After making the decision to head to the track this season, my attention quickly turned to determining what bike I should take with me. While momentary consideration was given to acquiring a bike specifically for track days and club racing, there was never really any doubt that it would be anything other than my trusted 2006 Honda CBR600RR taking this new adventure with me.
Friday, 10 June 2016 17:04 Published in From Street to Track with Patrick Lambie
We see all the time now road racers "backing it in" to corners, sometimes with the rear end of the motorcycle out of line with the front just as much as dirt track or supermoto racers. Using engine braking or the rear brake, these riders are skidding the tire just enough that the rear end kicks out a certain amount under braking. Done properly with careful manipulation of the controls, this manoeuvre starts the motorcycle turning before the corner, effectively reducing the arc of the turn that must be completed.
How sideways the bike goes on the entry is determined partly by how much load is on the rear tire, and partly by the amount of slip (how much slower the rear tire is turning that the bike's actual speed). The wheel's load depends on how hard the rider is using the front brake to unload the rear end, and while some of the rear braking force can be provided by the rear brake itself, most modern four-stroke race bikes have more than enough engine braking for the desired amount of slip. While a very good rider can modulate the front and rear brakes and the clutch all at the same time for a beautifully controlled slide all the way to the apex of the corner, the goal is to have close to the right amount of skidding provided automatically so that the rider need only fine-tune the action.
One method to accomplish this is to use a slipper clutch, which reduces the effect of the engine braking to manageable levels so the rider does not have to be so precise with letting the clutch out. On most units, the amount of clutch slip and the point at which the slip initiates can be adjusted by changing the rate of and the preload on the clutch springs. Another method is similar to the old racer's trick to reduce engine braking by increasing idle, and current electronics systems slightly open a ride-by-wire throttle on deceleration. These systems can offer anything from a simple 1-2-3 level of adjustment to fully variable engine braking based on rpm, gear position, and more.
In series that don't allow elaborate electronics for engine braking control, however, we have to look to the chassis and ways of adjusting rear tire load in order to control how the motorcycle behaves on corner entry as the rear tire slips. In general, with more load the rear end will track straighter entering the corner, with less it will kick out more sideways. One way to address this is to raise or lower the whole bike, which affects how much load transfers under braking; with the motorcycle lowered slightly, for example, less load transfers to the front on corner entry and the rear tire stays more in line.
Another option is to make changes to the rear suspension to adjust the rear tire's reaction to a given load, rather than trying to adjust the amount of load. As an example, consider a rear shock setup with an amount of preload such that it takes 20 kg of load to even move the suspension; under braking, the rear tire will begin to skip and float across the pavement and go sideways if load goes below that 20 kg, because the suspension is topped out. By adjusting the spring rate or preload, we may be able to change that value so that the suspension begins to move with less or more load, altering when and how much the rear tire skids. Going a step further, we can even get creative with the top-out spring inside the shock to make that adjustment and influence corner entry behaviour without affecting the remainder of the suspension travel.
It all becomes a juggling act, with the slipper clutch, electronics package and suspension setup each playing a part. In an ideal setup, the bike backs into the corner just the right amount without requiring those precise clutch and rear brake inputs, allowing the rider to focus on more important aspects of the corner entry.
- By Andrew Trevitt
Friday, 27 May 2016 17:47 Published in Andrew Trevitt
I guess the best way to start this blog is with a simple “Welcome to my latest adventure.” After what feels like a lifetime of riding on the streets, in 2016 I am heading to the racetrack in search of an outlet that can satisfy a desire for speed and the accompanying adrenaline rush. It promises to be an exciting season, but as I found out right away, challenges are waiting around every corner.
It seems that with every project I work on there are always certain milestones, including the one that can only be described as the “What in the world made me think this was a good idea” moment. Shortly after deciding to expand my riding to include track days and road racing, that point arrived with striking clarity.
In theory my plan was anchored on a sound decision that some may even call “mature” or “prudent.” However, it turns out that there is a lot more involved with avoiding the speeding tickets and potential danger that awaited me if I continued to push the limits of riding on the street, than simply going to the track. As I contacted a few of the subject matter experts I have been fortunate to meet during my tenure at Inside Motorcycles, the questions and options that they laid out for me were more involved than anticipated. Do you want to stick to track days, or do you want to try road racing? Do you want your track bike to also be street legal? Do you have the right gear? Which tracks do you intend to go to? How will you transport your bike? Not only was the list seemingly endless, but every decision also led to a whole new set of decisions that needed to be made. As much as it would be easy to defer some of them, the reality is that the track season in Canada is short and time spent wallowing in indecision will ultimately eat away at the opportunities to ride.
Ignoring decisions and failing to do your homework can have even worse repercussions. Unless you are fortunate enough to live beside a racetrack, heading out for a track day or a race is going to involve loading up your motorcycle, all of your gear and an assortment of tools. Once you finally get to the track, do you really want to find out that your gear doesn’t meet the safety standards or that your motorcycle isn’t allowed? For experienced racers and track day riders, all of this is second nature, but for a newbie, there is no substitute for research and preparation.
