[{"data":1,"prerenderedAt":401},["ShallowReactive",2],{"article-en-measure-bottom-bracket":3,"articles-en":304},{"id":4,"title":5,"applies_to":6,"author":8,"body":9,"confidence":280,"description":281,"extension":282,"faq":283,"meta":290,"navigation":291,"path":292,"seo":293,"sources":294,"stem":299,"test_bike":300,"topic":301,"updated":302,"__hash__":303},"content_en\u002Fen\u002Fwissen\u002Fmeasure-bottom-bracket.md","Measure Your Bottom Bracket for a Mid-Drive",[7],"mid","fabio-gentsch",{"type":10,"value":11,"toc":269},"minimark",[12,24,29,47,50,54,102,106,184,187,191,194,202,206,236,240,253,256,260,263],[13,14,15,16,23],"p",{},"For a mid-drive you measure two things on the bottom bracket shell: its width and its inner diameter, and you check whether there is a thread. Bafang BBS and Tongsheng TSDZ fit BSA shells 68 to 73 mm wide. Pressfit (BB86\u002FBB92) needs an adapter (",[17,18,22],"a",{"href":19,"rel":20},"https:\u002F\u002Ffasterbikes.eu\u002Fen\u002Fconfigurators\u002F",[21],"nofollow","fasterbikes",").",[25,26,28],"h2",{"id":27},"what-you-need","What you need",[30,31,32,36,44],"ul",{},[33,34,35],"li",{},"Calipers, or in a pinch a ruler or tape measure",[33,37,38,39,43],{},"Bottom bracket tool and crank puller if you want to remove the old bottom bracket (see ",[17,40,42],{"href":41},"\u002Fen\u002Fknowledge\u002Ftools","tools",")",[33,45,46],{},"A torch and a rag",[13,48,49],{},"Take a photo of the bottom bracket area before you measure. It helps later if you need to ask a dealer.",[25,51,53],{"id":52},"step-by-step","Step by step",[55,56,57,64,78,84,90,96],"ol",{},[33,58,59,63],{},[60,61,62],"strong",{},"Remove crank and bottom bracket."," Without the bearing out you cannot see what sits in the shell. If you only want a quick look the outside view often suffices, but the measurement is less accurate.",[33,65,66,69,70,73,74,77],{},[60,67,68],{},"Measure shell width."," The shell is the tube running across the frame that holds the bearing. Measure between the two outer edges, without cups. Common values are ",[60,71,72],{},"68 mm"," and ",[60,75,76],{},"73 mm",". Much less or clearly more points to special cases, such as fat bike shells of 100 or 120 mm.",[33,79,80,83],{},[60,81,82],{},"Check for a thread."," Look into the shell. Can you see threads? Then it is a threaded bottom bracket.",[33,85,86,89],{},[60,87,88],{},"Measure the inner diameter."," Measure the opening of the shell. A rule of thumb: on BSA the inner diameter at the thread is around 34 to 35 mm. Pressfit shells are clearly wider.",[33,91,92,95],{},[60,93,94],{},"Identify the type"," (see table).",[33,97,98,101],{},[60,99,100],{},"Check space for the motor."," See whether anything near the shell is in the way, such as a chainstay or a welded mount.",[25,103,105],{"id":104},"which-type-is-it","Which type is it?",[107,108,109,125],"table",{},[110,111,112],"thead",{},[113,114,115,119,122],"tr",{},[116,117,118],"th",{},"Type",[116,120,121],{},"Feature",[116,123,124],{},"Mid-drive",[126,127,128,140,151,162,173],"tbody",{},[113,129,130,134,137],{},[131,132,133],"td",{},"BSA 68",[131,135,136],{},"thread, shell 68 mm wide",[131,138,139],{},"usually fits directly",[113,141,142,145,148],{},[131,143,144],{},"BSA 73",[131,146,147],{},"thread, shell 73 mm wide",[131,149,150],{},"usually fits directly, maybe different spacers",[113,152,153,156,159],{},[131,154,155],{},"Pressfit (BB86\u002FBB92)",[131,157,158],{},"no thread, bearing pressed in",[131,160,161],{},"only with adapter",[113,163,164,167,170],{},[131,165,166],{},"BB30",[131,168,169],{},"no thread, large bearing, 42 mm bore (rule of thumb)",[131,171,172],{},"usually adapter or own variant",[113,174,175,178,181],{},[131,176,177],{},"Fat bike (100\u002F120 mm)",[131,179,180],{},"very wide shell",[131,182,183],{},"own motor variant needed",[13,185,186],{},"The BSA values of 68\u002F73 mm and the adapter statement for Pressfit come from the source named; the BB30 details are assumptions. Ask the dealer before buying whether your shell is supported.",[25,188,190],{"id":189},"recognising-pressfit-and-bb30","Recognising Pressfit and BB30",[13,192,193],{},"With Pressfit or BB30 you see no thread turns. The cups sit in a smooth shell and are pressed in. Abbreviations are often printed on the bearing or listed in the frame specification. The frame manufacturer's website or the print on the