Lowering a Motorcycle, Correctly!

[SSR Suspension]

Regardless of your reason for lowering your bike, it's not a task to be taken lightly. So before you consider lowering your bike I need to draw your attention to some of the drawbacks that can adversly affect the handling of your motorcycle.

Drawbacks: DONE PROPERLY, lowering is not cheap, it requires modification to the shock and forks internally. The linkage system is an integral part of the rear suspension, each linkage system is designed to work with specific shock damping, spring rate, ground clearance, etc. When you add longer lowering links, it changes the leverage ratio, which can cause all sorts of problems. You might find that the rear shock bottoms out sooner and feels softer in the last portion of the stroke, or sometimes the effects can be unpredictable.

By lowering the shock position, you also make it more vulnerable to impacts on the trail/road. Another danger to keep in mind is that you’ve moved the rear wheel closer to the rear fender without reducing suspension travel. This can cause the rear tire to touch the fender on big hits, which can lead to a crash. We do not advocate the use of lowering links, so if you install your own links check with the lowering link manufacturer to ensure their lowering links offer enough rear fender clearance for your model.

When lowering a motorcycle you will also require the machines side stand to be shortened, this would need to be done by a competent fabricator/welder and is not something we can provide.

Alternate Options: A lower motorcycle seat can help you avoid all the unintended consequences of lowering a motorcycle’s suspension, like reduced ground clearance, less suspension travel or a harsher ride. You can lose up to 2 inches with a low seat and it’s a quick and easy install. Some “low” replacement seats can be bought right off the shelf from manufactures like Corbin, Seat Concepts and Touratech.

Lowering your motorcycle: We can lower any motorcycle correctly with the lowering height dependent upon the application of the motorcycle, we do not recommend lowering a street bike more than 25mm. Due to the change in geometry you should lower both the front and rear of the motorcycle by equal amounts, if you forgo this you will cause further handling issues due to an imbalance in the geometry of the motorcycle.

Theory: A shock's lever ratio is determined by the angle at which it's mounted. To better understand this concept, picture a bike's rear suspension, including the swingarm pivot, the rear shock's lower mount and the rear axle. Next, imagine the rear wheel moving though its travel, which describes an arc, and draw that arc. The distance the rear axle travels typically will be farther than the distance traveled by the shock's lower mount. At the extreme, the shock might be moving two inches, and the rear wheel four inches.

Different models of motorcycle have differing levarage ratios the drastic change in lever ratio that results from using lowering links essentially makes the shock stiffer, reducing ride comfort. Shocks are engineered for a particular model so as many forum experts claim, using a shock from another bike is NOT the solution. For example, a Harley-Davidson Dyna Glide shock will not work on a Sportster because the lever ratio is different. The shocks on a Dyna are moved way up, and they have heavy damping and 300 pound springs. The spring on the Sportster shock is a 100-pound spring and the damping is lighter, switch them and they'll be either too soft or too hard on the wrong bike. The spring has to be right, and the damping has to match the spring.

Even if you lower your bike by the book, handling can be affected to some degree. When you lower a bike, you also lower its center of gravity, so it'll handle a bit better in certain circumstances however the negative is that your initial ground clearance is decreased. That’s not the only thing you’ll notice during your first ride on your just-lowered bike. You’ve given up travel, so your comfort will suffer. The more you lower it, the more ride quality and comfort suffer. Two inches of travel won’t do the same job as four inches of travel. Why? The springs must be stiff enough to keep you from bottoming out and that is why springing a bike for your weight is so important, also the shocks usually need heavier damping to match the heavier springs, which leads to compromises that might force you to re-consider lowering in the first place.

You should also be prepared to give up some load capacity: You can't make a bike low and have the same load capacity. That's because you lower the bike at the expense of suspension travel, the reduced travel means the bike can bottom out easier. Those planning on extended two-up riding should forego lowering. If you want to pack some gear and a passenger and ride across the country on a lowered bike, you're not going to be happy.

If you still feel that you wish to have your bikes suspension lowered email us to discuss your requirements.

[Yorick]

Blimey, I was just thinking about this. My Husky TE300i is a bit high for my little legs. Can't get on it sometimes after a tumble. My pal bought his KTM300i from a dealer who'd wound the preload right in on the shock and it's lowered the seat by about 2 inches. I can get my heels down, rather than only toes.

Is it a good idea?

[SSR Suspension]

God no, adjusting the preload will affect the dynamic geometry of the bike because it controls how much or how little the bike sags, however the rider sag on an Enduro bike should be circa 105-110mm at the rear. Too much preload will also make the bike feel harsh, it will sit too low in the stroke and run wide on a corner and sitting low will mean you have less suspension travel for absorbing the bumps. Off road bikes run quite small amounts of preload when you have the correct spring for your weight.

Off Road bikes still require the same element to lower them but because you have circa 180-200mm of suspension travel the lowering effect has far less drastic conseqeunces. I have lowered a KTM 350 75mm previously, because the customer wanted to use it for green laning only. On an off road bike 25-50mm is average, 75mm is the extreme but achievable.

I have a KTM 250 coming in next month that I lowered 25mm but the rider is 5ft and still can not cope so I am taking it to 75mm for her.

Again, spring rate has to be taken into account as well as damping because damping is relative to spring rate, so to do it properly the job is not cheap.

Bear in mind an average road bike only has 120mm of wheel travel aka suspension travel at the front and the rear vs an Off Road bike with circa 200mm.

I will do a post on preload and sags later in the week. You also have the WP Xplor fork on that bike which does not work, the damping adjusters have nil effect on the damping regardless of where you set them!