1、AllAboutBicycleChainlineChainlineThisreferstohowstraightthechainrunsbetweenthefrontandrearsprockets.Ideally,bothsprocketsshouldbeinthesameplane,sothatthereisnosidewardmotionorstresstothechain.Thisconstitutes"perfectchainline".Inthecaseofderailergearedbicycles,thechainlineisnotperfectinmost

2、gears.Theworsethechainline,theworsethemechanicalefficientyofthedrivetrain."Correct"chainlineforaderailersystemisamatterofopinion,anddependsontheintendeduseofthebicycle.Therearetwo"simple"answerstothequestionofwhatconstitutesproperchainline:1. Oneviewisthatthemiddleoftheclustersho

3、uldlineupwiththemiddlechainring(orhalf-waybetweenthetwo,inthecaseofadouble2. Fromthepartsmanufacturers'pointofview,thechainlinedependsonthediameteroftheseattubewherethefrontderailermounts.Forfatterseattubeswherethefrontderailerisfarthertotheright,derailermanufacturerswantthechainlinetobefarthert

4、otherightalso,becausetheirmainpriorityisshiftingperformance,andtheirfrontderailershaveanoptimalchainlinewithrespecttotheedgeoftheseattube.Thisisparticularlyaconcerninthecaseofbicycleswithindexedfrontshifting.Fromtherider'spointofview,chainlineispartlydependentonhowyouaregoingtouseyourgears.Forin

5、stance,consideraroadtriplevsamountainbiketriple: Witharoadtriple,youmostlyusethetwobiggerrings,thegrannyisonlyoccasionallyused,andonlywiththelargerrearsprockets.Foraroadtriple,havingthecranksclose-inisgood,becauseitincreasestheusabilityofthebigring. Withamountainbike,thesmallringisusedmuchmoreoften,

6、andmustoftenbeusedwithfairlysmallsprocketstoavoidhavingtoshiftthefrontunderload.Formountainbikes,amoreoutboardchainwheelpositionisoftenpreferable.ChainlineStandards:ApplicationDimensionNotesRoadDouble43.5Shimanospec,measuredtothemidpointbetweentherings.withtypical5mmchainringspacing,thisputstheinner

7、at41mm,theouterat46mm.RoadTriple45Shimanospec,measuredtothemiddlering.MTBTriple47.5-50mmShimanospec,measuredtothemiddlering.47.5preferred,butforframeswithoversizedseattubes,thelongerdimensionmaybeneeded,becausethefattubeplacesthederailermechanismfarthertotheright.Track/CoasterBrakeTraditionalOne-Spe

8、edMostinternalgearhubs40.5-42mmOlderbikeswith110spacingwouldbeonthesmallerendofthisrangeNewerbikeswith120mmspacingnormallyuse42mmSinglespeedMTB52mmWiderchainlineneedforchainstayclearanceonMTBs.ThisisclosetothechainlineoftheouterringofatypicalMTBtripleRohloffSpeedhub54mm(58mmw/13tooth)SinglespeedMTBA

9、lternate47.5mmWhiteIndustriesENOhubsusethischainline,whichlinesupwiththemiddlepositionofatypicalMTBtriple.It'salsofairlyclosetotheouterpositionofatypical"road"double.ChainlineMeasurement-FrontChainlineismeasuredfromthecenterlineoftheframetothecenterofthechain.Youcanmeasurethefrontchain

10、linedirectlywithasimpleruler.Simplyholdtheruleragainsttheseattubeordowntubeandmeasurethedistancetothemiddleofthechainringteeth.Inthecaseoftriplechainwheelsets,measuretothemiddlechainring.Inthecaseofdoubles,measuretothehalfwaypointbetweenthetworings.ChainlineAdjustment-FrontIfyouneedtoadjustthefrontc

11、hainline,thereareseveraldifferentoptionstoaccomplishit:ChangetheBottomBracketMostbottombracketsmadesincethemid-'90saresymmetrical,theystickoutthesameamountoneachside.Ifyoureplaceyourpresentbottombracketwithonethatis,say,4mmshorter,itwillmovethechainline2mmtotheleft,becauseitwillbe2mmshorteroneac

