I’ll touch upon the importance of this later, but for now it is worth noting that the pinch-bolt merely keeps the seatmast topper attached to the frame. The seatmast topper fits slides down over the ISP and then tightens with a pinch-bolt. These bikes feature an aero-shaped seat tube extension that takes a proprietary seatmast topper.
#Trek bike seat series#
Giant was one of the first to widely market a production road bike with a true ISP with a development of their TCR series of carbon road frames. But this type of design is generally not considered to be an ISP, probably because there’s nothing all that proprietary about the design. From a fabrication perspective, using a round inner diameter tube to hold a conventional seatpost is orders of magnitude easier than creating a piece that would match either the inside of outside contour of the aero-shaped seat tube. Looking closely at the picture, you can see that there is a round tube (to actually hold a stub conventional seatpost) grafted into the top of extended aero-shaped seat tube. A past example, though far from a the earliest such, is the Bianchi Crono titanium TT bike from the 1996 TdF, often called the “Berzin” bike after the high-profile Russian rider Evgeni Berzin using it that year.
#Trek bike seat trial#
This was most commonly seen in one-off time trial bikes, which have often been the canvas for builders to show off their flare or innovation. It is neither a stretch of the imagination nor technically difficult to make a metal frame with an exaggerated seat tube extension that then takes a highly abbreviated seatpost. Okay…so Giant created the ISP, right? Well, it’s not so easy as that, because arguably there have been many examples by small custom builders dating back decades ago. In fact, Ritchey and Giant offer alternate tall toppers that give an additional 50mm (+20mm adjustment), so it’s not like no one could ever make use of your ISP bike after you. To an extent, this issue is over emphasized by ISP critics most mast toppers still allow 20mm of vertical adjustment. Since the seatmast must be cut, typically by hacksaw with a guide, fitting the ISP bike to a specific rider means permanently modifying the bike, much like cutting down a threadless steerer will limit stem/handlebar vertical adjustment. In addition to fore-aft/tilt of the seat clamp like conventional seatpost, a seatmast topper frequently allows for some measure of vertical seat adjustment on the ISP, which must otherwise be trimmed to a specific height. I’m going to refer to the piece that attaches the saddle to the “integrated seat tube” (or “seat mast”) as a seatmast topper, which is actually Ritchey Design’s term for their product that several bicycle manufacturers, Scott among them, use for their own ISP frames. ISP: marketing, weight, structural, practicalįirst of all, “ISP” appears to be a Giant Bicycles product name, but since it’s convenient I’m going to appropriate the term for this article. What does an ISP offer? Is it the wave of the future? What should you know before you buy one? Instead, these frame designs have seat tube structures that extend far beyond the top of the top tube and incorporate some sort of specific fitting to hold the saddle atop.
![trek bike seat trek bike seat](https://www.twowheelingtots.com/wp-content/uploads/2020/05/Burley-Dash-Child-Bike-Seat-Review-1024x683.jpg)
Integrated seatpost, integrated seat mast, ISP…in the past few years there have been a number of different frame designs on the market that eschew a traditional, round/cylindrical seatpost that inserts into a seat tube.