Today's sportbikes are blessed with incredible cornering prowess, and much of that comes from their excellent ground clearance. Keeping hard parts like exhausts and engine cases from dragging on the pavement during aggressive cornering allows a skilled rider to fully exploit the superb grip afforded by today's sticky sport tires and advanced suspension components.
But ground clearance comes at a cost. Many of the current hard-core sportbikes have seat heights ranging from 32 inches on up, due in part to the ergonomic requirements of raising the footpeg position to avoid pavement contact while cornering hard, yet keeping reasonable legroom for street use. Even some of the less frantic sportbikes, like Suzuki's superb SV650, have a seat height of at least 31 inches, making them a bit intimidating to those inseam-challenged folk among us (in other words, shorter than five foot six). It's difficult for some riders to feel comfortable on a bike that is so tall they can't put both feet on the ground at a stop.
This has often prevented riders from upgrading to a larger displacement machine. They're usually left with two choices: either stay with their current bike, or (egad!) resort to buying a cruiser-type machine with their substantially lower seat heights.
There is one alternative, however. It is possible to lower a sportbike slightly, so that at a stop a shorter rider can comfortably reach the ground with both feet. We're not talking about "slamming" a bike down to the ground dragbike-style; we're referring to riders who still want to experience the cornering fun that a current sportbike can provide. While there are some definite disadvantages to lowering the suspension, it does give shorter riders the opportunity to ride sportbikes that they'd ordinarily shy away from.
We must stress the fact that lowering your bike has some real disadvantages. First and foremost is ground clearance-if you corner very aggressively, you will drag parts sooner and easier than another rider on a standard-suspended machine. Some of these parts-like engine case covers or exhaust systems-can lever the rear tire off the ground if you're not careful. You MUST remember this if you plan on lowering your bike.
The ground clearance factor means there's also a limit to how much you can lower a sportbike. Nearly all of the suspension technicians we spoke with said for riders who don't intend to drag race, 1.5 inches is the limit they would be comfortable with for shortening suspension. Anymore than that severely restricts the amount of lean angle the bike can achieve without running into ground clearance problems.
The second consideration is cost: DONE PROPERLY, lowering is not cheap. Yes, the rear suspension "lowering links" that are on the market only run around $120, but having a skilled suspension shop shorten your bike's fork can run upwards of $300. Plus you'll need to shorten your bike's kickstand, which can run you another $50 to $100.
Why Can't You Just Raise The Fork Tubes In The Triple Clamp?
Those of you who use our recommended suspension settings as a starting point have noticed that we often lower the front end to compensate for different tires by raising the fork tubes in the triple clamps. So why not just lower the front end even more by using the same method? The reason is that there's very little room to play with before the front fender and tire hit the lower triple clamp under hard braking. This could cause the fender to jam itself into the tire, resulting in the front tire locking up, and well...you know what happens next. Shortening the suspension basically brings the fork or shock farther down into its travel, while altering the spring rate so that it behaves normally (more on that later).
On most bikes that run the top of the fork tubes flush with the top triple clamp, raising the tubes about 15mm is the safe limit before you'll run into clearance problems with the front fender/ lower triple clamp. If this is sufficient to get the seat height low enough so that you feel comfortable at a stop, you're in luck. Some sportbikes run the tubes slightly higher than the top triple clamp in stock form, and a few have graduated marks on the fork to ease height alignment on both tubes. The lowest mark on the tube is often the limit for raising the fork in the triple clamps. However, ALWAYS CHECK CLEARANCE BEFORE RIDING WITH THE FORK TUBE AT THE LOWEST MARK. The only real way to do this is to raise the bike's front end off the ground with a proper stand (one that raises the bike from the lower triple clamp, NOT the race stands that prop up under the bottom of the fork tubes), remove the fork springs and slowly raise the fork until it bottoms out.
Lowering links are a cheap...
Lowering links are a cheap alternative to shortening the rear shock, although using them compromises the progression rate of the rear shock linkage, making them more prone to harsh bottoming.
