Repair guides › Wheels & Tires
Inspect rims for dents and cracks
The hoop the tire mounts on and the spokes pull on. Double-wall means a box section: two walls with a hollow between them, much stiffer than a single-wall rim. Internal width (often 19–25 mm) decides which tire widths sit well. The tire beads lock under the hooks on the rim edges. A center channel lets you push the beads down to get the tire off. Rim tape covers the spoke holes so they cannot cut the tube. The internal width decides which tire widths sit well: about 1.5× to 2× the internal width (a common rule of thumb; MTB tire makers allow wider, so check the tire maker’s chart). With disc brakes the rim never wears from braking, so it lasts until it is dented or cracked.
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Tools
- Shop rags + nitrile gloves: shop towels and nitrile gloves ($)
- Digital calipers: Clockwise Tools DCLR-0605 IP54 Digital Caliper ($$)
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Steps
- Clean the rims so you can see small cracks.
- Spin each wheel slowly and watch the rim edges against a fixed point (brake pad holder or a zip tie). A sudden jump means a dent or flat spot.
- Run a fingernail around both hook edges. A pinched or bent hook can let a tire blow off: replace the rim.
- Look closely at every spoke hole for hairline cracks radiating from the hole. A cracked rim must be replaced.
- Measure rim width at a few places with calipers. A big difference means a bulged or pinched rim wall: replace the rim. Rim brakes: check the braking surface too. If the wear-indicator groove or dot is gone, or the sidewall looks dished when you hold a straight edge across it, replace the rim before riding.
Diagram
Signs it needs doing
- Repeated flats on the inside of the tube (rim tape shifted or torn)
- Dent or flat spot after hitting a pothole
- Wobble that will not true out (bent rim)
- Cracks around spoke holes
- Tire bead will not seat evenly