12、hside.Ifyougothisroutetoanarrowerchainline,makesurethattherewon'tbeaclearanceproblembetweentheframeandthecrankorchainring.BottomBracketSpacerIfyouneedtoincreasethechainline(movethechainringtotheright)youcanusuallyaddaspacerwasherbetweentheright-sidebottombracketmountingring(orcup)andthebottombra

13、cketshelloftheframe.TheusualspacerforthisisaSturmey-Archersprocketspacer.ThesefitallthreadedbottombracketsexceptItaliansize.Sorry,Idon'tknowofanysourceforaspacerthatwillfitanItalian(36mm)bottombracket.ChainringSpacersForasinglechainring,youcanaddspacersbetweenthechainringandthecrankspider.Ifyour

14、chainringismountedontheoutsideofthespider,youcanmoveittotherigthtthisway.Ifit'smounteedontheinsideofthespider,youcanmoveittotheleftasshown.Thisusesthesame10mmI.D.spacersnormallyusedonrearhubaxles.Suitablespacersareavailablein1,2,and3mmthickness.Youmayneedtouselonger"double"stackbolts,e

15、speciallyforthe3mmsize.PhilWoodBottomBracketsPhilWoodBBsaresuperquality,availableinmanydifferentlengths,andtheyalsofeaturetheabilitytoadjustthechainlineoverarangeofseveralmillimeters.PhilWoodstuffisexpensive,butit'stheVeryBest.ChainlineMeasurement-Rear(Forbikesthatdonotusederailergearing)Tomeasu

16、rerearchainline: Measuretheframespacing(ortheover-lock-nutdimensionofthehub,whichshouldbethesame.)(Example:120mm) Dividetheresultinhalf.(Example:60mm) Measurethedistancefromtheinsideoftherearforkend(ortheoutsideoftheaxlelocknut)tothemiddleofthesprocket.(Example:18mm) Subtractthedropout-to-sprocketsp

17、acing(Example:18mm)fromthehalf-over-lock-nutdimension(Example:60mm)todeterminetheactualrearchainline(Example:42mm)Forfixed-gearorothersingle-speedhubs,seebelowforachartofdifferenthubsandsprockets,Withthischartyoucancalculatetherearchainlinebysimpleaddition.FixedSprocketsandSingleFreewheelsIhavemeasu

18、redaselectionoftracksprockets,singlefreewheelsandhubswithrespecttochainline(unitsaremillimeters.)The"Chainline"columnisthedistancefromthemmountingshouldertothecenterlineofthesprocketteeth.Tofiguretheactualchainlineforagivencombination,addthenumberfromthe"chainline"columnofthespro

19、cketorfreewheeltothecorrresponding"chainline"columnofthehubchosen.Fixed(Track)SprocketsModel/TypeNominalChainlineMeasuredTotalThreadWidth(FromShoulder)widththicknessThicknessCampagnolo3/32”7.02.08.07.8Campagnolo1/8”6.53.08.07.2E.A.I.3/32"38.05E.A.I.1/8"6.733.028.248.05M

20、icheQuickChangeSplined3/32"585/5151.97.727.3MicheQuickChangeSplined1/8"585/5153.07.727.3PhilWood3/32"5.862.37.017.01PhilWood1/8"6.053.027.567.06ShimanoDura-Ace3/32"6.492.117.557.55ShimanoDura-Ace1/8"7.053.058.587.7Soma3/32"6.371.867.37.3Soma1/8"6.93.008.46.9Su

21、ginoGigas1/8"7.03.08.57.5SunTourSuperbe3/32"6.222.267.357.35SunTourSuperbe1/8"6.933.058.467.5SurlyNew(2005)3/326.42.07.47.4SurlyNew(2005)1/8"5.937.47.4SurlyOld3/325.282.056.316.31SurlyOld1/8"5.072.76.426.42SingleSpeedFreewheelsModel/TypeNominalWidthChainline(FromShoulder)Mea

