{"product_id":"ohlins-piston-8-25-bleed-2x1-4-21800-01","title":"Öhlins Piston 8\/25 bleed 2x1.4 – 21800-01","description":"\u003cp\u003ePiston 8\/25 bleed 2x1.4, Öhlins part number 21800-01. A worn piston band lets oil past the outside of the piston, which shows up as damping that has gone soft.\u003c\/p\u003e\u003ch2\u003eKey Features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eDimension A 8 mm\u003c\/li\u003e\n\u003cli\u003eDimension B 25 mm\u003c\/li\u003e\n\u003cli\u003eOriginal Öhlins service part\u003c\/li\u003e\n\u003cli\u003eÖhlins part number 21800-01\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFunction\u003c\/h2\u003e\u003cp\u003e8 mm, 25 mm: that is the whole specification, and it has to match what came out. The piston carries the shim stacks and meters the oil; its port layout is what makes an Öhlins damper behave the way it does. Twin-tube pistons have separate paths for compression and rebound, which is the whole point of the design. Replacing a piston is a workshop job because the shim stack has to be rebuilt in the correct order.\u003c\/p\u003e\u003ch2\u003eWhy the Original\u003c\/h2\u003e\u003cp\u003eÖhlins manufactures service parts on the same lines as production parts — there is no second quality. Buying the individual part rather than a complete assembly is what makes servicing an Öhlins unit worthwhile. Order by part number. The dimensions below are the ones Öhlins publishes for it. If you are unsure which number your unit takes, send us the model and serial number of the damper and we will look it up.\u003c\/p\u003e\u003ch2\u003eHow to Be Sure It Fits\u003c\/h2\u003e\u003cp\u003e21800-01 is the Öhlins number for this position — the same one printed in the service documentation. The published dimensions are dimension a 8 mm, dimension b 25 mm — measure the old part against them if you are unsure. Needle geometry sets the shape of the adjustable range, not just its size. A check valve holds pressure in one direction and opens in the other; a worn one lets damping bleed away.\u003c\/p\u003e\u003ch2\u003eFitting and Setup Service\u003c\/h2\u003e\u003cp\u003eA damper rebuild is workshop work: it needs the unit dismantled, the shim stack rebuilt in the correct order and the gas charge reset. We are an authorised Öhlins service centre and do exactly that in house — send us the unit or ask us to fit the part with your 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 21800-01\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eCategory:\u003c\/em\u003e Pistons\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eDimension A:\u003c\/em\u003e 8 mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eDimension B:\u003c\/em\u003e 25 mm\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":53651663356170,"sku":"21800-01","price":75.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0949\/7831\/0410\/files\/21800-01_df025e41-7b43-4823-a8ee-884e0e49c9c1.png?v=1788877818","url":"https:\/\/inter-pace.com\/en-pa\/products\/ohlins-piston-8-25-bleed-2x1-4-21800-01","provider":"Inter-Pace","version":"1.0","type":"link"}