If you’re trying to smooth out your bike’s ride quality, then you’ve probably come across sprung saddles & suspension seatposts.
Both are effective ways to take the edge off of bumps, but they do so in slightly different ways that will delight some riders and frustrate others.
Suspension seatposts are more versatile because they absorb more bumps, can be fine-tuned, and work with all riding positions. However, they affect saddle height and therefore leg extension while riding. Sprung saddles don’t affect seat height, but they don’t absorb as many bumps and are only useful with upright riding posture. Neither are popular among competitive cyclists.
Both will add roughly $50-$150 and 0.5-1.5 pounds to your bike, depending on what parts you’re starting with.
Before we dive deeper, it’s important to understand three things:
- Both are far less effective than full suspension, which typically has 4″+ of travel compared to about 2″ for a seatpost and well under 1″ for a saddle. However, full suspension is overkill for anything except rugged mountain biking, and it must be built into the frame to begin with.
- Wider tires (at appropriate pressure) will absorb more bumps and improve traction. Consider installing the widest tires your bike can accommodate before changing your seatpost or saddle.
- Competitive cyclists and dedicated hobbyists rarely (if ever) use either one. Sprung saddles are inappropriate for the forward-leaning posture that competitive cycling demands. Suspension seatposts add weight and cause bike-fitting problems for road cyclists; they also preclude dropper posts which most mountain bikers prefer today.
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How suspension seatposts work
Most modern suspension seatpost have two parts: a main tube (that inserts into the frame) and a narrower, telescoping portion that the saddle attaches to. The telescoping portion slides inside the main portion and is suspended by a metal spring and/or an elastomer block.
Here’s a popular entry-level example of the telescoping design:
A second and also very common style replaces the telescoping portion with a hinge that looks like a parallelogram. In the middle of the parallelogram is a small elastomer; the rider’s weight and/or bumps in the ground compress the elastomer and thereby move the hinge. This style moves diagonally—not perfectly vertically like a telescoping design.
Here’s a high-end model that uses the parallelogram style:
Both types commonly have a screw to preload (compress) the spring or elastomer. Tightening the screw increases preload and therefore makes the suspension firmer. This is an important way to dial in the seatpost to your weight and terrain. The preload range is limited, though, so some manufacturers offer different springs/elastomers to suit different rider weights.
Quick tips for suspension seatpost adjustment
One nice thing about adjustable preload is that you can set up “sag,” meaning the seatpost compresses just slightly under your weight. That gives it room to compress and extend, so it feels less like a pogo stick when you roll over depression in the ground.
Start with sag of around 25% of the suspension travel (e.g., 1/2″ on a post with 2″ travel) and adjust from there. However, the seatpost should also be firm enough to avoid bouncing (“bobbing”) as your weight shifts while pedaling.
How sprung saddles work
Sprung saddles use metal springs and/or elastomer blocks inside the rear portion of the saddle. These absorb some of the impact of a bump rather than passing all of it along to the rider.
Generally, the springs are only in the rear of the saddle, so they’re only suited to upright posture. (In more aggressive or forward-leaning posture, your arms support so much weight that it’s not easy to activate saddle springs.)
The springs can usually travel just a fraction of an inch, and virtually never have adjustable tension, so they can’t match the shock absorption or adjustability of suspension seatposts.
On one hand, it’s nice not to have any adjustments to fiddle with or fine-tune. On the other hand, very light or very heavy riders may have a tough time finding the right amount of firmness.
Very rarely, you’ll find one with both front and rear springs. The Brooks B33 is the best-known example—and perhaps the only one that’s widely available—but front springs aren’t effective enough to justify the enormous added weight.
These leather saddles are very firm and even a bit uncomfortable until they break in after several hours of use. However, I strongly recommend them over the squishier kind you’ll often see. They feel pleasant for the first few minutes but may cause saddle pain as they compress nerves and soft tissue. For example, I would categorically avoid sprung saddles like the following for rides longer than 10-20 minutes.
Which is best for you?
Neither is categorically better than the other.
I generally recommend a sprung saddle for anyone who rides with upright posture on mostly paved terrain. They are simpler to set up, require no special maintenance, and are a nice complement to the wide, soft tires that most upright bikes have.
Conversely, a suspension seatpost is better for a hybrid, mountain, road, or any other bike with more forward-leaning posture. If you’re riding rough terrain, then you’ll benefit from the longer travel and greater adjustability. You’ll also be able to keep your existing saddle, which is especially helpful since sprung saddles almost never come in narrower widths that suit a forward posture.
Suspension seatposts are more adjustable
It’s best when suspension firmness is proportionate to your weight and terrain.
There’s essentially no adjustment on a sprung saddle, but it’s trivially easy (just turn on a screw!) on a suspension seatpost. That lets you dial it in for the smooth possible ride, all else being equal.
Sprung saddle options are limited
Suspension seatposts are basically universal. They won’t have as many diameter and length options as standard seatposts, but all the common ones are readily available and will work with any modern saddle.
Conversely, almost all sprung saddles use a wide shape that’s meant for a very upright riding position. That’s ideal for most city, cruiser, and comfort bikes, but it’s a problem for other styles that position you less upright. The Brooks Flyer—essentially a sprung B17—is one of the only choices for the latter.
Both add similar weight
Suspension seatposts and sprung saddles both add significant weight to your bicycle. The exact weight difference will depend on what saddle or post you started with, but about 300g or 10oz is a reasonable expectation.
The springs themselves explain some of the weight difference, as do the extra reinforcements and moving parts.
Suspension seatposts make saddle adjustment harder
In my experience, saddle height adjustment is the biggest and most frustrating problem with suspension seatposts.
Keeping your seat at the appropriate height is essential for riding efficiently. If it’s too high or too low, then you won’t achieve optimal leg extension during the pedal stroke, and you may even experience joint pain due to biomechanically incorrect movement.
Along those lines, note that suspension seatposts with a parallelogram design (vs. purely telescoping ones) move a bit diagonally as they compress. This subtly changes the reach to your handlebars, which may feel slightly disconcerting until you get used to it.
Sprung saddles usually compress less than an inch, and they don’t sag noticeably under an average rider’s weight. Consequently, they have no effect on seat height adjustment..