eightpins integrated dropper post inside seat tube

Teased just before Eurobike, the new Eightpins integrated dropper post looked to solve the problem of potential binding at the seat post collar with a unique solution. What it also brought to the table was longer and truly customizable travel options.

It requires the frame to be designed around the post (for now, anyways), bolting the bottom of the post into the bottom of the seat tube. It’s called the Postpin mount, and that’s almost the extent of non-standard modifications required. The inside diameter of the seat tube is 34.9mm, a standard that’s not as common as 27.2 or 30.9, but still a standard. Everything else fits inside, with the collar threaded into the seat tube rather than clamping around it…

eightpins integrated dropper post inside seat tube

Four sizes of post are available, letting them fit virtually any size frame. The smaller ones in particular bring about options for very small frames where traditional dropper posts don’t fit. Part of that solution is the packaging, but the other part is that you can customize the starting point and travel down to as little as 20mm. Max travel, by post size, is 150mm (S), 180mm (M), 200mm (L) and 220mm (XL), which can be set independently of saddle height. And it drops about 20mm lower than other posts because there’s no collar above the seat clamp…because there’s no seat clamp.

eightpins integrated dropper post inside seat tube

The post is made up of two cylinders. The thinner one sits on the bottom and bolts into the frame. The larger one, which is what slides up and down, goes over it. There’s a thin bushing between it and the frame, starting at the top of the seat tube and running deep down into the frame, deeper for the longer posts.

eightpins integrated dropper post inside seat tube

Post diameter is 33mm, meaning the bushing between it and the seat tube is very thin. That means a stiff, strong design, with Syntace’s proven post as the basis. The posts ship with full travel, but you can manually limit it to as little as 20mm. Or, for smaller frames, you can trim length off the bottom of the outer cylinder to gain travel. Basically, up until the max for each post size, travel is limited by either the saddle hitting the top of the seat tube, or the outer cylinder hitting the Postpin.

The post height is adjustable using an allen bolt under the saddle – so, yes, you’ll need to loosen the saddle clamp to access it, but they’ve made it so you don’t need to remove the saddle and lose all of its positioning to do so. That’s for the straight post. For the 23mm setback post shown here, you simply turn the dial at the top of the post.

The “collar” is there primarily to keep out dirt and moisture, using a standard wiper seal. The frame does need a hole for that small bolt to thread into, which is the only other modification needed to make this work on any frame.

eightpins integrated dropper post inside seat tube

The dropping action is light, letting you quickly get down and out of your way. Another way it differs is in how it holds itself. There’s no fluid, it’s a purely mechanical system using an air spring to return it to the top. The name Eightpins provides a clue as to how it works, with mechanical pins locking it into place. Travel feels smooth and infinite, but it actually has 6mm increments of pin holes that it catches into. The upside is that there’s nothing to leak, and in our “parking lot” tests, you can’t feel the increments since there’s no clicking or stepping as it goes down. It simply locks into place as soon as you let go of the lever – speaking of which, had a nice, ergonomic feel and easy actuation.

eightpins integrated dropper post inside seat tube

The upper cylinder has an overload clutch built in to let the saddle rotate in the event of a crash. This prevents damage to the post, and you can simply twist it back to straight afterward. The post itself won’t rotate because of the Postpin at the bottom.

eightpins integrated dropper post inside seat tube

Another upside to this design? It’s light. Weights range from 430g to 550g depending on size, making even the largest one comparable to current competitive dropper posts.

The design is exclusive to Syntace through 2017, after which any bicycle or component brand can license the Postpin design to integrate it into their frames.



    • Also Matt on

      That’s a great question. No article I’ve yet seen on this makes the case for why this is so much better that bike brands will incur the substantial cost to change their frame molds (if carbon) to accommodate the wider seat post. Especially when the big guys have committed significant resources to developing their own posts.

      • gee on

        It’s supposedly 175g lighter than a reverb, and allows for much more travel – up to and exceeding 200mm depending on seat tube length and the height of the rider (someone will comment soon that 100mm is enough for them)

  1. SoupaDuPa on

    Would be way cooler if it didn’t have the giant “8PIN” collar. They were close to pulling off a super clean design but fell short. Look at road headsets, you can barely see it anymore. Stems, bars, post, cables, brake are more integrated into the bike and it looks excellent. Since the bike industry has done away w/ compatibility, it might as well make components integrate and look elegant.

    It’s interesting to see the OEM bike brands driving mediocre sales in the industry while the stock market and housing keep going up. USA should be seeing excellent sales the last few years but we are not. All the new standards and non-compatibility have killed customer service at the dealer. Dealers have to order parts instead of stocking them. Distributors have to warehouse more inventory and consumers buy online at/below dealer pricing. A repair that would take 1 day now takes 2 weeks. Bike prices have doubled in the last decade and the technology arms race is having consumers avoid buying new bikes and keeping their current bike much longer. Why buy a bike having it non-compatible and outdated in one year. Inventory becomes outdated much faster now so more closeouts are driving prices down, further growing the online dealer direct sales at an alarming rate. Only rich or crazy people buy Shimano at a dealer when it’s way cheaper online. Additionally the industry is pushing hardtail plus bikes trying to take the place of FS bikes. A hardtail plus is a similar price as an entry level FS. To me I love the new hardtail plus bikes but your average person does not. They really want an FS bike, yet the industry is cramming expensive plus hardtails down everyone’s throats. Will be interesting to see what bike inventory looks like next summer when entry level FS models are sold out and there are mountains of plus hardtails everywhere at blow out prices. Marin is one of the few companies that sees this and has lots of non-plus hardtails and entry FS models. To me this is smart spec and inventory management for the current market.

    Sorry for the sideways rant.

    • Dominic on

      Every single point you made just makes me hate being associated with the cycling industry. Mostly to your own detriment. Seriously, first point: don’t you see the potential, visually for the collar as is? It doesn’t have any cables or bolts sticking out, so it is cleaner.
      There’s a new brand every week, a new custom builder a new catalogue brander, a new innovator, a new Taiwanese factory.
      I agree with you on the insane level of stocking to satisfy BB standards and crank-frame inter-compatibility. it’s absolutely mental. There’s hardly any point stocking anything in a shop anymore unless you’re huge or have an INFORMED niche clientele.
      What’s this about the industry pushing hardtail plus bikes? That a thing? Are they all running boost, or just some of them?

      @ Veganpotter, at 65 mm, what is the point of dropping the post? I don’t understand, honestly.

      • SoupaDuPa on

        Dominic, just saying the “large” logo doesn’t look good on the clean design. The design is great, stealthy but the huge logo detracts a lot. Sorry that was not clear.

        As for plus hardtails, they are all boost which is great since it’s been over do to stiffen the tall, wide wheels and improve gearing for large tires. It’s the push for plus hardtails by brands all at once w/ out consumers asking for it. It’s being pushed down their throats. The industry turned a basic hardtail (usually an entry level bike for new riders), into an overly expensive bike (more expensive: hubs, TA axles, TA forks, wide rims, wide tires and sometimes dropper post). All this adds up close to an entry level FS bike from 2 years ago. However even entry level FS bikes are going up in price because of the same reasons. Don’t get me wrong, all of this spec is a performance upgrade but it raises the price a lot. Just saying there will be lots of closeouts of nice hardtail plus bikes in the middle/end of summer next year.


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