A lot of stock mini bikes have rigid all steel frames that are durable and capable of handling the abuse of tough trails and heavy loads. However, without any suspension, they also make for a very bumpy ride, but this doesn’t have to be the case. There are some easy options that will make for a much smoother ride.
A few ways to improve a mini bike’s suspension is to lower the air pressure in the tires, add front forks, add a springer seat, and add custom rear suspension shocks. Depending on how much suspension you need, you could do one or all of these modifications. Let’s take a look at the pros and cons of each of these options.
Lower tire pressure
Letting some air out of the tires is by far the easiest, fastest and a free way to enhance your mini bike’s ride. Less air in the tires gives you a smoother ride because the tires are able to bend around objects to absorb the impact.
Lower air pressure also means better traction. The more air you let out of the tire, the more surface area of the tire is in contact with the road giving it a better grip. This might be especially helpful if you are riding on snow or ice.
So the question is, how much air pressure should you have in the tires? The first thing you want to do is check the manufacturer’s recommended tire pressure. The recommended maximum air pressure should be listed in the owner’s manual and written on the side of the tire.
Most mini bike tires maximum recommended air pressure is around 10 psi. Use this as a starting point and experiment with different tire pressures. Let out a little air and take it for a ride to see how it does. For most tires you do not want to go any lower than about 5 psi.
There are a few downsides to running lower air pressure in your tires. For starters, it will probably make your mini bike a little slower. The engine will have to work harder because of the extra traction. This means it will likely burn through fuel a little faster too.
Finally, you want to be careful that you do not let too much air out of the tire because the mini bike can become unsafe to ride. Lowering the air pressure increases the chances that the tire bead will separate from the rim while riding. This can be a dangerous situation especially if you are driving at a high speed when it happens.
Adding front forks
The best suspension upgrade for most people is probably adding front forks with suspension. It will make a big difference in the comfort of the ride by absorbing bumps on the trail so your wrists and back don’t have to. They are very easy to install and fairly inexpensive.
Bolt on front fork kits can be found for most mini bikes for $200 or less. You just want to make sure that the kit you buy is made specifically for your model of mini bike. The specifications for the fork kit should list which models it fits.
Front fork kits are so easy to install that anyone can do it. First, you remove the front wheel, the handlebar grips and break lever. Make sure your brake cable and throttle cable are not zip tied to the handlebars or front forks. Then remove the center steering bolt.
Once this is done, all you have to do is bolt the new forks in place, add the handlebar grips, brake lever and front wheel back on. You may also have to transfer the front fender over if you have one on your mini bike.
Adding a springer seat
A springer seat is exactly what it sounds like, a hinged seat with springs attached to the bottom of it. The hinge allows the seat to move up and down and the springs act as shock absorbers for the rider.
Adding a springer seat will take a little mechanical know-how, but there are a lot of YouTube videos out there to use as a guide. Also, you can purchase aftermarket springer seat kits designed for motorcycles that include the hinge and springs. If you have the skills and tools, you can create your own from scratch.
Whatever you decide to do, you want to make sure that your seat is attached securely and you use springs with the proper stiffness. Springs that are too soft are going to leave you bottoming out on the frame, but springs that are too stiff won’t absorb the bumps. Buying springs specifically designed for springer seats is probably the easiest way to go.
One thing to consider when making this modification is that the seat height will probably change. The seat will need to sit higher to make room for the springs underneath. This could make for an uncomfortable riding position.
Adding rear shocks
The last suspension upgrade we are going to talk about is adding rear shocks. This is no small task and will require a lot of creative engineering and fabrication. Adding rear suspension to a rigid frame mini bike involves cutting the frame in multiple places, building a swing arm with a pivot point and mounting the shocks.
You will need to cut the frame and this could significantly weaken it, depending on the frame design. So you might find it is necessary to add an additional upright just before the pivot point to provide extra support to carry the weight of the rider.
A pivot point needs to be added so that the wheel has the ability to move up and down as you go over bumps and the shocks can compress and expand again. If the pivot point is not lined up correctly with the chain sprocket or driven pulley (for torque converters) the chain will tighten and loosen as the wheel moves up and down. This can result in throwing the chain or breaking it.
If it is not possible to line the pivot point up with the chain sprocket, a couple of work arounds would be to add a chain tensioner or a jackshaft. A jackshaft is an additional axel like shaft with sprockets that transfers the power from the chain sprocket to the wheel. Adding a jackshaft changes the pivot point.
The swing arm and specifically the mounting brackets that attach the rear shocks will be under a lot of stress. So, make sure you have good welds and strong mounting brackets. You also want to determine the best location for the mounting brackets to allow the rear shocks to sit at an optimal angle to function properly.
If this sounds too complicated, there are some aftermarket swingarm kits that give you a head start on the project.
Other posts you might find helpful
Coleman Mini Bike Front Suspension Upgrade; How to Make a Mini Bike Quiet; How to make the Coleman CT200U and CT200U-EX Faster; Must Have Tools for Small Engine Repair