Bicycle frames are stiff truss structures with
little vertical compliance. As we've seen in my recent video about frame comfort, the majority of
the vertical deflection at the back of the bike is actually found at the rear tyre, seatpost and
saddle. Today, we'll be diving into the world of seatposts, and more specifically, suspension
seatposts. Given that cyclists often have 60 to 70% of their body weight on their saddle, I
don't know if there is any other component that offers as much of an improvement in ride comfort
- that's assuming you've already optimized your tyre width and pressure. The best bit is that a
suspension seatpost upgrade is as little as $100, and it's very easy to install yourself. Here
are my six reasons to use a suspension seatpost. #1 You can improve your comfort. A suspension
seatpost both absorbs bigger hits. as well as damping vibrations coming up from the road. The
less strain your body experiences when you ride, the fresher you'll feel at the end of the day.
#2 You can stay seated for longer. Suspension seatposts allow you to pedal while seated on
terrain that normally requires standing up. Compared to a rigid post on the same bumpy
climb, I find that my legs often feel fresher with the suspension seatpost simply because I'm
standing up less. #3 You can reduce or alleviate lower back pain. It's not uncommon to hear people
with back injuries say they couldn't ride a bike without a suspension seatpost. By isolating
vibrations and bigger hits from your body, you will put less strain on your lower back when
you ride. #4 They make narrow tyre bikes much more capable. A suspension seatpost allows you to take
bikes with narrower tyres on rougher terrain than you normally could. Obviously, this isn't an ideal
situation, but you'd be surprised how off-road you can go on 38mm tires. #5 The performance is
not height or weight dependent. The comfort of a regular seatpost is dependent on your body weight,
as well as the amount of exposed seatpost sticking out of your frame. As smaller riders often have
less body weight and less exposed seatpost, they have the most to gain with a suspension
seatpost upgrade. #6 They are lighter, cheaper and more simple than a full suspension
bike. Rather than using a full-suspension bike, you can fit a suspension seatpost to a hardtail
and enjoy similar levels of comfort, without the extra weight, price and complexity. Here are four
reasons NOT to use a suspension seatpost. #1 The weight. You can expect a 100 to 500-gram weight
penalty over a conventional aluminium seatpost. #2 The suspension bob. When you pedal, your body
movements create forces that can activate the suspension. This bob will occur to varying degrees
depending on the seatpost model and setup. #3 You have a full-suspension bike. If your bike has
rear suspension, your saddle is already suspended, so you do not need a suspension seatpost. #4
You have a fat bike. If you're riding a bike with four to five-inch wide tires those tires
are likely deflecting 30 to 60mm over bumps, which means that the benefits of a suspension
seatpost are significantly reduced. With the pros and cons out of the way, let's closely examine
the role of suspension seatposts. There are two things they're looking to achieve: a larger amount
of vertical deflection (which takes the edge off bigger hits), and a higher level of damping (which
increases vibration absorption). 'Deflection' is the total movement that a seatpost will move after
an impact. A seatpost with more deflection will reduce the fatigue on your body, as it protects
you from harder jolts like unexpected potholes or dirt road corrugations. It'll also allow you to
keep pedalling through particularly bumpy terrain. 'Damping' is the speed at which the seatpost will
move over repeated bumps. A seatpost that dampens vibrations effectively will help to insulate
you from road buzz coming up through your bike. High exposure to vibrations can actually increase
the risk of various injuries. including lower back pain and spinal degeneration. This is
why vibration exposure is often regulated in industries that require driving or operating heavy
machinery. When we measure seatpost vibrations in a laboratory setting, we find that some seatposts
can absorb 15x more vibration than others. For example. the Thomson Elite seatpost was tested
by Microbac Laboratories to absorb just .025 gs of vibrations while the Ergon CF3 was absorbing 0.375
gs. But interestingly, data recently collected by the University of Exeter suggests that once a
seatpost is installed on your bike, it may not reduce vibration exposure. That said, this test
was conducted using rigid carbon and aluminium seatposts, so it'd be interesting to find out
whether suspension seatposts are more effective using the same test protocol. Let's now take
a closer look at the different damping systems of suspension seatposts. First, we have spring
damping. The best way I can describe these seatposts is that they're very springy!
