More Nakedness
When you did the R1 naked bike, where did you relocate the coolant reservoir to? I want to do my ZX-10R naked but it looks ugly without fairings.
Ray D
Via the internetinline_mediumwraptextright24855683/tech/146_0909_sportbike_nakedness_chains_bearings146_0909_01_z+ask_the_geek+R1_naked_bike.jpgTrue

Give Me A Brake
I have a 2004 GSX-R600 with 7850 miles on the odometer-I live in Alaska, the bike and I hibernate for half the year. I started to have a handling problem about a year ago. When the bike is coming to a quick stop under fairly hard braking at speeds under 30mph, the handlebars will start to bounce up and down like you're using a jackhammer to break concrete. You hear a really nasty sound kind of like Godzilla's roar and your fillings literally fall out of your teeth. Now at that point you decide to let go of the brake lever and the vibrations instantly stop. A gentle application of the brake lever causes no vibration or noise all the way to a complete stop. And above 30mph even squeezing the brakes hard enough to lift the rear wheel causes no problems.

20 Questions In One
My friends and I were curious about why race teams use magnesium wheels and not carbon fiber. Carbon fiber is lighter and stronger, right? When molded into that certain application, is magnesium superior? Does it have anything to do with the limited availability of rim designs in carbon fiber or is it more cost related because of the R&D time it would take to test and produce?

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.

Dry Weight Confusion
Am I missing something here or does the dry weight that is listed by the motorcycle companies include oil and radiator weight? Or is it the gas that makes it "wet"?
B. David Bland
Germantown, MD

Wobbling Kawasaki
I have a Kawasaki ZX-14. In an effort to quicken/tighten the cornering abilities, I changed my rear tire to a 190/55-17 from a stock 190/50-17. Since the tire change I experience noticeable headshake from 45 to 55 mph. The dealership said the front tire balanced perfectly, and they are reluctant to do anything. The tires are smooth at all other speeds, and the bike handles well. Any comments concerning the tire swap and cause of the headshake would be appreciated.
Jim Cowan
Orting, WA

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.

Recommended Suspension Settings

These tables show suggested suspension settings for each bike. You can also use the tables to find which issues of Sport Rider each bike was tested. For more information on suspension, check out the Suspension Tuning Guide.

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.

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:

If you attended the MotoGP event this year at Mazda Raceway Laguna Seca (or, if you are lucky, a round overseas), you no doubt heard many of the bikes coughing and sputtering as they miss on acceleration. This is not because of some mechanical problem, but rather the engine is cutting out momentarily as the bike's electronics limit power to the rear wheel for traction control.

CLERMONT-FERRAND, France - Michelin's motorcycle racing director Nicolas Goubert reveals the secrets behind Michelin's MotoGP qualifying tires:

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.

As sportbikes become more and more powerful, rear-end geometry plays a greater part in determining how well that power gets to the ground. Some production bikes now have adjustable swingarm pivots, which is one part of the equation, and while the pivot height--which can be used to change the swingarm angle--plays an important role in antisquat geometry, there is much more to consider.

Resources and links for each wheel:

Recently, while running a 2003 Yamaha R6 through the gears, I noted that the bike seemed to lunge forward when shifting from fourth to fifth gear and again from fifth to sixth. It was almost as though the engine was relieved to be in the taller gear and was therefore rewarding me with more forward thrust. I was shifting the bike at redline, so how could this be? Redline is the correct shift point, right? So I pulled some dyno charts on the R6 and noted that peak horsepower is at 12,750 rpm, yet the factory tach shows redline at 15,500 rpm. With this much overrev, it made me think about what the ideal shift points should be.