32spoke

The idea was to build a tool to help me re-build my long-hauled front wheel. Then it became a webapp helps everyone whose wants to build a wheelset by herself/himself.

I hope this help you calculate spoke length for the next build

live one 32spoke

wheel variables

1. Hub

• Hub name
• Hub weight
• Left flange diameter
• Right flange diameter
• Left flange to center
• Right flange to center
• Spoke hole diameter

2. Rim

• Rim name
• Rim weight
• Rim ERD
• Offset spoke bed(OSB)
• Max rim tension

3. Lacing

• Spoke name
• Number of spokes
  • 16
  • 18
  • 20
  • 24
  • 28
  • 32
  • 36
• Lacing pattern
  • 1x
  • 2x
  • 3x

Color

• Option 1

  /* SCSS RGB */
  $ruby-red: rgba(163, 22, 33, 1);
  $beau-blue: rgba(191, 219, 247, 1);
  $indigo-dye: rgba(5, 60, 94, 1);
  $metallic-seaweed: rgba(31, 122, 140, 1);
  $amaranth-red: rgba(219, 34, 42, 1);
  

• Option 2

  /* SCSS RGB */
  $eerie-black: rgba(24, 24, 24, 1);
  $silver: rgba(196, 196, 196, 1);
  $white: rgba(255, 255, 255, 1);
  $aureolin: rgba(247, 232, 19, 1);
  $madder-lake: rgba(208, 51, 58, 1);
  

How the spoke length calculated

Note: only works for J-bend spokes at the moment. Not suit for Straight-pulll spokes

• d = distance from the center of hub (along the axis) to flange, for instance of a rear hub, cTLF and cTLR are different
• r1 = the radius of circle of flange holes, equals to PCD/2
• r2 = half of Effective Rim Diameter (ERD), or the diameter the ends of the spokes make in a built wheel of the rim
• r3 = radius of spoke holes in the flange, for example 2.6 mm,
• m = number of spokes to be used for one side of the wheel, equals to half of the "spokeNumber"
• k = number of crossings per spoke,

// spokeCalculator.js
const spokeCalculator = (d, r1, r2, r3, m, k) => {
	const angleCalculator = (crossing, spokeNumber) => {
		const angle = (360 * crossing) / spokeNumber
		return angle
	}

	const roundNumberToTowDecimal = (num) => {
		return Math.round((num + Number.EPSILON) * 100) / 100
	}

	const angle = angleCalculator(k, m)

	let spokeLength =
		Math.sqrt(d * d + r1 * r1 + r2 * r2 - 2 * r1 * r2 * Math.cos(angle)) - r3

	spokeLength = roundNumberToTowDecimal(spokeLength)

	return spokeLength
}

export default spokeCalculator

Reference

• Round to at the most 2 decimal places on if necessary