This makes them exceptional on off-road terrain as they're super-responsive to bumps.
But there is a cost to this high reactivity: I've found that when spring posts are perfectly
set up for rough terrain, they bob more than I'd like on smooth surfaces. The easiest way to
reduce this movement is to adjust the spring preload (or the amount of force required to cause
the saddle to start moving). This will stop the saddle bob, but will also reduce the seatpost's
ability to take the edge off small bumps. If smooth roads are your thing, you'll likely find
spring seatposts a bit too active. This brings me to elastomers. Elastomers are the quiet achievers,
as they're much less noticeable underneath you. This is the result of elastomers having an
inherently slower rebound speed after an impact, which is particularly beneficial while riding on
fast bumpy surfaces like gravel roads. I tend to prefer the more muted feel of an elastomer post it
feels more 'natural', for lack of a better word. The downside to elastomers is that they can
firm up in cold conditions, rendering them less effective, so skip this design if you need
it to work well in sub-zero conditions. I've also found they require lubrication around the edges
of the elastomer, although this maintenance is essentially solved with a simple seatpost cover.
Lastly, we have air damping, which is sometimes used in telescopic seatposts. The main advantage
is that you can adjust the spring rate to a higher degree of accuracy. Now, let's look at the
two different suspension seatpost designs. Linkage-driven suspension seatposts move in the
same direction as the forces coming up from the rear wheel. This allows them to very effectively
counteract, and even neutralize bumps, reducing the impact forces travelling through your back
and bum. In addition, linkage posts ensure that the saddle-to-pedal distance is mostly maintained.
When the seatpost is compressed, a telescopic post is usually considered inferior, as the angle it
compresses is different to the direction of force coming from the rear wheel, resulting in a less
reactive seatpost system. Telescopic posts also end up with a shorter saddle-to-pedal distance
when you are riding over bumps. Despite their flaws, telescopic posts are still very common, as
they're often lighter cheaper, more subtle, and have a lower installation height. Let's move on
to the data. To see how these different seatpost designs compare, Krzysztof over at GravelBikes.cc
has been using his smartphone with a vibration meter app to compare the vibration absorption of
different bike components, on both a rough trail and a fast gravel road. On the rough trail, the
spring seatposts are, by a large margin, the most effective at mitigating vibrations. Meanwhile, the
elastomer Cane Creek eeSilk offers around half as much vibration improvement. However, it's worth
noting that this seatpost only has around half the suspension travel. It'd be interesting to see how
a longer travel elastomer seatpost compares here. And finally, the air seatpost improved things
a bit, but clearly requires a higher bump force to activate. The gravel road with fast repetitive
bumps narrows the difference between an elastomer seatpost and a spring seatpost - despite
the variation in suspension travel. This is because the bump force is lower on gravel roads,
which means that the spring post is likely only using half its travel anyway. The air seatpost
showed little difference from the typical carbon seat post in this test. Suspension seatposts are
available with anything from 20 to 90mm of travel, so how do you choose the best travel for you?
Rougher roads warrant more suspension travel. As we just saw in the test, if you're riding
on rougher terrain with larger forces coming from the rear wheel, you will benefit from
more suspension travel as it can dampen more vibrations. I'd say most rough roads can
be comfortably cycled with just 35mm of travel, but 50mm or more may be required if you're
hitting bumps at higher speeds. More upright riding positions are also better suited to
longer suspension travel. This is simply due to the higher percentage of weight on your saddle.
Conversely, if you have more weight on your hands because you ride in a more sporty position - you
can get away with less suspension travel. Finally, let's now take a look at the best suspension
seatpost products. The Kinekt 2.1 and 3.1 are among the most active seatposts on this list,
offering 35mm of travel. There are five spring rates to choose from, suiting riders right up to
145 kilograms. The carbon model is the lightest coil-sprung seatpost money can buy at 471 grams.
