RALTech | Measuring for Wheel Covers

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Measuring for RALTech Wheel Covers

Sketch

D-out is outside diameter of cover.
This will usually be 610mm to extend as far as the brake track. It could be less on a deep section rim, leaving more of the rim itself exposed. It could also be more, up to 630mm, if you're riding fixed and don't have a rear brake fitted.

D-in will define the maximum diameter for the fixings, which join the two covers together. For D-out and D-in, measure the full diameter, i.e. from one side to the other.

Measure D-out Measure D-in
Measuring D-out... ...and D-in

D1 and D2 are the parts of the hub where the centre of the wheelcover will locate, so they should be a reasonably snug fit to help centre the covers. D2 is often dictated by the freehub diameter, so is typically about 39mm, but D1 can vary a lot more.

Measure_D1
Measuring D1

H1 and H2 should be measured from the top of the spokes, i.e. the height where the centre of the wheel cover will rest. You will probably find it easier to calculate these heights by using some simpler measurements:-

1. Measure to the top of the spokes from the inside face of the dropout. Call this X1 and X2 for non-drive and drive side respectively. X2 is usually around 45mm, as this is mostly dictated by the width of the cassette. X1 can vary quite a lot dependent on the design of the hub.

Measure X1
Measuring X1

Measure X2
Measuring X2

2. Measure the width of the rim at the diameter (D-out) where the cover will sit. Call this W. It's usually about 20mm.

Measure W
Measuring W

3. Calculate.
   Assuming 130mm rear dropout (OLN) spacing,
   H1 = (130 - W)/2 - X1
   H2 = (130 - W)/2 - X2

Remember to take care with all these measurements; the better the measurement, the more likely the covers will fit perfectly first time.

Wheel Covers are available here.