23–24 January 2027 · Veliky Novgorod
ЗИМНИЕ ВЫХОДНЫЕ ВЕЛОКРОССА · 3ВВ
Два дня ТИПАЦИКЛОКРОССА: Cyclocross, Gravel, Fixed gear, МТБ и беговой кросс. Один день или оба.
How to match a bottom bracket to a frame and crankset
“For a 24 mm spindle” describes only part of the problem. A bottom bracket must fit both the frame and the specific crankset. This checklist helps you gather the information for selection; it is not a universal adapter chart.
1. Identify the frame interface
Find the frame model, year and size, then its manual. Record the complete shell standard, width, and thread or press-fit bore specification. “Threaded bottom bracket” or “wide shell” is not a sufficient description.
If the specification conflicts with the installed part, check the repair history. Do not press out a working bottom bracket just to investigate: ask a workshop to measure a dismantled assembly if you lack the tools and experience.
2. Identify the crank interface
Record the full crankset code, spindle specification, version and required chainline from its manual. Diameter alone is insufficient: spindle length, stepped sections and preload design matter too. A shared family name does not make road and MTB versions equivalent.
Selection joins two specifications: frame → bottom-bracket outer interface; crankset → inner interface and assembled width. Both sides need explicit confirmation in the manufacturers’ documentation.
3. Check the complete assembly
Record the bottom-bracket part number and all required cups, sleeve, seals, spacers and preload parts. Their order and quantity come from the instructions for the actual shell width and crankset. There is no universal rule to add a spacer on each side.
Separately confirm chainline, chainring and crank clearance to the frame, and front-derailleur compatibility where applicable. A spindle passing through the bearings does not establish a correct installation.
4. When selection is still unresolved
Pause the order if the shell standard, crank version or spacer arrangement is unknown. Ask the manufacturer for an approved part number and documentation for your pair. An unspecified “adapter” does not resolve the issue.
Keep the old markings and assembly details for diagnosis, but do not treat the previous installation as proof of correctness. Follow the chosen components’ instructions for torque, lubrication and installation. This guide deliberately supplies no universal settings.
5. A worksheet for the workshop
“Frame __, year __, shell standard __, width __. Crankset __, documented spindle specification __, chainline __. Current bottom bracket __. I need a replacement while keeping the crankset. Please specify the part number, complete spacer arrangement, source diagram and clearance checks. Unknown: __.”
Use the workshop directory to find a service provider. The gearing calculator can help with chainring changes, but cannot identify a bottom-bracket standard or validate interfaces.
