The Ohlins HD645 is a rear STX 36 twin shock kit developed for Harley-Davidson Sportster XL models. Built around Ohlins damping know-how, it’s intended to improve chassis composure, grip and control without changing the character of the bike. As a twin-shock rear setup, it suits riders who want consistent, tunable suspension behaviour for road use.

Ohlins | Made to race, perfected to ride

Ohlins STX twin shocks focus on stable damping and predictable response over a wide range of conditions. The HD645 is designed as a direct rear twin-shock solution for Sportster XL fitment, aimed at riders wanting clearer feedback and better control from the back of the bike.

Shock design & features

This model uses an emulsion-style damping layout. The STX 36 architecture is designed to deliver consistent damping feel and improved rear-end control, helping the bike stay settled through braking zones, direction changes and uneven surfaces.

Tuning controls

The HD645 provides rebound damping adjustment and compression damping adjustment, allowing you to tailor how the shock reacts both when the rear extends and when it is being driven into the stroke. This makes it easier to balance comfort, support and traction for your load, tyres and riding conditions.

Who this shock is for

Suited to Sportster XL riders chasing firmer chassis control and more predictable rear grip compared with basic OE suspension. It’s also a good match if you ride briskly on back roads and want adjustment range to dial the bike in for your weight, road surfaces and typical pace.

Before you install

Confirm fitment for your exact Sportster XL year and model variant, and inspect linkage and mounting hardware condition before installation. After fitting, set rider sag and then fine-tune compression and rebound in small steps to reach a balanced feel front-to-rear.

SKU HD645
Model # S36E
Barcode # HD645
Brand Ohlins
Shipping Weight 5.0000kg
Shipping Size 0.300 x 0.300 x 0.500m
Type Units
See our Shipping Information See our Frequently Asked Questions
Position (Front or Rear) Rear Twin
Shock Length Eye to Eye (mm) 296.0
Spring Rate Standard 16.0 - 26.0 N/mm Progressive
Type Code S36E
Stroke Metal to Metal (mm) 71.0
Product Family STX 36 Twin
Fitted Spring 00380-04
Spring Colour Yellow

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