Understand the basics of eMTB suspension setup

AMFLOW

28/02/2025

Ebike suspension is crucial to how your bike rides and feels on the trail. Not only does it enhance enjoyment, it also keeps you safe. But suspension systems can be intimidating, certainly if you’re considering adjusting them at home yourself for the first time. That’s why we created this handy, simple and straightforward guide to the basics of ebike suspension systems. Even if you don’t plan on spannering your suspension yourself, having a solid grasp of the main concepts will really help you convey to the mechanic what it is you want them to do when working on your bike.

In This Article

How does MTB suspension work?

Suspension on an electric mountain bike is a way of making the ride experience more comfortable, and the bike more capable.

Using either a mechanical spring or pressurised air within a chamber (known as an air shock), the suspension system compresses when you hit something on the trail, and then returns to its previous uncompressed state. How much it compresses and how quickly it returns are variable, and can be tweaked to suit your preference and the riding environment. An electric bike with suspension functions the same as a conventional mountain bike, at least in so far as the principles governing the way the system works.

What is travel in mountain bike suspension?

Travel is how far your wheel can move up and down when the suspension on your bike is compressed. The more travel, the more pronounced and noticeable the vertical movement of your wheel.

The amount of travel is given in millimetres, and typically you’ll see two numbers – one for the travel of the fork (at the front) and one for the shock (the rear suspension system).

Some bikes, known as hardtails, have no rear suspension so if you only see one number in mm that’s probably why.

Different amounts of travel are used on different styles of mountain bike. Downhill and enduro bikes typically have the biggest travel to absorb big hits from dropping off obstacles and hitting big jumps. You can expect 160-200mm of travel on these types of bike.

XC and lightweight trail bikes typically have around 100-140mm of travel at the front with 130mm at the back. This shorter travel makes them more efficient for pedalling, a crucial factor if you’re covering long distances, or mixing climbing and descending into your rides.

Our flagship, all-mountain E-MTB platform, the PL Carbon Pro & PL Carbon, combine 160mm of front travel with 150mm at the rear. This gives you plenty of squish to play with when moving over rough trails with plenty of obstacles. It’s all about versatility and the freedom to ride adventurously.

MTB sag: suspension’s sweet spot

Sag is one the adjustable characteristics of your mountain bike suspension system. It’s perhaps the easiest one to understand.

Sag refers to the softness of your suspension and the amount of your bike’s available travel that is used to support your weight. It should be tuned to each individual rider’s weight, so two e-MTBErs – one weighing 50kg and one weighing 80kg – who each ride a PL Carbon Pro would have their MTB sag set entirely differently.

You might be wondering how to set sag on a mountain bike. Luckily, it’s quite simple to do. Sag is adjusted by adding or removing air from an air shock using a shock pump, or on a mechanical coil system by adjusting the preload and spring rate.

The consequence of having your sag set up wrong basically comes down to efficiency and comfort. If sag is set too high, you’ll feel like you’re bouncing around all over the place on top of the bike, or if it’s too low, you’ll feel every single bump in the trail and struggle for traction. Ideal sag is around 20-35% of your total available travel, but this is a benchmark from which you can fine-tune your own bike to your preference.

Rebound & rebound damping: how you bounce back

Rebound is, to put it simply, how quickly your suspension bounces back to its ‘default’ fully extended state after compressing. Rebound damping is the resistance that the suspension system applies to that rebound… the more damping, the more slowly the suspension will ‘snap back’.

Having rebound that is too fast (caused by damping that’s too low) will lead to a very jagged feeling ride, where you’re being bounced or jarred whenever the bike goes over obstacles.

You can set the speed of your suspension’s rebound using dials on the underside of the fork or rear shock. Typically they’ll have a + and - symbol, or the words ‘fast’ and ‘slow’ which makes it quite easy to understand.

Compression & compression damping: impact control

Compression is the rate that the suspension compresses during an impact. You can think of it as the opposite to rebound. Compression damping – just like rebound above – is how much resistance the system exerts to slow the rate of compression.

If you don’t have enough compression damping, your bike will feel really slushy, like it’s bouncing around a lot. Your travel will activate while you’’re just pedalling along normally, making the experience very inefficient. Compression can also be adjusted like rebound – and the dial to control it is usually blue.

Setting MTB suspension on your Amflow e-bike: FOX suspension setup

Both models in our Amflow PL Carbon e-MTB platform employ a FOX fork and rear shock – and as a starting point we’d always advise checking what the fork manual indicates as the optimal amount of sag. FOX tends to advise between 15-20% of the available travel, so for the 160mm travel available on the PL Carbon Pro, you should be aiming for between 24mm and 32mm, depending whether you want a firm or a plush setup.

Amflow PL

The Amflow PL electric mountain bike offers 850 watts of power in an ultra-light sub-20kg build. With an unrivaled combination of power, range, and weight, it delivers the ultimate ride.

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