This post will explain the benefits and the downsides of having suspension (i.e. shock absorbers) on a bicycle. For ride comfort, it is also worth reading the post about bicycle frame’s affect on comfort.
1. What is suspension on a bicycle?
2. Characteristics of (good) shock absorbers (suspension)
3. Types of suspension
4. Pros and cons of suspension on a bicycle
5. Conclusion – suspension: yes, or no?
Tyres filled with air (pneumatic tyres), an invention of John Boyd Dunlop, is a basic type of suspension used on practically all the vehicles with wheels. Pneumatic tyres provide improved wheel traction as well as dampening of most road vibrations and shocks from road irregularities (i.e. potholes and bumps).
Still, the higher a speed and the rougher a road (or off road), the greater the impacts, so tyres on their own are sometimes not enough to absorb the shocks in order to keep the ride comfortable and prevent the vehicle form jumping up and down, loosing traction and control. That is where, what is meant under a term “suspension” comes in play: shock absorber(s). Their job is to (additionally) dampen all the road shocks/irregularities. In cycling jargon, bicycles with front wheel suspension are called “hardtails“, while bicycles with both wheels suspension are called “full-sus“, or “full suspension” bikes.
Function of a shock abosrber is to allow the wheel(s) to follow the curves of the road, without much movement of the rest of the vehicle. Small vibrations (buzz) is still mostly dealt with by pneumatic tyres, they are still necessary for a safe and comfortable ride. Shock absorber (suspension) allows “flattening out” larger terrain irregularities. How do they do that? By compressing and expanding. While doing that, they allow the wheels to move up and down, relative to the rest of the vehicle (bicycle frame), so the effect of potholes and bumps is highly reduced. They also have a dampening effect (more or less), so that after compression, they relatively gradually expand back to the preset position – not jumping back like a pogo. Picture 2 shows the movement range of a bicycle suspension fork. Legs can move both down (to a lesser extent) and up, from a preset position.
Features a high quality bicycle suspension should have are the following:
- Preload adjustment – how much the suspension compresses under static rider weight – i.e. when you sit on a bike.
- Compression adjustment – how much does suspension resist compression.
- Rebound damping adjustment – how strongly and quickly suspension extends back after being compressed.
- Low weight (i.e. mass, to be more precise).
- Good quality – durable, strong, availability of spare parts.
- Lockout option – so it can be turned off when it hampers performance (on climbs for example) – preferably via a remote control lever on the handlebars.
By this there won’t be explanations of different designs, just the parts of a bicycle for which suspension is made. So, in short, there are suspensions for:
- The front wheel – suspension forks
- The rear wheel – rear triangle of the bike is connected to the rest of the frame via a rotating joint with a shock absorber
- Saddle – seat post with an in built shock absorber
- Bars – stem with an in built shock absorber
There are some other types of suspension, but they are not common (very exotic) and of questionable comfort benefit. Of the four noted, the wheel suspensions are the most important for improvement of bicycle’s comfort and handling.
Suspension seat posts are a bit of a special case. There are (expensive) models that don’t cause (much) change of the distance from the saddle to the pedals when the suspension travels (picture 3a). Using a system of parallelograms. Cheap(er) ones go just up and down, changing the distance between the pedals and the saddle (picture 3b). This is not very good, for several reasons that are beyong the scope of this post. There is a third kind of “special” seat posts, called dropper seat posts. These seat posts allow the saddle to drop by a relatively great amount, for about 15 cm, by just flipping one switch, for easier acrobatic riding 🙂 and it also allows quick return of the saddle to the original position, for easier pedaling (picture 3c). So it’s not a suspension seat post in a classical way. Fourth type is a saddle with springs (picture 3d). Good quality ones have strong springs that compress only on large(r) bumps, making the ride comfortable, without making pedaling problematic by always bouncing up and down. The downside is they are rather heavy.
When explaining pros and cons, it will be done in relation to a bicycle without suspension, i.e. “ordinary” rigid forks, seat posts and stems.
Advantages of suspension:
- More comfortable ride.
- Better control of the bicycle – better traction when cornering, even braking. This allows for faster riding on rough roads that are downhill, or flat. Of course, stem and seat post suspension mostly affects comfort (only).
Disadvantages of suspension:
- Heavier – of course, super-expensive, super-light suspension fork for example, might be lighter than a cheap, steel rigid one, but it will be significantly heavier than any decent quality rigid fork.
- Higher price – for similar quality level, parts with suspension cost several times more.
- Requires regular maintenance – service includes oil change, replacement of rubber seals, dust wipers etc. This costs time and money.
- Slows the bike down on climbs – high quality suspension usually has a lock-out option, when it doesn’t slow the bike down too much, but even when locked, it’s not completely rigid, and it’s still heavier – which doesn’t help with riding up hills.
The number of noted pros and cons can be misleading. Even though there are more noted cons than pros, the important thing when choosing is one’s riding style, conditions, budget etc. For example, somene who likes to ride fast down hill on forrest roads is a lot more likely to benefit from suspension than someone who rides mostly on pavement.
Contents of this chapter are mostly a reflection of the author’s opinion, based on personal knowledge and experience. Is suspension a good idea, or not? It depends. For one thing, there are ways to make a bicycle decently comfortable (depending on one’s criteria) without suspension. Wheelbase is one thing that can significantly affect a bicycle’s comfort. The longer it is, especially the chainstay length, the more a bike is comfortable. Also, wider tyres do wonders when comfort and off road traction are concerned. This is usually enough to make a bicycle comfortable for riding on paved roads and well tred mountain paths (although, there are people who, even for city riding, find a bicycle “uncomfortable without suspension” – it is subjective).
If suspension is the choice, it is important to remember regular service and to buy good quality (and more expensive) one. Low end suspension, without lockout and rebound damping is a rather poor choice.
For comfort, an interesting post is also frame’s affect on ride comfort.
Related post – Pros and cons of bicycle disc brakes (compared to rim brakes):
Author’s choice of “comfort oriented” bicycle parts, list for on-line shopping links at Amazon.com (as an Amazon Associate I earn from qualifying purchases):
Brooks Flyer – leather saddle with good, strong springs. Durable and comfortable for city and treking bikes.
Continental Grand Prix 4-season – 25 mm wide – comfortable road bicycle tyres with good wet road traction.
Schwalbe Marathon Racer – comes in most sizes, from 20 to 28″ wheels. Comfortable, fast tyre for paved roads.
Continental Race King – comfortable and fast rolling off-road tyre, made for 26, 27.5 and 29″ wheels.