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…
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.
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.
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.
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.
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.
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.