22、suredwidthACS3/32"7.962.16Shimano3/32"7.892.08Shimano1/8"8.673.0Tristar1/8"7.712.96WhiteIndustries3/32"8.732.17SingleSpeedandFixedGearHubsModel/TypeTrack/MTBOLDSpacingAdjustable?*一ChainlineCentertoShoulderLeftSideRightSideDrillingsAmbrosiolargeflangeTrack120?36FixedFixed32Ca

23、mpagnolosmallflangeTrack120Yes36PlainFixed28,32,362002CampagnoloC-RecordLargeflangeTrack120Yes35.9PlainFixed28,32,36GoldTecTrack120,130,135Yes39.5FixedFixed32,36I.R.O.Track120No36.0Fixed/Free32KogswellMTB135No45.3FixedFixed32MicheTrack120Yes36.3PlainFixed28,32,36On-OneFullMontyMTB135No43.3PlainFree3

24、2,36PhilWoodTrackTrack120,126,130No36.75PlainFixedFreeFixed28,32,36PhilWoodKISSOffMTB135No45.35Plain/FreeFixed/Free32,36ShimanoDura-Ace7700Track120Yes35.3Fixed28,32,36ShimanoDura-Ace7700SmallTrack120Yes35.3Fixed28,32,36FlangeShimanoDura-Ace7600LargeFlangeTrack120Yes35.4Fixed28,32,36SovosTrack112Yes3

25、3.5FreeFixed36SpotMTB135No47.25PlainFree28,32,36SurlyTrackTrack120Yes36.22FreeFixed32Surly1x1MTB135Yes46.5FreeFixed/FreeDrillingsSuzueBasicTrack117-120Yes34.74FreeFixed28,32,36SuzuePromax(cartridge)Track120Yes35.0FreeFixed28,32,36SuzuePromaxNJSTrack120Yes35.0FixedFixed28,32,36VanDessellMTB135No45.9F

26、reeFixed32WhiteIndustriesENOTrack/MTB126,130,135No391FreeFixed28,32,36ChainlineAdustement-RearThereareanumberofoptionsforadjustingrearchainlineonbikeswithasinglerearsprocket:AxleRe-Spacing/Re-DishingThisistheusualwaytogoforconvertingbikesfromamulti-speedderailersetuptoasingle-speedfixed-gearorfreewh

27、eeldrive.Thespacersarelocatedjustbehindtheouterlocknuts,betweenthelocknutsandthecones(orthebearingmountingnuts,ifyourhubusescartridgebearings.)Youwillneedconewrenchesandageneralunderstandingofhubbearingadjustmenttodothisjob.Assumingtherearhub'sspacingalreadymatchesyourframe'sspacing,youcanta

28、kespacerwashersfromonesideofthehubandmovethemtotheotherside,thusshiftingtheentirehubfromsidetoside.Inthecaseofahuboriginallymeantforamulti-speedfreewheel,thereisusuallyaratherthickspacerontheright(freewheel)sideofthehub.Youcanreplacethiswithastackofthinnerspacerwashersthatadduptothesameoverallthickn

29、ess,thendistributethewashersfromsidetosideasneededtogetthechainlinewhereyouneedittobe.Onceyouhavedonethis,you'llneedtore-dishthewheelbyadjustingthespokes.Thisisabitoftrouble,but,inthecaseeofmulti-to-single-speedconversion,there-dishingactuallyresultsinmakingthewheelmuchstrongerthanitwas.Ifyou

30、9;reusingaflip-flophub,re-spacingtheaxlewilllikelymaketheflip-flopfeatureunsuable,unlessyoualsouseadoublechainringinfront.SprocketDishingMostinternal-gearhubshave"dished"sprocketsthatcanbeinstalledeitherdishedin,orout,providingachoiceoftwodifferentchainlines.Fixed-gearsprocketsareusuallyintendedtobeinstalledwiththeflangefacinginward,sotheteethareoutboard.However,inmanycases,itispossibletoflipafixed-gearsprocketoverifyouneedtomovetherearchainlinetotheleft.SpacingWashersSturmey-Archerinternal-gearhubsgenerallyhavetwo1/16"(1.6