HomeBuying GuideDrivetrains​ ​and​ ​Groupsets​ ​-​ ​Made​ ​Easy

Drivetrains​ ​and​ ​Groupsets​ ​-​ ​Made​ ​Easy

A​ ​bike’s​ ​drivetrain​ ​comprises​ ​the​ ​cranks,​ ​front​ ​chainrings,​ ​rear​ ​cassette​ ​and​ ​the​ ​chain,​ ​as​ ​well  as​ ​the​ ​shifters​ ​and​ ​derailleurs​ ​–​ ​also​ ​known​ ​as​ ​mechs.​ ​Together​ ​they’re​ ​a​ ​hugely​ ​important  part​ ​of​ ​your​ ​bike.​ ​Groupsets​ ​are​ ​essentially​ ​the​ ​same​ ​thing,​ ​but​ ​often​ ​also​ ​include​ ​brakes.

Though​ ​simple​ ​in​ ​theory,​ ​some​ ​of​ ​today’s​ ​bicycle​ ​drivetrains​ ​are​ ​fantastically​ ​advanced.​ ​The majority​ ​are​ ​cable-activated,​ ​but​ ​at​ ​the​ ​top​ ​end​ ​you​ ​find​ ​electronic​ ​systems​ ​such​ ​as​ ​Shimano’s  Di2​ ​or​ ​SRAM’s​ ​eTap.

Whether​ ​you’re​ ​looking​ ​at​ ​the​ ​spec​ ​of​ ​components​ ​on​ ​a​ ​new​ ​bike​ ​you’re​ ​eyeing​ ​up,​ ​or​ ​ready  to​ ​upgrade​ ​either​ ​individual​ ​components​ ​or​ ​the​ ​whole​ ​groupset,​ ​it’s​ ​important​ ​to​ ​understand  the​ ​main​ ​terminology,​ ​how​ ​it​ ​works​ ​and​ ​how​ ​it​ ​all​ ​fits​ ​together.

HOW​ ​MANY​ ​GEARS​ ​DO​ ​I​ ​NEED?

While​ ​total​ ​number​ ​of​ ​gears​ ​is​ ​important,​ ​what’s​ ​more​ ​important​ ​is​ ​that​ ​the​ ​range​ ​of​ ​ratios​ ​is  right​ ​for​ ​you​ ​and​ ​your​ ​riding.​ ​Ideally,​ ​your​ ​smallest​ ​(shortest)​ ​gear​ ​should​ ​winch​ ​you​ ​up​ ​the  steepest​ ​hill,​ ​the​ ​biggest​ ​(tallest)​ ​should​ ​allow​ ​you​ ​to​ ​power​ ​back​ ​down​ ​(quickly​ ​enough!);​ ​yet  the​ ​steps​ ​between​ ​should​ ​not​ ​be​ ​too​ ​jarring.​ ​You​ ​may​ ​well​ ​achieve​ ​that​ ​with​ ​11​ ​or​ ​12​ ​gears​ ​on  a​ ​mountain​ ​bike,​ ​or​ ​20​ ​on​ ​a​ ​road​ ​bike,​ ​despite​ ​the​ ​potential​ ​for​ ​running​ ​up​ ​to​ ​33.

The​ ​range​ ​can​ ​be​ ​adjusted​ ​by​ ​fitting​ ​bigger​ ​or​ ​smaller​ ​chainrings​ ​on​ ​the​ ​cranks.​ ​A​ ​smaller​ ​ring  with​ ​fewer​ ​teeth​ ​lowers​ ​the​ ​gearing,​ ​and​ ​vice​ ​versa.​ ​Getting​ ​the​ ​gearing​ ​right​ ​on​ ​your​ ​next  new​ ​bike​ ​is​ ​important,​ ​but​ ​it’s​ ​a​ ​relatively​ ​cheap​ ​and​ ​easy​ ​modification​ ​if​ ​you​ ​want​ ​to​ ​change  later.