The link with oversize eyelets...
The link with oversize eyelets replaces the bottom yoke portion of the Yamaha R1/R6 series linkage (photo B), while the smaller piece is intended to replace the "dog bones" of the Suzuki Hayabusa linkage (photo A).
DON'T JUST LOWER ONE END-Maintain The Correct Chassis Attitude
Any time you lower either end of a motorcycle, you must lower the opposite end an identical amount. Unless you want to change the bike's steering characteristics (which should only be done if you have a comprehensive grasp of motorcycle steering geometry), you must maintain the bike's chassis attitude to avoid handling problems. Changing the front or rear ride heights by as little as 5mm can have a dramatic effect on how a bike handles in the corners.
Some sportbikes have graduated...
Some sportbikes have graduated lines on the fork tubes that allow easy adjustment for raising or lowering front end ride height. If you try to use the lowest mark, always check to make sure that you have sufficient clearance between the lower triple clamp and the front fender.
This is why it's essential to use the correct spring rate when lowering either end of the motorcycle a drastic amount. Shortening the fork requires cutting the fork springs in order to maintain the correct spring rate, otherwise the fork will ride extremely stiff since it will be at the bottom of its travel. It's also necessary to check suspension sag measurements (like you'd normally do) after modifying, using slightly smaller figures to compensate for the shortened suspension travel; that way the bike will maintain the correct chassis attitude during cornering, instead of riding higher on one end or the other.
The majority of current sportbikes use a cartridge fork, which employs an oil damping mechanism housed in an internal cylinder to handle suspension control. Shortening the fork requires disassembling the cartridge; this is a delicate piece of equipment, and taking it apart requires specialized tools and a person skilled in handling these components. Even shortening a traditional damper rod fork requires some mechanical expertise, so this is a job best left to a specialist. On the West Coast, try Lindemann Engineering (408/371-6151, www.le-suspension.com) or Race Tech (909/279-6655, www.racetech.com); or Traxxion Dynamics (770/592-3823, www.traxxion.com).
Shorten The Shock Or Use Different Rear Suspension Links?
This is an area in which cost is a consideration. There are many aftermarket rear suspension links now available that replace certain parts of the rear shock linkage with a length-adjustable component, allowing the rider to adjust the rear ride height if the shock is not adjustable for ride height. These are inexpensive, costing anywhere from $120 to $250. They are easy to install, and usually simple to adjust in order to obtain the desired ride height. The only drawback is that lengthening the link in order to drop the suspension changes the shock linkage's progression rate; modifying the length on some linkages by as little as 10mm can increase the progression rate by 20 percent. This means that you run the risk of having a pretty stiff suspension, and simply installing a softer spring will only solve part of the problem. It's best to consult a suspension expert on your bike's particular shock linkage with regards to this option.
We cannot emphasize enough...
We cannot emphasize enough how important it is to remember that you will have COMPROMISED GROUND CLEARANCE AFTER LOWERING YOUR BIKE. Hard parts that normally would stay off the ground at stock ride height will drag if you corner aggressively on a slightly lowered machine. BE CAREFUL.
The other alternative is shortening the rear shock, which is accomplished in a similar manner to the front fork. Again, this is not cheap; the conversion will probably run you about $230-$250. However, your shock linkage's progression rate will remain stock, and cutting the shock spring to the proper length will ensure that you'll have the proper spring rate. Lindemann Engineering can shorten nearly every stock and aftermarket shock on the market; call them for details. Lastly: DON'T FORGET TO SHORTEN YOUR BIKE'S KICKSTAND, otherwise, your readjusted steed will refuse to stand up on its own.
Although lowering sportbikes is more commonly associated with dragracing, the new breed of sporting machinery has sufficient ground clearance to handle some slight lowering for those individuals who feel more comfortable having both feet on the ground at a stop. As long as you remember the limitations of this modification, and get the proper professional technical assistance to set up your bike after being modified, you'll be able to experience nearly all of the exciting performance of today's sportbikes you thought you'd miss out on.