Dahon Seatpost Diameter: The K9 Table and the 34 mm Pump Label
Dahon seatpost diameter should come from the relevant component specification, rather than a nearby accessory name. The current USA K9 table lists its JB-SP-321JC post as 33.9 × 580 mm. The same page recommends an integrated seatpost pump labelled 34 mm, but that label does not rewrite the post's detailed entry.
Locate Dahon seatpost diameter in the actual table
The K9 row combines a part name with a diameter and overall length. Retain all three when asking about a replacement. Calling it a 580 mm post without its diameter leaves the request incomplete; rounding the diameter because an accessory heading uses another number creates a different request.
This distinction is about reading the page accurately, not declaring the recommended accessory incompatible. The manufacturer may provide a suitable accessory, but a recommendation tile alone does not explain its dimensional notation or approve every similarly labelled product from another supplier.
Compare the K3 and Boardwalk entries selectively
The current K3 table names the same JB-SP-321JC, 33.9 × 580 mm. That is a shared published component reference for the two named USA models. It is not proof that every older K3 or K9, or every post carrying a nearby measurement, has the same complete installation requirements.
Boardwalk D7 16-inch instead lists JB-SP-314 and 530 mm. Its selected post row supplies no diameter. The 530 mm entry therefore cannot be treated as an alternative diameter, nor should the missing figure be filled from the K9 simply because both are DAHON folders.
Establish the saddle position the replacement must achieve
The generic owner's manual currently linked by DAHON bears a 2012 copyright notice. On page 7 it warns against extending a seatpost beyond its insertion marks and calls for a securely fixed saddle. It does not supply a new K9-specific insertion depth or an instruction to use all 580 mm outside the frame.
Describe the desired saddle position and ask the supplier to establish the appropriate post and permitted installation on the identified bicycle. This guide offers no shim, lubricant or tightening recipe; the dimensional table alone cannot select those procedures.
Keep the listing and photograph in their proper roles
BestBicycle lists this model as Dahon K9 Bike — Silver-4-Bearing. That provides the K9 reference for the enquiry. The long post is visible on the exhibition bicycle, but the photograph does not measure its diameter, show a readable insertion mark or verify the current supplied component. Use the actual bicycle and the applicable instructions to complete the decision.
FAQ
Does the K9 table say 34 mm?
No. Its post row gives 33.9 × 580 mm; 34 mm appears in an accessory label.
Is the Boardwalk 530 mm figure its diameter?
No. The selected entry provides a post length without specifying its diameter.
Can the picture establish safe extension?
No. The relevant marks and instructions must be checked on the actual assembly.
Unsure whether the bicycle is a K3 or another DAHON family? The range background is a useful starting point before returning to the Dahon directory and identifying the actual model.
Manufacturer references checked 3 November 2026: k9 (https://usa.dahon.com/products/k9), k3 (https://usa.dahon.com/products/k3), boardwalk16 (https://usa.dahon.com/products/boardwalk-d7-16), owners manual (https://cdn.shopify.com/s/files/1/0701/1637/6877/files/English-Owners-Manual.pdf?v=1676239121).
Photograph credits and permissions
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Original title: Dahon K9, Eurobike 2025, Frankfurt am Main (P1048231).jpg
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