How to find the right Bike Frames AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Bike Frames
- Fit by stack and reach
- Compare stack and reach in millimetres against your current bike. Do not rely on the nominal size label (S/M/L, 54 cm), which differs between brands. Size labels are not standardised, and a frame that doesn't fit can't be fixed with parts.
- Rear axle spacing and type
- Match the frame's standard to your wheels: quick release or thru-axle, and width (for example 130/135 mm QR, 142x12, 148x12 Boost, 120 mm track, 14 mm BMX). Hubs only fit the spacing and axle type they were built for.
- Bottom bracket standard
- Identify the shell: threaded (BSA 68/73 mm, T47, Spanish, Euro BMX) or press-fit (BB86, BB92, PF30, Mid BMX). Check your crankset spindle fits it. The bottom bracket shell decides which cranks and bearings you can use.
- Head tube and fork steerer
- Match the head tube to the fork steerer: straight 1-1/8 in or tapered 1-1/8 to 1.5 in, plus the headset type (integrated, zero-stack or external). A fork that doesn't match the head tube cannot be installed.
- Brake mounts
- Choose between rim brake (caliper, cantilever, V-brake or U-brake) and disc (flat mount or post mount), and match it to your wheels and brakes. Rim and disc systems are not interchangeable without a different frame.
- Seatpost diameter and tire clearance
- Note the seatpost diameter (for example 27.2, 30.9, 31.6 mm) and the maximum tire width the frame clears. These set which seatposts and droppers you can use and what terrain the bike can ride.
Brands that matter
- Surly: Steel frames with long-lasting, widely compatible standards.
- Soma: Affordable steel framesets for road, fixed gear and touring.
- Ritchey: Steel framesets with classic geometry, including road and cross.
- All-City: Steel track, cross and all-road frames.
What to avoid
- Unbranded carbon frames that have no stated safety testing.
- Buying before you confirm the BB, axle, head tube and brake standards match the parts you already own.
- Used carbon frames with impact damage or a history you can't verify.
Questions
Is buying a frame cheaper than a complete bike?
Usually not. Brands buy parts in bulk, so a frame-up build makes sense mainly when you are reusing parts or want a specific build.