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July 02, 2022
In this Ebike Suspension FAQ, we answer some of the most common questions about bicycle suspension components found on ebikes.
There are several types of bike suspension. These include front shocks, also know as a suspension fork; rear shocks, also know as rear absorbers; suspension seat posts; and spring-loaded bike saddles.
In each of these systems, there is a mechanical shock absorber which reduces the impact felt by the rider. These systems work by using spring coils, pressurized air, or hydraulic fluids to dampen or absorb the linear movement. The suspension system lets the wheels move up and down to small absorb bumps, while keeping the tires in contact with the ground for better control. They can also absorb larger bumps when the rider lands a jump.
For front and rear shocks on a bike, there are two essential components: the spring and the damper. The spring allows the suspension to move up when the wheel encounters a bump in the road, and return quickly to its neutral position once the wheel passes the bump. The further the spring is compressed, the more force it will take to compress it. The damper is a mechanism that dissipates the energy and keeps the suspension from bouncing out of control. Otherwise, without the damper, the spring would bounce up and down several times after each bump.
A suspension seat post can prolong the comfort of the rider, by smoothing out the rough and rugged terrain. It features a dual link suspension system, which reduces the vertical movement of the seat post. These devices can help reduce lower back strain that occur when riding for long periods of time on bumpy terrain.
Suspension is not required on an electric bike. If you will be riding in areas with well-paved surfaces, and your bike is equipped with a comfortable gel saddle, the added cushion from suspension is not needed. In addition, if you have a fat tire electric bike, the tires can be deflated down to 5psi, which will allow them to absorb some of the bumps in the road. Many mountain bike riders will also prefer not having rear suspension (a hardtail configuration) as it will give them more direct feedback on the surface conditions and greater transmission of their pedal power into forward bicycle movement.
The majority of electric bikes come outfitted with suspension forks, so it’s not a decision you will have to make. In general, having front shocks is worth it. They will absorb minor bumps in the road, bringing relief to your hands, wrists, elbows, shoulders and neck. Suspension forks add comfort to your ride, allowing you to ride for longer distances with less strain.
It really depends on the type of riding you will be doing. If you want a simple cruiser for easy rides downtown and along paved trails, then suspension is not really needed. There would be no harm in having a bicycle with suspension, but there wouldn’t be a lot of bumps for the suspension mechanism to absorb. Likewise, if you have fat tires, they will absorb some of the shock that could come from riding over a curb cut or pothole. For more information on fat tire ebikes, check out our Fat Tire Electric Bike Showdown!
By contrast, if you plan on riding where the surface is uneven, and want the benefit of shock absorption, then a bike with front shocks would be a nice choice.
The suspension fork on a mountain bike has an important role to play in the handling and comfort of your bike. For many years, the standard front shock on a mountain bike, including electric mountain bikes, has been air forks. In recent years, performance improvements in coil fork design has resulted in something of a comeback for coils, particularly for enduro and trail riding.
Air forks have a progressive spring rate, meaning the fork becomes harder to compress as it travels through its compression range. A good air fork design will allow the air pressure inside the chamber to be adjusted, so that you can make the fork stiffer or softer, by increasing or decreasing the pressure, respectively. Most air forks have a lockout mechanism to prevent the fork from compressing.
In contrast, coil forks use a metal coil spring made from steel or titanium to provide resistance (shock absorption). The linear spring rate of coil forks means that the force required to compress the spring increases throughout the travel range of the fork.
Air forks tend to be a little lighter than coil forks, weighing around 3-4 pounds, compared to 4 pounds or more for a coil fork. On a high performance mountain bike, this weight difference could be significant, but for most ebike riders, they will not notice the difference.
The decision to get a bike with suspension is a personal choice, based on the terrain where you will be riding most of the time, and the type of riding you will be doing. For casual cruising, a bike with suspension is not required. However, if you plan on riding off-road, you may enjoy the added comfort that comes from a bike with suspension.
Suspension forks are often included on ebikes, so you do not have to worry about the added cost of this component. You could replace a hard fork with a suspension fork, but we recommend having a professional bike tech do this.
Front suspension on an electric is not necessary, but as noted elsewhere in this article, it can provide an extra level of comfort when riding. If you will be cruising on smooth, paved streets, then a suspension fork is certainly not needed. Even when encountering small bumps along the way, you certainly can enjoy the ride without having suspension components on your bike. But if you like an added level of comfort, it’s nice to have front suspension on an ebike.
A lockout is a switch located at the top of the right stanchion which can decrease the low speed compression rate of the front fork, adjustable to the point of being full rigid. On some advanced models, the lockout switch can be routed to the handlebar for easier activation.
What is the benefit of a lockout? Why would you want to turn off the suspension on your mountain bike fork? Well, you do not always need the cushioning effects of a suspension fork, for example when you transition from rough trails to smoother surfaces. The disadvantage to having a full suspension (or front suspension) is that when riding your mountain bike on pavement or uphill, there is a great deal of energy that is being absorbed by the suspension. This is lost or wasted energy that does not help to propel the bike. This can make it much more difficult to scale steep inclines or get up to speed easily.
All mountain bike suspension, whether fork or rear shock have 2 main functions which are performed by the spring and the damper. The spring primarily provides resistance while the damper provides the control of that resistance. There are two types of springs: air and coil.
Bikes with a rigid connection to the rear wheel are call ‘hardtails’. If the bike has both front and rear suspension, it’s referred to as ‘full-suspension’. Additional suspension components can be found at the seat post and saddle.
Rear suspension can have a number of different purposes, from improving comfort to increasing traction in rough terrain. Independent of its purpose, rear suspension always works by the same principle; a spring suspends the rider while a damper absorbs energy coming from impacts on the rear wheel. Designers and engineers have created different suspension designs over the past decades, all with different riding characteristics. The characteristics of pedaling, braking and impact absorption define suspension design.
Many rear shocks (as well as front forks) have a lockout feature, which essentially stops it from compressing, and “locks out” the shock in a fixed position. This is used to at specific times when riding to help prevent wasted pedaling energy in the form of bobbing of the suspension. Simply turn the switch to engage the lock out function.
When considering the pros and cons, we do it in comparison to bike with a rigid fork and a hardtail.
Advantages of suspension:
Disadvantages of suspension:
For your suspension to perform at its best, it must be able to respond to every contour of the trail. When you hit an object, your fork and shock compress, absorbing the energy from the impact. This, in turn, is released by extending back out again. To maintain traction, suspension forks and shocks not only have to absorb impacts but also extend to fill holes and keep your tires on the ground. In order to let the suspension both compress and extend, we preload the suspension with our own body weight. The amount of preload is known as sag, literally the amount the suspension sags into its travel when you sit on the bike. Too little sag and the bike will lack grip as it cannot extend into compressions, too much and it will wallow and respond poorly to repeated impacts. Detailed instructions can be found here.
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