Adding a suspension seatpost to your eBike is one of the easiest upgrades you can make, a straightforward task that most home mechanics can handle. Here's what you need to know to choose a suspension seatpost and install it on your eBike, including recommended makes/models and step-by-step installation instructions.
Why use a suspension seatpost
If you're riding a "hardtail" eBike (one that has a front suspension fork, but no rear suspension built into the frame) or even a full rigid eBike with no suspension at all, a suspension seatpost is an economical way to take the edge off bumps, allowing you to ride with more comfort and control.
Suspension seatposts have a plunger (similar to the way a suspension fork works) or parallelogram design, both of which allow the eBike's saddle to move up and down in response to rough terrain or bumps. Higher-end models have adjustable spring preload to suit different rider weights and riding styles.
Installing a suspension seatpost is much less expensive than the cost of a full-suspension eBike frame - which can add hundreds of dollars to the cost of an eBike. Suspension seatposts, on the other hand, cost just $50 - $300.
Get the right length and diameter seatpost
We need a couple measurements to get the right size replacement seatpost. They come in various lengths and diameters. While there is some flexibility around the length to suit your personal preference, the diameter must match your existing seatpost exactly.
If you remove your existing seatpost, you'll often find the measurements stamped right on it, near the minimum insertion mark. For example, you might find a seatpost marked "27.2mm x 400mm" - that's a post with a diameter of 27.2mm and a length (measured from the end of the "pipe" to the saddle rails) of 400mm. Occasionally, the markings are less clear - you might find a seatpost marked "316" - that's shorthand for 31.6mm, and so on.
If you can't read the markings on your existing seatpost, you may to to measure manually. This must be very precise, so consider using a digital caliper. You an also check with the manufacturer of your bike to see if they have the right size on file to save you the trouble.
Generally, you should purchase a replacement seatpost of the same overall length, or close to it, as the model it replaces. Too short, and you may not be able to raise the saddle high enough, too long, and you may not be able to lower it enough to suit the rider.
It's important to keep in mind that adding a suspension seatpost can limit how low the saddle can be - that's because the round, pipe-shaped portion of the seatpost has to slide into the frame, and the moving portions on the new suspension seatpost must be exposed, externally, outside the bicycle frame. It's common for the minimum saddle height to go up by a couple inches when you upgrade to a suspension seatpost, so take a note of this if your existing saddle height is already close to as low as it can go.
Using a seatpost shim
Sometimes you may find that your preferred seatpost doesn't come in a diameter that exactly matches your eBike. In that case, you can sometimes use a shim to adapt the two.
For example, 27.2mm is a very common size for suspension seatposts, but many eBike frames are designed for 30.4mm diameter seatposts. A 1.6mm shim on either side adds a total of 3.2mm, and 27.2mm + 3.2mm = 30.4mm - the exact size we need!
It's best to use the exact size when it's available, but if not, a shim can be an economical fix. Problem Solvers is a popular brand of seatpost shims available in many different diameters you can use for this purpose.
How to install a suspension seatpost
- You may wish to measure and mark your existing saddle height before you begin, so you can quickly return to the same saddle height later.
- Remove the old seatpost from the bike (with the saddle still attached) by either opening the seatpost clamp quick release, or loosening the hex bolt on the seatpost clamp.
- Make a note of the length and diameter (usually stamped near the minimum insertion mark) and purchase the right size replacement
- Remove the saddle from the old seatpost by loosening the fixing clamp that holds the seatpost and saddle together.
- Install the existing saddle on top of the new seatpost, but don't fully tighten yet.
- Apply grease or anti-seize to the seatpost shaft in accordance with the manufacturer's instructions. Different material seatposts and frames may have different instructions.
- Slide the new seatpost into place and close the quick release lever (or tighten the hex bolt) to hold the height in place.
- Set the saddle to the desired angle, and tighten the clamp to hold it in place.
- Take a quick test ride, then make final adjustments to saddle height and angle.
Popular makes and models of suspension seatposts
Basic short-travel suspension seatposts start at about $50, while long-travel models made of lighter materials with more range of adjustment sell for about $300.
At the high end, one of the most popular suspension seatposts of all time is the Cane Creek Thudbuster, for about $150. This model uses a parallelogram design and elastomer bumper, which can be changed out to suit different rider weights. It comes in long travel (for off-road use) and short travel (for mostly paved surfaces) versions.
Suntour's NCX is a more economical model (about $120) that is very popular with eBike riders. Redshift's ShockStop is another popular model that splits the difference between the Cane Creek and Suntour products.
Cane Creek also makes the eeSilk, a model focused on weight saving for about $300. While the functionality is similar, the fancier models are a nice upgrade that helps control the weight of your eBike.
What you get for your money
More expensive, higher-quality suspension seatposts have some features that less expensive styles lack:
- They'll be lighter. It's nice to control the weight of your eBike, especially if you lift it on and off a car rack, or carry it up stairs.
- They offer more adjustment range to suit different rider weights
- They can have longer travel (i.e. they can absorb bigger bumps) than basic models.
The team at Bike.com can help you select and install a suspension seatpost on your favorite eBike. Reach out anytime for assistance.