These seat posts are particularly active in their initial part of their travel, so they tend to
be better suited on rougher trails rather than smoother roads, in my experience. That said, you
can quickly firm things up without using any tools via the preload control knob, which is an optional
extra for $16. The Redshift Shockstop is the best coil-sprung post I've tested, as it seems to do
a great job of absorbing off-road bumps without bobbing too much on the smoother roads. However,
it still isn't perfect. When I got the preload right for off-road terrain, I found there was
more bob than I'd like on the road. Unfortunately, the preload bolt is not particularly accessible as
it's at the bottom of the seatpost, so it's not an adjustment that you'd want to make too regularly.
The Shockstop weighs 547 grams and can be used by riders up to 110 kilograms. The By.Schulz G.2
is a very highly-rated seatpost. There is a short-travel version with 30mm and a long-travel
version with 50mm of suspension. You can choose from five different spring rates, which will suit
riders all the way up to 150 kilograms. There are 10 different diameters too, making them suitable
for almost every bike. The downside to this seatpost is that there is no preload adjuster,
so you might find it feeling springy sometimes, and it's heavier than most at 700 grams or
so. The low-cost suspension post of choice is the Suntour NCX. At under a hundred dollars,
it's a complete bargain, but there are downsides: it's pretty heavy (around 800 grams) and it
comes with only one spring rate out of the box (although softer and firmer springs are only $15).
The maximum rider weight is 120 kilograms. I've spent years on the previous version of the Cane
Creek Thudbuster. With its slower rebound speed, I think it's a great option if you ride a larger
percentage on smoother surfaces. The 50mm of travel is ample for off-road use too. There are
four spring rates to choose from, suiting riders right up to 150 kilograms. If you ride a mix of
gravel and tarmac roads I don't know if you can do any better than the Cane Creek eeSilk. At half the
weight and half the travel of most squishy posts, it performs closer to the best carbon seatposts
available. But the key difference to a carbon post is that the spring rate isn't determined by
how much exposed seat post you have, allowing you to perfectly tune it to your body weight using
the five different elastomers available. Regular dropper posts have very little vertical flex,
which is an unfortunate consequence of their telescoping design. If you love dropper posts, but
also want to maximize your ride comfort - there are two suspension options available (and a third
in the works). The best performing model is the Byschulz D.2. It costs a small fortune, but this
coil-sprung option will stay incredibly active on bumpy roads. Like the regular Byschulz post, there
are multiple spring rates to choose from and 30mm of travel. The other dropper option is the PNW
Coast, which has 40mm of suspension, and is the best-value dropper by far. This air spring system
has been tested by gravel bikes to be much less active than the other suspension seatposts, but
it'll still take the edge off those bigger hits, and performs well on gravel roads too. In summary,
a suspension seat post is a great comfort upgrade as it will both absorb bigger hits as well as
dampen vibrations coming up from the road. This essentially means you'll feel fresher at the end
of a long ride. For anything slow and off-road, you cannot beat a spring-damped seatpost. These
posts are incredibly active underneath you, and will allow you to stay seated on rough surfaces
for much longer. If you ride a decent percentage on smoother surfaces or are sensitive to
suspension bob, you'll prefer elastomer seatposts, as they're less noticeable underneath you. The
Cane Creek eeSilk is what I personally use and recommend. It's great for if you have a sporty
ride position like me, or if you mostly ride on smoother roads. Given it only has 20mm of travel,
you will have to compromise on the rougher roads, but I still find it offers a significant comfort
improvement over a regular post. Plus it doesn't bounce, it's light and it's elegant. If this video
has inspired you to pick up a suspension seatpost, check out the affiliate links below, which
will help to support this channel. You can also support my bike nerd content directly on
Patreon or via Paypal. Alternatively, grab a copy of my Touring or Bikepacking Bike Buyer's Guides,
which will teach you everything you need to know about the bikes, before allowing you to compare
hundreds of current bikes at the back of the book.
