OLN

Over Lock Nuts. The critical dimension when describing the width of a wheel. Sometimes referred to as ‘OLD’ or ‘over-lock-nut diameter’. Different rear wheel designs have different OLN dimensions.

Here are some examples of OLN dimensions on rear wheels:

• Sturmey Archer hubs are 116mm OLN
• six speed derailleur wheels are 126mm OLN
• modern road bike wheels with 7 or more rear sprockets are 130mm OLN
• modern mountain bikes and some touring bikes are 135mm OLN

Front wheels for adult bikes are now standardised at 100m OLN whereas some vintage bikes have a slightly smaller OLN dimension.

If replacing a wheel it’s important to find one with the same OLN measurement otherwise it won’t fit between the dropouts.

Variation in OLN dimensions means that wheel spindles vary in length.