The facts.
| Brand | Öhlins |
|---|---|
| Part Number | 66388-01 |
| Spring Rate | 71 N/mm |
| Free Length | 115 mm |
| Inner Diameter | 55 mm |
| Stroke | 71 mm |
| Construction | Tapered |
| Finish | Powder-coated black |
| Country of Origin | Sweden |
DescriptionThe whole story▼
Öhlins part number 66388-01 is a shock absorber spring rated at 71 N/mm, 115 mm long with a 55 mm inner diameter. A rear spring matched to rider and load keeps the chassis attitude where the factory intended it.
Key Features
- Öhlins part number 66388-01
- Powder-coated black
- Measured spring rate 71 N/mm
- Inner diameter 55 mm
- Free length 115 mm
- 71 mm of usable stroke
- Tapered-wound, constant rate
Manufacture and Tolerance
Anodising is hard-coat rather than decorative, which matters on a component exposed to road salt and stone chips. Each spring is set before it is measured, so it will not settle and lose rate in service. Öhlins manufactures in Upplands Väsby, north of Stockholm, and assembles and tests every unit there before it ships.
Size and Rate
At 115 mm free length and 55 mm inner diameter, this spring is dimensionally interchangeable with anything of the same size — the rate is what makes it a different part.
Where This Rate Belongs
Firm rates trade some small-bump comfort for support — the right trade on a good surface at speed. This end of the range suits heavier riders, two-up use, or a machine ridden hard enough that fork dive becomes the limit. Heavier riders, two-up use and track days all push the choice towards this end. Road surfaces are the hardest test of a spring rate, because the fork has to cope with both a smooth stretch and a broken one.
What the Rear Spring Decides
A shock absorber spring carries the whole rear of the machine through a linkage that multiplies its rate several times over — which is why the number on the spring looks so much larger than a fork rate. A rear spring is the cheapest part of the suspension and the one that decides the most. Rear spring rates run in the tens or hundreds of N/mm because the spring sits at the short end of that lever, not at the wheel.
Applications
Öhlins builds springs to dimensions rather than to model lists, so the question is always the same: does the diameter fit, does the length fit, and is the rate right for the rider? This is a service part in the proper sense — it wears, it settles, and replacing it restores what the suspension was designed to do. Rate is the variable that depends on the rider, not on the machine. Two people on the same bike may well want two different numbers.
Fitting
Both legs are done together, and both take the same rate. The springs come powder-coated and need no preparation before they go in. The fork legs come off, the springs are swapped and the oil level is reset — half a day in most workshops.
Road Approval
Road approval: a spring is a like-for-like replacement of a wear part and carries no separate type approval. Where Öhlins states an approval for a particular motorcycle, it is named under Applications.
Fitting and Setup Service
We are an authorised Öhlins service centre, so the installation does not have to be your problem: we fit and set up Öhlins components in our own workshop. Ask us when you order and we will include the work.
Specifications
- Brand: Öhlins
- Part Number: 66388-01
- Spring Rate: 71 N/mm
- Free Length: 115 mm
- Inner Diameter: 55 mm
- Stroke: 71 mm
- Construction: Tapered
- Finish: Powder-coated black
- Country of Origin: Sweden
FitmentWhich bikes this fits▼
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