bearing helps.",[13,195,196,197,23],{},"On a carbon frame with a Pressfit bottom bracket, keep your hands off. Carbon is not recommended as a conversion frame anyway (",[17,198,201],{"href":199,"rel":200},"https:\u002F\u002Fwww.giga.de\u002Ftech\u002Fwer-billig-kauft-kauft-zweimal-diese-fehler-solltet-ihr-vermeiden-wenn-ihr-eurer-fahrrad-zum-e-bike-umbaut--01K0YYJEVGW05AE9TTBCPW0DAM",[21],"GIGA",[25,203,205],{"id":204},"what-else-matters","What else matters",[30,207,208,214,220,230],{},[33,209,210,213],{},[60,211,212],{},"Chain line and chainstay:"," The motor sits wider than the old bearing. Check that chain and chainstay still have clearance.",[33,215,216,219],{},[60,217,218],{},"Front derailleur:"," It usually goes. Plan for a single chainring.",[33,221,222,225,226,23],{},[60,223,224],{},"Coaster brake:"," The freewheel inside the motor often disables it (see ",[17,227,229],{"href":228},"\u002Fen\u002Fknowledge\u002Fcoaster-brake","coaster brake",[33,231,232,235],{},[60,233,234],{},"Frame shape:"," Not every frame accepts a mid-drive. Shell and tubes have to fit.",[25,237,239],{"id":238},"if-it-does-not-fit","If it does not fit",[13,241,242,243,247,248,252],{},"If your bottom bracket does not fit, you have three ways out: use an adapter (for Pressfit), pick another motor variant, or switch to a front or rear motor. The pros and cons are in ",[17,244,246],{"href":245},"\u002Fen\u002Fknowledge\u002Fmotor-types","motor types compared",". If you are unsure between mid-drive and hub motor, see ",[17,249,251],{"href":250},"\u002Fen\u002Fknowledge\u002Fmid-drive-vs-hub-motor","mid-drive or hub motor",".",[13,254,255],{},"Before ordering, measure twice, order once.",[25,257,259],{"id":258},"how-reliable-is-this","How reliable is this?",[13,261,262],{},"BSA 68 to 73 mm for Bafang BBS and Tongsheng TSDZ and the adapter need for Pressfit come from one source; the measuring procedure, the diameter rules of thumb and the BB30 and fat bike details are experience or assumptions that Fabio is still checking.",[13,264,265],{},[17,266,268],{"href":267},"\u002Fen\u002Fconfigurator","Does a conversion fit your bike?",{"title":270,"searchDepth":271,"depth":271,"links":272},"",2,[273,274,275,276,277,278,279],{"id":27,"depth":271,"text":28},{"id":52,"depth":271,"text":53},{"id":104,"depth":271,"text":105},{"id":189,"depth":271,"text":190},{"id":204,"depth":271,"text":205},{"id":238,"depth":271,"text":239},{"id":258,"depth":271,"text":259},"assumption","How to measure shell width and bore of your bottom bracket and tell BSA 68\u002F73, Pressfit and BB30 apart. Step by step for a mid-drive motor.","md",[284,287],{"q":285,"a":286},"Which bottom brackets fit Bafang BBS and Tongsheng TSDZ?","Both fit BSA shells 68 to 73 mm wide. Pressfit shells such as BB86 or BB92 need an adapter.",{"q":288,"a":289},"How do I recognise Pressfit?","Pressfit has no thread in the shell, the cups are pressed in. The opening is clearly wider than on a threaded bottom bracket.",{},true,"\u002Fen\u002Fwissen\u002Fmeasure-bottom-bracket",{"title":5,"description":281},[295,297],{"title":296,"url":19},"fasterbikes: configurators",{"title":298,"url":199},"GIGA: mistakes when converting to an e-bike (German)","en\u002Fwissen\u002Fmeasure-bottom-bracket",null,"tretlager-messen","2026-11-09","YkZBczYRfb8fWFj17hgFgDLxm_M0AstgIup8h8j4mQk",[305,312,318,324,330,336,342,348,354,362,364,370,376,383,389,395],{"path":306,"title":307,"description":308,"topic":309,"applies_to":310,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fbattery","E-Bike Battery for a Conversion: Position, Space, Range","Where the battery fits on a converted bike, how to measure the space, what branded cells bring, real-world range and how to dispose of it.","akku",[311],"all",{"path":313,"title":314,"description":315,"topic":316,"applies_to":317,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fbrakes","Brakes for an E-Bike Conversion: What You Need","Rim or disc, cut-off levers and sensors: which brakes are enough for a 250 W pedelec and when an upgrade is needed.","bremsen",[311],{"path":319,"title":320,"description":321,"topic":322,"applies_to":323,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fcoaster-brake","Coaster Brake and E-Bike Conversion: What Works","A coaster brake is the most common deal-breaker. Which motors work, where coaster-brake variants exist and when to leave