We've heard practically every excuse in the book from sportbike riders who refuse to mess with their suspension, from, "I don't know what knobs do what," to, "It works OK how it is." We've even heard reports of people riding into their neighborhood dealer, copy of Sport Rider in hand, asking to have their bike set up just like we say. We're flattered, but that's not the point of the suggested settings we print with each test. As for other excuses, most of them boil down to the same reason your VCR is probably flashing "12:00." And you know why that is, don't you?

What's all this ruckus about suspension these days? It seems everyone is clued in that suspension setup can be a key to riding fast and safely, but how do you do it? No matter what shock or fork you have, they all require proper adjustment to work to their maximum potential. Suspension tuning isn't rocket science, and if you follow step-by-step procedures you can make remarkable improvements in your bike's handling characteristics.

Thrust And Horsepower
When you look at a dyno chart, you see that a bike might have a horsepower rating of 65 at 4000 rpm. Say your primary drive ratio is 2.000, the final drive is 1.500 and the gear you are in has a ratio of 1.000. You multiply 2.000 x 1.500 x 1.000 and get 3 (which would be your overall gear ratio), then take that and multiply it by your 65 horsepower. Does that equate to 195 horsepower at the rear wheel? Is that what your bike is putting down, or is it already figured in when you look at the dyno chart? Can you compare two dyno charts and gear ratios to see which bike might be faster? If this is the case, then a higher dyno number does not always equal a quicker bike, right?
James Patterson
Erin, TN

Hoop Dreams
Why are many aftermarket wheels labeled as racetrack only? Wouldn't a carbon or magnesium rim work just as well in the canyons as it would on the track? And why do racebikes have smaller wheels than stock bikes? How do the smaller hoops affect performance?
Vince Davis
Los Angeles, CA

In Our Last Two Installments Of Art & Science we covered the basics of data acquisition (Jan. '08) and analyzing engine rpm data (Mar. '08). Speed and rpm, generally considered the two most important channels, are almost always given dedicated inputs on data acquisition systems and provide plenty of information on their own. As always, however, more data from other sources can allow you to better analyze that speed and rpm info, as well as look at other aspects of setup and riding that speed and rpm traces on their own can't reveal.

We Never Get Tired Of Tire Questions
I ran Michelin Pilot Power 120/70-17 and 190/50-17 on my '99 GSX-R750. The grip level and the mileage of this tire were pretty impressive and I was determined to use it again. However, when the tires were finished I changed to a used set of Bridgestone BT-002 Race 120/70-17 and 190/55-17, which I had been using on another bike for track days. With the Bridgestones on my GSX-R it feels like 20kg less. Steering is so much lighter and it's lot more fun to ride, although stability is compromised. Now I am lost. The BT-002 Race is not street legal, and I do not know if I can get the same feeling with the BT-002 RS in the same dimension. Or is the different feeling mainly due to the change in dimension from 50 to 55? In such case I could use the Pilot Power 190/55-17 or the 190/50-17 and adjust the ride height (I have an adjustable hlins rear shock).
Robert Schuhmayer
Austria

In last issue's Art & Science we discussed the basics of data acquisition and different ways to interpret speed data. Speed-whether recorded by a GPS-based system or a unit that measures wheel speed-is generally the base channel and offers plenty of information on its own. Adding more channels, however, allows a more in-depth analysis of the motorcycle's and rider's behavior on the track. That higher level of analysis can in turn result in quicker development and improved overall performance from both the bike and rider.

Y= MX + B
I'm an avid track-day rider and I have a chassis geometry question. My pace at the track has really improved over the last year, and I'm trying to understand more about my suspension and chassis. To make a bike turn in better and feel lighter, you can either lower the front or raise the rear. I don't believe it matters which way you go, as the end result is the same chassis geometry (except that if you lower the front, the bike's chassis is lower, and if you raise the rear, the bike's chassis is higher).

In the first three installments of this series we looked at data gathered by various sensors attached to the acquisition system: speed, rpm and throttle position. In this segment we'll deal with channels derived from position data collected by GPS-based systems that don't require any additional sensors. GPS setups, which calculate ground speed based on the change in position over time, can use that data to calculate acceleration forces in any direction, a helpful addition when it comes to evaluating performance.

