Muaj ntau tus neeg caij tsheb tshiab uas nyuam qhuav yuav ib lubtsheb kauj vab roobtsis paub qhov txawv ntawm 21-ceev, 24-ceev, thiab 27-ceev. Los yog tsuas paub tias 21-ceev yog 3X7, 24-ceev yog 3X8, thiab 27-ceev yog 3X9. Kuj muaj ib tug neeg nug seb lub tsheb kauj vab roob 24-ceev puas nrawm dua li 27-ceev. Qhov tseeb, qhov sib piv ntawm qhov ceev tsuas yog muab sijhawm rau cov neeg caij tsheb xaiv ntau dua. Qhov ceev nyob ntawm tus neeg caij lub zog ceg, kev ua siab ntev thiab kev txawj. Tsuav yog koj muaj lub zog loj, lub 21-ceev tsis qeeb dua lub tsheb kauj vab 24-ceev! Lub tsheb kauj vab roob tuaj yeem caij tau ntau mais?
Hauv kev xav, ntawm tib lub sijhawm pedaling cadence, lub tsheb kauj vab 27-ceev yuav khiav sai dua li 24-ceev. Tab sis qhov tseeb, nrog rau qhov sib piv iav siab, qhov kev pedaling yuav hnyav heev, thiab cadence yuav txo qis. Yog tias cadence txo qis, qhov ceev yuav txo qis. Qee zaum qee tus neeg pib tshiab yuav tsheb kauj vab roob thiab hais tias, "Kuv lub tsheb kauj vab zoo, vim li cas nws thiaj nyuaj rau pedal?" Qhov laj thawj yog tias nws tsis tau xaiv qhov sib piv iav uas haum rau nws thaum caij.

Ua ntej, cia peb saib qhov txawv ntawm 21-ceev, 24-ceev thiab 27-ceev:

21-ceev saw hlau & crank 48-38-28 flywheel 14~ 28

24-ceev saw hlau & crank 42-32-22 flywheel 11 ~ 30 (11 ~ 32)

27-ceev saw hlau & crank 44-32-22 flywheel 11 ~ 30 (11 ~ 32)

Qhov piv ntawm cov iav yog tus naj npawb ntawm cov iav faib los ntawm tus naj npawb ntawm cov flywheels

21-ceev qhov sib piv iav siab tshaj plaws 3.43, qhov sib piv iav tsawg kawg nkaus 1

Qhov sib piv iav siab tshaj plaws 24-ceev yog 3.82, qhov sib piv iav tsawg kawg yog 0.73 (0.69)

27-ceev qhov sib piv iav siab tshaj plaws 4, qhov sib piv iav tsawg kawg nkaus 0.73 (0.69)

Los ntawm qhov no peb tuaj yeem pom qhov txawv ntawm lawv. Lub 27-ceev thiab 24-ceev muaj qhov sib piv iav loj dua lossis me dua li 21-ceev, uas tuaj yeem ua rau koj caij sai dua thiab ua rau koj caij tsawg dua. Vim tias lub saw hlau 24-ceev tsis zoo ib yam li lub 21-ceev, lub saw hlau me dua tuaj yeem tau txais qhov sib piv iav sib dua, uas yog qhov zoo dua thaum nce toj. Lub tsheb kauj vab 24-ceev tuaj yeem ua tiav qhov sib piv kis ntawm 1.07 txawm tias nws siv qhov sib piv ceev 2X1. Yog tias lub flywheel yog 11 ~ 32, nws tuaj yeem ua tiav qhov sib piv kis ntawm 1 (qhov sib piv kis tsawg kawg nkaus ntawm 21-ceev yog 1). Yog li qhov zoo dua li lub tsheb kauj vab 21-ceev ntawm 24-ceev tsis yog tsuas yog nyob rau hauv lub iav ceev tshaj plaws, tab sis ntau dua nyob rau hauv lub iav qeeb tshaj plaws, uas ua rau nws yooj yim dua thiab muaj zog dua rau koj caij ntawm txoj kev roob. Tus neeg caij tsheb tshiab tsuas yog xav tias lub tsheb kauj vab 24-ceev ceev dua li lub tsheb kauj vab 21-ceev. Tej zaum ob peb tug neeg faib cov hniav ntawm txhua lub crank thiab cassette kom pom qhov txawv yog dab tsi.

Raws li lub tsheb kauj vab roob 27-ceev, nws lub flywheel feem ntau zoo ib yam li lub 24-ceev. Qhov txawv yog tias lub crank pem hauv ntej loj tshaj plaws tau hloov kho los ntawm 42 txog 44, uas yog qhov tsim nyog rau cov neeg uas muaj lub zog zoo. Lub tsheb kauj vab roob 24-ceev lossis lub tsheb kauj vab roob 27-ceev yog qhov txawv ntawm ntau qhov ntawm lub tsheb kauj vab uas tau hloov kho kom zoo dua nrog nws qib.