You​ ​can​ ​also​ ​change​ ​rear​ ​gearing​ ​–​ ​either​ ​by​ ​fitting​ ​a​ ​different​ ​cassette,​ ​or​ ​by​ ​replacing​ ​one  ratio​ ​with​ ​a​ ​large​ ​40/42-tooth​ ​‘expander​ ​ring’​ ​–​ ​but​ ​that​ ​can​ ​be​ ​more​ ​fiddly.​ ​All​ ​rear​ ​mechs  have​ ​a​ ​maximum​ ​gear​ ​they​ ​can​ ​physically​ ​accommodate,​ ​and​ ​a​ ​bigger​ ​gear​ ​may​ ​require​ ​a  new,​ ​longer​ ​mech.

WHICH​ ​IS​ ​THE​ ​BEST​ ​DRIVETRAIN?

Like​ ​any​ ​mods,​ ​gearing​ ​tweaks​ ​need​ ​a​ ​healthy​ ​base​ ​to​ ​be​ ​effective.​ ​So​ ​what​ ​are​ ​your​ ​options?  The​ ​answer,​ ​in​ ​a​ ​market​ ​dominated​ ​by​ ​the​ ​Japanese​ ​giant​ ​Shimano​ ​and​ ​its​ ​US​ ​adversary  SRAM,​ ​is​ ​almost​ ​infinite!​ ​Both​ ​companies​ ​group​ ​components​ ​into​ ​ranges​ ​with​ ​increasingly  high​ ​specs,​ ​and​ ​as​ ​parts​ ​can​ ​be​ ​mixed​ ​and​ ​matched​ ​across​ ​ranges,​ ​it​ ​helps​ ​to​ ​understand  what​ ​each​ ​one​ ​represents.

Shimano’s​ ​serious​ ​mountain​ ​bike​ ​componentry​ ​starts​ ​with​ ​Deore,​ ​rising​ ​through​ ​SLX​ ​to​ ​the  luxury​ ​XT​ ​and​ ​pro-level​ ​XTR.​ ​They​ ​also​ ​have​ ​a​ ​downhill-biased​ ​group​ ​Zee,​ ​and​ ​a​ ​pro-level  version,​ ​Saint.

SRAM’s​ ​equivalents​ ​are​ ​X5,​ ​X7/X9,​ ​then​ ​X0​ ​and​ ​XX.​ ​They​ ​also​ ​have​ ​a​ ​dedicated​ ​11-speed  range,​ ​which​ ​starts​ ​at​ ​NX​ ​and​ ​gets​ ​lighter​ ​and​ ​sharper​ ​through​ ​GX,​ ​X1,​ ​X01​ ​and​ ​finally​ ​XX1.​ ​At  the​ ​top​ ​of​ ​this​ ​range​ ​is​ ​the​ ​new​ ​Eagle​ ​12-speed​ ​tech.

Road​ ​bike​ ​drivetrain​ ​hierarchy​ ​is​ ​a​ ​little​ ​less​ ​complicated!​ ​Shimano’s​ ​serious​ ​offerings​ ​start​ ​at  Claris,​ ​rising​ ​through​ ​Sora,​ ​Tiagra​ ​and​ ​105​ ​to​ ​the​ ​impressive​ ​Ultegra​ ​and​ ​pro-level​ ​Dura-Ace.  Those​ ​top​ ​two​ ​tiers​ ​are​ ​where​ ​you​ ​find​ ​electronic​ ​Di2​ ​shifting.

SRAM’s​ ​rough​ ​equivalents​ ​start​ ​with​ ​the​ ​Tiagra-level​ ​Apex,​ ​before​ ​moving​ ​up​ ​to​ ​Rival,​ ​Force  and​ ​the​ ​pro-level​ ​Red.​ ​Red​ ​eTap​ ​is​ ​SRAM’s​ ​electronic​ ​shifting,​ ​and​ ​unlike​ ​Di2,​ ​it’s​ ​wireless.

