Product Overview


SDG I-Beam Formula FX £79.95

Weight: 225g / Colours: black, grey embossed pin-stripe, black, red embossed pin-stripe, white, grey embossed pin-stripe
Contact: Silverfish 01752 843882

We’re testing this saddle and seatpost together because you can’t use one without the other. The I-Beam technology means the saddle doesn’t have conventional steel rails but rather a reinforced mono-rail. Set-up is pretty similar to a conventional saddle and there’s a full range of fore, aft and tilt adjustment.
On this new Formula FX, the mono-rail has been shortened and lowered in relation to the base, which means in theory reduced side-to-side flex, which we didn’t like on the older
I-Beam saddles. It also gets a steel reinforcing plate, which adds weight but increases stiffness.
We like the shape of most SDG saddles, just because they feel pretty neutral, and the new Formula FX is no different. It has a flatter top than most saddles, and feels wider, so you don’t get that pressure ridge when grinding steep climbs. It also splays out at the back so that when you’re hunkering back there’s something to push against.
Most SDG saddles are cheaper than the FX but it is better made, with neater stapling, a DuPont nylon fibre composite base and a better quality leather cover. It’s still good value, but SDG is straying into Fizik territory, and even aping the Italian firm with its ‘D2 side density’ flexible panels.
Finally, if you’ve been put off I-Beam saddles because lack of rails meant you couldn’t fit a seatpack, don’t worry. SDG fits a Topeak QR System Bag Mount to the FX, allowing you to fit any of the Topeak seatpack range.