USED BICYCLE CHECKLIST BUYING GUIDE FOR ALUMINUM

Frame-set: In aluminum frames, look for significant dents. These can act as failure points. Carefully check the lugs or welds where the frame is joined together. Welds should be even. Cracking of any kind is a show-stopper. So are bends at the dropouts (where the wheels attach to the frame). There should be no play in the front fork, in other words, no wiggling.

Saddle or Seat: There should be no play whatsoever. Verify that the seat post clamp is free of cracks or obvious distress.

Brakes: Check for worn or dried-out brake pads. Look for cracked or bent brake levers.

Drive-train: Wiggle the crank-set. Side-to-side play indicates worn bearings or an improperly adjusted bottom bracket. The same applies to pedals. If possible, spin the free-wheel or cassette and listen for the chatter of broken bearings. Lift the rear wheel and verify that shifting is crisp through all gears. You should be able to shift into the largest and smallest rear gear without the chain jamming or becoming un-shipped. On bicycles with rear derailleurs, inspect the rear brake hanger for bends or cracking.

USED BICYCLE CHECKLIST BUYING GUIDE FOR CARBON FIBER

When inspecting a used carbon fiber bicycle, prioritize checking for cracks in the frame, especially around welds and high-stress areas, along with signs of impact damage, wear on components like the seat post, and proper functionality of all shifting and braking systems; always consider having a professional bike mechanic inspect the bike before purchase, particularly if you are unsure about any potential damage.

Key areas to inspect on a used carbon bike:

Frame:

• Cracks:

  Carefully examine the entire frame, including the top tube, down tube, seat tube, chain-stays, and head tube for any visible cracks, even tiny hairline fractures.

• Impact damage:

  Look for dents, chips, or areas where the paint is significantly damaged, as these could indicate underlying carbon fiber damage.

• Seat post insertion area:

  Check for wear marks or signs of excessive play where the seat post enters the frame.

• Dropouts:

  Inspect the rear dropouts for any signs of deformation or excessive wear.

• Carbon layup:

  Observe the carbon fiber pattern for consistency across the frame, uneven patterns could indicate potential manufacturing issues.

Components:

• Fork: Check the carbon fork for cracks, especially at the steerer tube and dropout areas.

• Stem and handlebars: Look for any signs of bending or damage on the stem and handlebars.

• Brakes: Ensure brakes are functioning properly and the pads are not excessively worn.

• Shifters and derailleurs: Test all gears for smooth shifting and proper functionality.

• Cassette and chain: Check for excessive wear and rust on the cassette and chain.

• Wheels: Inspect the wheels for bent spokes, damaged rims, and worn tires.

• Saddle: Check the saddle for wear and tear, especially if it is significantly damaged.

BICYCLE TUBE: SCHRADER VS. PRESTA VALVE - UNDERSTAND THE DIFFERENCE

Schrader Valve

The Schrader valve is a pneumatic (containing pressurized air or gas) tire valve found on almost all motorized vehicles including cars, motorcycles, and tractors. On bikes, Schrader valves are most often found on low-end hybrid bikes, mountain bikes, and kids' bikes.

Schrader valves are significantly wider than Presta valves, the valve core is situated inside the threaded outer - in the image above, the core is the silver section inside the more golden-colored threaded outer. As a result of all this, the valve head is a different shape, which means that a Schrader valve and Presta valve need different pump attachments - a wider attachment for Schrader, and a narrower one for Presta.

Presta valve

The Presta valve is narrow and can be found on almost all modern-day road bikes, as well as mid- to high-end mountain bikes, cyclocross bikes, gravel bikes, and more.

You’ll notice the difference in a Presta valve right away – you can’t miss it. It is much skinnier and pointed at the top, because rather than being hidden under a covering of plastic, a Presta valve core is right at the top of the valve itself. This exposed nature does make the valve core more prone to being bent or damaged, so take extra care when pumping up your tyres.

Presta valves also perform better over time compared to Schrader valves, in that they hold air more effectively and don’t degrade as quickly. They can also hold higher pressures, which makes them a must for track cycling where tyre pressures typically exceed 120psi.