DO​ ​I​ ​NEED​ ​A​ ​FRONT​ ​MECH?
While​ ​single​ ​front-ring​ ​(or​ ​1x,​ ​pronounced​ ​‘one-by’)​ ​drivetrains​ ​are​ ​appearing​ ​on​ ​the​ ​road,​ ​they  have​ ​the​ ​biggest​ ​benefits​ ​on​ ​mountain​ ​bikes.​ ​Removing​ ​the​ ​front​ ​mech,​ ​shifter​ ​and​ ​cable  drops​ ​significant​ ​weight,​ ​increases​ ​ground​ ​clearance,​ ​frees​ ​up​ ​bar​ ​space​ ​for​ ​dropper​ ​post  levers,​ ​and​ ​allows​ ​the​ ​use​ ​of​ ​‘narrow-wide’​ ​chainrings.​ ​These​ ​add​ ​huge​ ​chain​ ​security,​ ​i.e.  keeping​ ​it​ ​in​ ​place,​ ​without​ ​the​ ​weight​ ​of​ ​a​ ​chain​ ​device,​ ​because​ ​with​ ​no​ ​need​ ​for​ ​shifting,  the​ ​teeth​ ​can​ ​be​ ​extremely​ ​deep​ ​and​ ​close-fitting.

Doubles​ ​(or​ ​2x)​ ​remain​ ​common​ ​for​ ​mountain​ ​biking,​ ​ ​whereas​ ​triples​ ​are  generally​ ​only​ ​found​ ​on​ ​entry-level​ ​bikes​ ​with​ ​just​ ​8​ ​or​ ​9​ ​rear​ ​gears.

By​ ​contrast,​ ​most​ ​road​ ​bikes ​feature​ ​either​ ​two​ ​or​ ​three​ ​front​ ​rings,  combined​ ​with​ ​8​ ​or​ ​9​ ​gears​ ​at​ ​entry​ ​level,​ ​and​ ​10/11​ ​as​ ​prices​ ​rise.​ ​And​ ​the​ ​terminology​ ​is  different.​ ​The​ ​popular​ ​gearing​ ​combos​ ​on​ ​cranks​ ​are​ ​known​ ​as​ ​Triple,​ ​Compact​ ​and​ ​Standard.

Triple​ ​is​ ​self-explanatory​ ​–​ ​three​ ​rings,​ ​typically​ ​50/39/30t​ ​(the​ ​‘t’​ ​stands​ ​for​ ​’teeth’),​ ​which  provide​ ​a​ ​huge​ ​range.​ ​They’re​ ​ideal​ ​for​ ​touring​ ​and​ ​hilly​ ​all-round​ ​use.

Compacts​ ​are​ ​lighter​ ​with​ ​two​ ​rings,​ ​and​ ​combine​ ​the​ ​Triple’s​ ​big​ ​50t​ ​ring​ ​with​ ​a  middle-ground​ ​34t​ ​for​ ​climbing.​ ​They’re​ ​great​ ​for​ ​those​ ​riding​ ​for​ ​fitness,​ ​for​ ​everything​ ​from  training​ ​to​ ​sportives.  Less​ ​prevalent​ ​are​ ​‘super-compacts’:​ ​lower​ ​again,​ ​typically​ ​with​ ​48t​ ​and​ ​32t​ ​front​ ​rings,​ ​they’re  growing​ ​popularity​ ​along​ ​with​ ​cyclocross​ ​ ​and​ ​gravel​  bikes.

Standard,​ ​despite​ ​the​ ​name,​ ​features​ ​two​ ​bigger​ ​rings​ ​(53/39t)​ ​that​ ​only​ ​the​ ​most​ ​powerful  riders​ ​and​ ​road​ ​racers​ ​will​ ​feel​ ​comfortable​ ​pushing​ ​up​ ​significant​ ​inclines.

All​ ​the​ ​bikes​ ​on​ ​the​ ​Hargroves​ ​Cycles​ ​website​ ​have​ ​their​ ​gearing​ ​specification​ ​listed​ ​ and  often​ ​there​ ​are​ ​options​ ​on​ ​the​ ​same​ ​bike​ ​–​ ​and​ ​of​ ​course​ ​we’re​ ​glad​ ​to​ ​help​ ​you​ ​match​ ​the  best​ ​gearing​ ​for​ ​your​ ​riding.

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