{"product_id":"ohlins-shock-spring-90-n-mm-160-mm-51-mm-21040-29","title":"Öhlins Shock Spring 90 N\/mm \/ 160 mm \/ Ø 51 mm – 21040-29","description":"\u003cp\u003eÖhlins part number 21040-29 is a shock absorber spring rated at 90 N\/mm, 160 mm long with a 51 mm inner diameter. Adding a pillion or luggage changes the load enough that the standard rate stops working.\u003c\/p\u003e\u003ch2\u003eKey Features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eMeasured spring rate 90 N\/mm\u003c\/li\u003e\n\u003cli\u003eFree length 160 mm\u003c\/li\u003e\n\u003cli\u003eÖhlins part number 21040-29\u003c\/li\u003e\n\u003cli\u003eStraight-wound, constant rate\u003c\/li\u003e\n\u003cli\u003e78 mm of usable stroke\u003c\/li\u003e\n\u003cli\u003ePowder-coated yellow\u003c\/li\u003e\n\u003cli\u003eInner diameter 51 mm\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eManufacture and Tolerance\u003c\/h2\u003e\u003cp\u003eTwo units carrying the same part number behave the same way out of the box, which is the whole point of testing each one. Every Öhlins dealer can re-valve the unit, because the shim stack is a documented, serviceable assembly. Rates are offered in defined steps, so a change can be made in one direction at a time.\u003c\/p\u003e\u003ch2\u003eThe Numbers That Matter\u003c\/h2\u003e\u003cp\u003eAt 160 mm free length and 51 mm inner diameter, this spring is dimensionally interchangeable with anything of the same size — the rate is what makes it a different part.\u003c\/p\u003e\u003ch2\u003eChoosing 90 N\/mm\u003c\/h2\u003e\u003cp\u003eIf the suspension bottoms out or the geometry collapses under load, this is the direction to go. Support under braking improves; small-bump comfort gives a little back. Firm rates trade some small-bump comfort for support — the right trade on a good surface at speed. 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.\u003c\/p\u003e\u003ch2\u003eHow a Rear Spring Works\u003c\/h2\u003e\u003cp\u003eRear 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. A spring that has settled in service sits shorter than new, which quietly lowers the bike and steepens the steering. Two riders 20 kg apart on the same motorcycle genuinely need different rates, not different clicks.\u003c\/p\u003e\u003ch2\u003eApplications\u003c\/h2\u003e\u003cp\u003eWhere Öhlins lists this size against a particular unit, the listing is a starting point rather than a boundary. Selection is by measurement. If the diameter and free length match your fork, the remaining question is the rate. There is no model list for this size because the spring is a dimensional part: it fits whatever fork it physically fits.\u003c\/p\u003e\u003ch2\u003eFitting\u003c\/h2\u003e\u003cp\u003eFork oil should be replaced at the same time — it is already out of the leg. Fitting is a fork-oil job: the legs come apart, the springs go in, the oil level is set to specification. Set static sag after fitting; the rate is only right if the sag figure lands where Öhlins specifies.\u003c\/p\u003e\u003ch2\u003eRoad Approval\u003c\/h2\u003e\u003cp\u003eRoad approval: none is issued for springs as such — they replace an existing component of the same function. Any model-specific approval is listed under Applications.\u003c\/p\u003e\u003ch2\u003eFitting and Setup Service\u003c\/h2\u003e\u003cp\u003eThis is not a part to rush. Öhlins recommends installation by an authorised service centre, and we are an authorised Öhlins service centre — fitting, servicing and setup all happen here. Get in touch if you would like the work done with the order.\u003c\/p\u003e\u003ch2\u003eSpecifications\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cem\u003eBrand:\u003c\/em\u003e Öhlins\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003ePart Number:\u003c\/em\u003e 21040-29\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eSpring Rate:\u003c\/em\u003e 90 N\/mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eFree Length:\u003c\/em\u003e 160 mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eInner Diameter:\u003c\/em\u003e 51 mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eStroke:\u003c\/em\u003e 78 mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eConstruction:\u003c\/em\u003e Straight\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eFinish:\u003c\/em\u003e Powder-coated yellow\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eCountry of Origin:\u003c\/em\u003e Sweden\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Öhlins","offers":[{"title":"Default Title","offer_id":53645403259146,"sku":"21040-29","price":6000.0,"currency_code":"PHP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0949\/7831\/0410\/files\/RearOhlinsSpring_ad72b2fe-9a22-4c7d-85ef-5e63e456b815.png?v=1788866843","url":"https:\/\/inter-pace.com\/en-ph\/products\/ohlins-shock-spring-90-n-mm-160-mm-51-mm-21040-29","provider":"Inter-Pace","version":"1.0","type":"link"}