10 Tips for Buying a New Bike Frame
The frame is the heart of your bike — everything else bolts to it. Whether you're building from scratch or replacing a cracked frame, these ten tips will save you money and mistakes.
Get the size right first
Frame size trumps everything. Use the manufacturer's size chart against your height and inseam, and if you can, check the stack and reach figures — they describe the fit better than a "56cm" label, which varies by brand.
Match the frame to how you ride
Endurance, race, gravel, or trail geometry all feel completely different. Be honest about the riding you actually do, not the riding you imagine — a twitchy race frame is miserable on a long café ride.
Understand the material trade-offs
Aluminium — affordable, stiff, durable. Carbon — light and tuneable but costlier and damage-sensitive. Steel — comfortable and repairable, heavier. Titanium — durable and comfy, premium price. None is "best"; each suits a different priority.
Check the wheel and axle standards
Modern frames use thru-axles (12mm common) rather than old quick-release. Confirm the axle standard and hub spacing match your wheels — a mismatch means new wheels or an expensive adapter.
Confirm the bottom bracket standard
Bottom bracket standards are a minefield (threaded, press-fit, T47…). Check which your frame uses and whether your crank is compatible before you buy.
Check brake mount compatibility
Disc frames use flat mount or post mount calipers, and are built for a specific rotor size. Rim-brake frames are increasingly rare. Match the frame to the brakes you plan to run.
Look at cable routing
Fully internal routing looks clean but makes maintenance harder; external routing is easier to work on. Decide which you value — it affects every future service.
Inspect a used frame carefully
Buying used? Check carbon for cracks (tap-test dull spots), check alloy/steel for dents and corrosion at welds, and check the dropouts and head tube for damage. If in doubt on carbon, it isn't worth the risk.
Factor in the "hidden" build costs
A bare frame needs a headset, bottom bracket, and often a seat clamp — budget for them. A frame that's "cheap" can become expensive once it's rolling.
Buy from a trusted source
A frame is a long-term purchase — buy somewhere with clear condition descriptions and buyer protection. On Cog, used frames list the size, material and standards up front, and every purchase is covered by buyer protection.
Frequently asked questions
What's the most important thing when buying a frame?
Correct size and geometry for your riding — get that wrong and no upgrade fixes it.
Is a carbon frame worth it?
For weight and ride-tuning, yes — but only if the fit and standards are right and you'll look after it.
How do I know if a used frame is safe?
Inspect for cracks, dents and corrosion; be especially cautious with carbon, where hidden damage can be dangerous.
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