=\"store-icon\" viewBox=\"0 0 24 24\" aria-hidden=\"true\">\n          <path fill=\"#34A853\" d=\"M3 20.5V3.5c0-.4.1-.7.3-1l10 10-10 10c-.2-.3-.3-.6-.3-1z\"\/>\n          <path fill=\"#FBBC04\" d=\"M16.8 12L20.4 9.9c.8.5 1.3 1.2 1.3 2.1s-.5 1.6-1.3 2.1L16.8 12z\"\/>\n          <path fill=\"#EA4335\" d=\"M13.3 12.5l3.5 3.5-12 6.7c-.5.3-1 .2-1.5-.2l10-10z\"\/>\n          <path fill=\"#4285F4\" d=\"M13.3 11.5L3.3 1.5c.5-.4 1-.5 1.5-.2l12 6.7-3.5 3.5z\"\/>\n        <\/svg>\n        <span>\n          <small>GET IT ON<\/small>\n          <strong>Google Play<\/strong>\n        <\/span>\n      <\/a>\n    <\/div>\n    \t<\/aside>\n","protected":false},"excerpt":{"rendered":"<p>Izra\u010dunajte hitrost, palce prestave in pot na vrtljaj gonilke iz zobnikov in pla\u0161\u010da. \u0160est obi\u010dajnih prestav ter kako natan\u010dno izmeriti obseg kolesa.<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":85,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-356","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/semqapps.com\/darkspeed\/wp-json\/wp\/v2\/pages\/356","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/semqapps.com\/darkspeed\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/semqapps.com\/darkspeed\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/semqapps.com\/darkspeed\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/semqapps.com\/darkspeed\/wp-json\/wp\/v2\/comments?post=356"}],"version-history":[{"count":1,"href":"https:\/\/semqapps.com\/darkspeed\/wp-json\/wp\/v2\/pages\/356\/revisions"}],"predecessor-version":[{"id":410,"href":"https:\/\/semqapps.com\/darkspeed\/wp-json\/wp\/v2\/pages\/356\/revisions\/410"}],"up":[{"embeddable":true,"href":"https:\/\/semqapps.com\/darkspeed\/wp-json\/wp\/v2\/pages\/85"}],"wp:attachment":[{"href":"https:\/\/semqapps.com\/darkspeed\/wp-json\/wp\/v2\/media?parent=356"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}