This post compares the advantages and disadvantages of bikes using suspension seat posts and full-suspension MTBs.
The Advantages of Suspension Seatposts
Suspension seat posts allow the user to instantly add a form of rear suspension without buying a new bicycle.
A suspension seat post has to meet two requirements:
a. Sufficient length (the seat post should be capable of elevating the saddle as much as the rider needs)
b. Proper diameter – the diameter of the seat post should be slightly smaller or equal to that of the default seat post. If the seat post has a smaller diameter than needed, a shim will be needed for a secure fit.
Suspension seat posts are many times cheaper than upgrading to a full-suspension bike and thus make a lot of sense when the user wants some extra comfort without spending large sums of money.
- Compatibility With Commuting Accessories Designed for Rigid Bikes
A suspension seat post moves independently of the frame. Thus, the bike remains compatible with fenders and rear racks designed for rigid frames.
In different, full-suspension bikes are not compatible with the vast majority of rear fenders and rear racks because the rear triangle of the bike is not stiff.
Of course, one can still install such accessories on full suspension bikes, but the choice is limited, and the prices are high.
- Compatible With All Kinds of Bikes
99% of full-suspension bikes are MTBs. Thus, by going the full-suspension route, you will be stuck with a single bike type.
Meanwhile, a suspension seat post can be added to all kinds of bikes – road, gravel, commuting bicycles, single-speed models, folding bicycles…etc.
This makes suspension seat posts more versatile.
Full-suspension bikes are among the heaviest bicycles out there. Therefore, to enjoy the luxury of rear suspension, you will have to carry a pretty hefty beast everywhere you go.
A suspension seat post may be notably heavier than a rigid one, but it doesn’t add that many grams to the overall weight of the bike. If the bike is light, a suspension seat post will not make it heavy.
- Non-permanent Changes
If you don’t like the effect of a suspension seat post, you can remove it and install a rigid one in a couple of minutes. Then, you can return or re-sell the product. In other words, the commitment isn’t that high.
The Disadvantages of Suspension Seatposts
- Limited Travel
It’s important to understand that a suspension seat post does not provide nearly as much cushioning as a rear shock.
The travel is small and involves only the seat post. In the case of full-suspension bikes, the entire rear-end of the bicycle is suspended.
- No Effect on Rear Wheel Traction
The main reason for the existence of bicycle suspension is not comfort but safety and speed.
When the rear tire of a full-suspension bike meets an obstacle, the shock compresses. Consequently, the tire remains planted on the ground and thus the traction of the bicycle is maximally preserved.
If there’s no suspension, the tire bounces off of the irregularity and thus all traction is lost. This is one of the reasons why rigid bikes are so slow on modern trails – it’s too dangerous to ride them fast due to the lack of traction.
A suspension seat post does not provide that benefit because it has no effect on the tire. Comfort rather than traction is the goal of this product.
- “Floating Seat”
Each compression of the seat post changes the effective height of the seat. As a result, the saddle is constantly floating. Some people don’t like that feeling.
This doesn’t happen with full-suspension bikes because the compression of the shock does not change the distances between the pedals and the seat.
- Non-compatible With Most Saddlebags
Suspension seat posts are not compatible with the vast majority of saddlebags out there.
The Advantages of Full-suspension Bikes
- Serious Cushioning
Full-suspension bikes offer the smoothest possible ride on uneven terrain and no suspension seat post can match that effect.
If this is your goal, a full-suspension bike is the way to go.
- Rear Wheel Traction
As already explained, the suspension on a bicycle increases traction by allowing the tire to stay on the ground upon meeting an obstacle. Consequently, full-suspension bikes cover serious off-road terrain.
- Consistent Seat Height
The shock of a full-suspension bike does not change the height of the saddle. Thus, the rider doesn’t have to deal with a floating seat.
- Compatible with Saddlebags
Full-suspension bikes are compatible with most saddlebags because the seat post is rigid and the distance between the seat and the pedals does not change.
The Disadvantages of Full-suspension Bikes
Full-suspension bikes cost as much as low-end dirt bikes. Consequently, they’re used primarily by dedicated mountain bikers and rarely if ever serve as commuters because locking them outside is just too risky.
If you don’t think that you will get maximum advantage from a full-suspension bike, it will be wiser to avoid the purchase.
- Inefficiency on Paved Roads
The qualities that make full-suspension bikes good off-road machines make them a poor choice for paved roads.
The problems are:
a. Poor energy distribution – the suspension eats some of the pedaling effort. Hence why you will never see suspension on a road bike. (Note: This downside can be negated by locking the suspension if that option is available.)
b. Weight – suspension bikes come with a noticeable weight penalty
c. Drag – modern MTBs have an upright geometry that gives the rider control on technical terrain but hurts the aerodynamic properties of the bike.
Note: Those downsides can be compensated by relying on an electric model.
- Limited Bike Choices
If you want a full-suspension bike, you’re pretty much stuck with a single bike type that may not suit your style of riding.
- Non-compatible With Many Commuting Accessories
As already mentioned, most rear racks and fenders aren’t designed for full suspension bikes.
The Prime Candidate For a Suspension Seat Post
Suspension seat posts are recommended to cyclists that have the following characteristics:
- A need to add minimal and yet noticeable shock absorption to the rear of the bike without buying a new bicycle.
- A preference for bicycles that cover gravel and light XC terrain
- Little or no love for saddlebags
- Desires to preserve the original efficiency of a commuting bicycle while also making it more comfortable.
- Constrained by a limited budget
The Prime Candidate For a Full-suspension Bike
A full-suspension bike will be beneficial to riders who have the following profile:
- A need to cover extreme off-road terrain
- Desire to compete in the sport of mountain biking
- Large budget