it.","ruecktrittbremse",[311],{"path":325,"title":326,"description":327,"topic":328,"applies_to":329,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fcommon-problems","Common Problems After an E-Bike Conversion","Axle spinning, broken spokes, motor cutting out, jerky starts, fast chain wear: causes and fixes from everyday conversions.","haeufige-probleme",[311],{"path":331,"title":332,"description":333,"topic":334,"applies_to":335,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fconvert-bike-to-ebike","Convert a Bike to an E-Bike: Overview and Steps","What a conversion costs, which motor fits, what the law says and when you should buy a used e-bike instead. An honest overview from the workshop.","fahrrad-zum-e-bike-umbauen",[311],{"path":337,"title":338,"description":339,"topic":340,"applies_to":341,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fcosts","What Does an E-Bike Conversion Really Cost?","Cost items at a glance: kit EUR 400 to 1,700, brakes, tools, small parts. Plus the comparison with used and new (about EUR 2,500) and the cost calculator.","kosten",[311],{"path":343,"title":344,"description":345,"topic":346,"applies_to":347,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fframe-and-weight","Frame and Weight: Which Bike Suits a Conversion","Steel and aluminium are usually fine, carbon is not. Plus the magnet test, total weight, warranty and the wear parts to replace before converting.","rahmen-und-gewicht",[311],{"path":349,"title":350,"description":351,"topic":352,"applies_to":353,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fglossary","E-Bike Conversion Glossary: Terms Explained","Rated power, volts, watt-hours, newton metres, PAS, torque sensor, Higo and Julet, controller and display: the glossary for e-bike conversions.","begriffe",[311],{"path":355,"title":356,"description":357,"topic":358,"applies_to":359,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fhub-spacing","Hub Spacing and Axles for an E-Bike Conversion","How to measure hub spacing, quick release versus thru-axle, spreading 130 to 135 mm on steel frames and what to watch with dropouts.","einbaubreite",[360,361],"front","rear",{"path":292,"title":5,"description":281,"topic":301,"applies_to":363,"confidence":280,"updated":302,"author":8},[7],{"path":365,"title":366,"description":367,"topic":368,"applies_to":369,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fmid-drive-vs-hub-motor","Mid-Drive or Hub Motor: What Suits You?","Ride feel, hills, gears, installation and cost compared, with a clear guide to when a mid-drive and when a front or rear hub motor makes sense.","mittelmotor-oder-nabenmotor",[7,360,361],{"path":371,"title":372,"description":373,"topic":374,"applies_to":375,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fmotor-types","E-Bike Conversion Motor Types Compared","Front, rear and mid-drive motors, friction rollers and seat-tube motors compared: feel, installation, cost and which bikes suit which.","motorarten",[311],{"path":377,"title":378,"description":379,"topic":380,"applies_to":381,"confidence":382,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fpedelec-law","Pedelec Law: 250 W, 25 km\u002Fh and Walking Assist","What a conversion may do legally: 250 W rated power, assist only while pedalling up to 25 km\u002Fh, walking assist up to 6 km\u002Fh and what lies beyond.","pedelec-recht",[311],"source",{"path":384,"title":385,"description":386,"topic":387,"applies_to":388,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Ftools","Tools for an E-Bike Conversion: The List","Which tools you need for front, rear and mid-drive conversions and what kits usually lack, above all the lockring tool.","werkzeug",[311],{"path":390,"title":391,"description":392,"topic":393,"applies_to":394,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Ftorque-arm","Torque Arm: When You Need One","Why the axle of a hub motor turns in the dropout, when you need a torque arm and how to fit it.","drehmomentstuetze",[360,361],{"path":396,"title":397,"description":398,"topic":399,"applies_to":400,"confidence":280,"updated":302,"author":8},"\u002Fen\u002Fwissen\u002Fwheel-sizes","Wheel Sizes and ETRTO for E-Bike Conversions","Inches are unreliable, ETRTO is not: how to read wheel size off the tyre and avoid the 635\u002F622 and 406\u002F451 traps.","laufradgroessen",[360,361],1794247507536]