Dave's Saggy Shock
I've got an '03 GSX-R1000 with a bit over 14K miles on it. The shock has started feeling a little mushy, and I'd like to get it back to how it felt originally. I remember reading that a shock would typically need to be rebuilt at around 15K miles. I've also heard that simply changing the fluid in the shock should restore its prior performance. Unless this is something that can be done by your average shade-tree mechanic, I'm probably going to just remove the shock myself and have someone else do the work on it.

Richard Was Busy This Month
Of the three motorcycle magazines I currently subscribe to, Sport Rider invariably delivers the best comparison information and test data of the three, period. I especially like the performance data you provide with your model comparisons. Rather than a lot of seat-of-the-pants subjective opinions, your staff provides graphs and charts to show why one bike is faster or laps quicker than another. As an engineer, this is the stuff that makes your comparisons meaningful and provides objective credibility to your bike recommendations.

While the general public was eagerly awaiting Internet spy photos of the new '08 Hayabusa, the team at Velocity Racing had already taken delivery of an actual example of the breed and was busy building the bike it would soon be using to campaign in the AMA Prostar Pro Street class. Anyone who follows motorcycle dragracing knows of Velocity's reputation for constructing race-winning machinery since bursting onto the scene in '01. Under the leadership of Barry Henson (owner and rider), Velocity has had an impressive string of nine national championships, and it's not out of the question to believe it will be adding more in '08.

With the new era of 800cc MotoGP well underway, our spies in the paddock have managed to snap some pictures of the new bikes. Here is a sampling from the first few races of '07.

PRODUCT ROLE AND POSITIONING

A MotoGP-inspired Hypersport Tire for Street Superbikes. The BT-002 Racing Street provides legendary front end contact feel and cornering performance proven by Bridgestone in MotoGP. A hypersport tire designed to provide best performance on the road for pure sport riding.

Twenty-two thousand miles. That's the sad tale told by the odometer of Brad Roller's 1996 Yamaha YZF600. Trevitt likes to cast a supercilious glance down the flanks of such two-wheeled stalwarts and proclaim each a "creaky old pile." That's to say his tastes run toward the still-smells-of-new, preferably owned by someone else. (Don't ask about his dusty GSX-R600.)

The first day Pirelli's 2006 tire test at Daytona International Speedway saw great results by every team involved. Following a year of earning 16 podium finishes in the AMA Superbike Series, Pirelli showed its continued upward move in its commitment to road racing in the USA, during its annual tire test. This year's Pirelli's tire test included the Fast by Ferracci Superbike team, Team M4 EMGO Suzuki, Team Roadracingworld.com, Attack Kawasaki, Moto Uno Racing, Team Hotbodies Racing, Longevity Racing, and other pro riders.

Avon is to launch a new sport-touring tire range named Storm-ST, replacing its highly popular Azaro-ST product. Storm-ST has already been tested and approved for fitment to all major motorcycles in conjunction with the well-respected German TUV agency.

Michelin has welcomed new regulations designed to maintain competitionbetween tire manufacturers in the MotoGP World Championship. The twosets ofrules, concerning tires and testing, come into effect on January 1,2007.The tire regulations, the first such restrictions to be introduced toGrandPrix motorcycle racing, were formulated following discussions betweenthethree tire manufacturers involved in MotoGP.

MotoGP is all about racing and winning but success during the summer racing season can usually be attributed to behind-the-scenes work during winter testing. Indeed riders cover many more laps during winter tests than they do actually racing. Nicolas Goubert, Michelin's director of motorcycle racing, explains how the French company goes about its winter testing program in order to be best prepared for the next MotoGP World Championship. The some of Michelin's best MotoGP riders take their turnS

We've known for some time now that repeatable, consistent dyno readings depend on a number of factors, and one anomaly that crops up now and again is tire selection and wear. The scenario can play out in a number of ways, but here are the two we most commonly encounter: One is the sportbike rider who goes to his local shop for a tuneup and new tires, and his bike leaves the shop with less horsepower than it went in with. Another is the racer competing in a horsepower-limited class. He dynos his bike several times over the course of a weekend and is well under the maximum amount allowed, but after the race and a celebratory burnout, his bike is suddenly over the limit.

Due to the relentless development of bikes in the most competitive of classes: Supersport, Metzeler are constantly proving to match the bike manufacturers pace of improvement. Innovation and leading technology have always characterized the German brand.The DNA of Metzeler tire fit this trend and in recent years has driven sport bike development, based on an endless research of improving performance without compromising mileage and most of all versatility.