Over the next few months, this blog will document the highs and lows of my experience as I work towards the goal of participating in multiple track days, attending a race school and hopefully competing in a couple of races. Along the way I will try to share some of the issues as they come up and how they were handled. As someone who is more comfortable with a camera than a wrench, it is safe to assume that I won’t be offering advice on how to set up a motorcycle to compete in a CSBK race, but if you are interested in a first-hand experience of the racetrack from a unique perspective, stay tuned. It promises to be fun.
- Patrick Lambie
Friday, 29 April 2016 12:05 Published in From Street to Track with Patrick Lambie
In previous blogs, and in the print version of the magazine, I have discussed anti-squat and how it relates to chassis setup. Anti-squat is a very important tool in making a motorcycle lap quickly at the racetrack, especially a powerful superbike, but at the same time it's one of the least understood setup parameters.
Some people claim that the rear end of the motorcycle must always compress, or squat, under acceleration to properly transfer load to the rear wheel for better traction. Others claim that the rear suspension must extend under acceleration, to "push" the tire into the ground and increase traction. People in the second group point to the experiment of putting the front tire of the motorcycle against a wall so that the bike can't move; when the clutch is gently released, applying power to the rear tire, the suspension extends significantly. But what really happens when the motorcycle is on the road or track and accelerating?
Here is what we know about anti-squat in theory: The three forces involved in compressing or extending the rear suspension as the motorcycle accelerates are the driving force, chain pull, and load transfer. Driving force refers to the rear wheel pushing the motorcycle forward, and generally acts to extend the rear suspension because of the swingarm angle. Chain pull is the force of the top run of the chain on the rear sprocket, also trying to extend the rear suspension under most conditions. And load transfer refers to the additional weight on the rear suspension due to acceleration.
There are a couple of key points to consider here: First, the load transfer component will occur whether or not the rear suspension compresses; in other words, acceleration will add weight to the rear wheel even if the rear suspension extends during that acceleration. The attitude of the motorcycle does affect the amount of load on the rear wheel, but to a very small extent. Second, the experiment of putting the front tire of the motorcycle against a wall removes load transfer from the equation; the rear suspension rises because only the chain pull and driving forces are present, the forces which serve to offset load transfer - which is eliminated here because the motorcycle is not accelerating.
Sum the three forces, and the math shows that the anti-squat effect decreases with more suspension travel, mostly because the swingarm angle changes through the stroke. At the top of the travel, acceleration will cause the rear end of the motorcycle to rise; at a certain point, equal to approximately the static sag setting on many bikes, the forces sum to zero and the suspension will neither compress nor extend on acceleration. As suspension travel increases, the anti-squat effect reduces further and the rear end will tend to squat on acceleration.
What happens in practice? Data that I have from Jodi Christie's superbike shows that in some corners, the rear suspension compresses during acceleration; in others, it extends; and in others, it remains constant from the moment Jodi applies the throttle to the end of the succeeding straight. The amount of compression or extension depends on traction, camber, elevation changes, and any number of variables.
The takeaway here is that, by adjusting various setup parameters as they relate to anti-squat, we can make the rear suspension do what we want on corner exits - extend, compress, or remain constant. This is usually a compromise to find a setting that works for the entire track, and we most often look at rear suspension in conjunction with other data, not on its own, for guidance on what that compromise should be.
Friday, 01 April 2016 15:25 Published in Andrew Trevitt
I started butchering some Sinatra the other day.
If you've ever heard me sing you'll know it was a good thing I was outside in the driveway, alone.
"And now, the end of winter is near,
And so I face the final snow shoveling
Friday, 11 March 2016 12:28 Published in Touring Essentials with R. Bruce Thomas
Over the past several seasons of MotoGP, Ducati has occasionally experimented with wings on the side of the Desmosedici to influence its aerodynamic characteristics. Yamaha also used wings in the latter part of last season on the M1, and wings have sporadically appeared on other bikes in the past. Until late last year the wings in use have been quite small, but during testing this year the Ducatis have sprouted two very large wings on each side.
Friday, 26 February 2016 17:21 Published in Andrew Trevitt
The Rocky Mountain Motards are in their second season at North Star Raceway, the new kart track in Strathmore, Alberta. President Jim states that they are very excited to have Zero Motorcycles as a new sponsor. “The world’s largest seller of full-size electric motorcycles has blessed us with help to reduce our track fees and try to have more people... involved in our exciting sport.”
Tuesday, 09 February 2016 16:41 Published in Supermoto blog with Keith Fowler
When it comes to endurance racing, you never know what you will have to deal with until the checkered flag is out. I have seen pretty much everything, and what I haven’t seen for myself I have heard about from friends or other teams. You can nearly destroy your superbike, rebuild it, and finish in the top five in a 24-hour endurance race. The secret to success? NEVER GIVE UP!
Tuesday, 02 February 2016 12:19 Published in Dan Kruger
What’s on your bookshelf?
It's cold and miserable outside. Your bike has been parked for two months already, and many more months will go by before you are riding again. How do you pass the time?
Pick up a good book.
Since you ride, that tells me you are a bit adventurous, which also tells me there is no point in me giving you my views on these or any other books. You’ll go exploring and find the ones you like.
No matter what kind of riding you like to do, there is a book you can find that will hold your interest. If you want tales of adventure from people who have travelled around the world or personal memories or spiritual growth found on the seat of a bike, you will find a book.
There are books by some very famous people and there are books about famous people. Some relative unknowns sell their self-published books at the bike shows over the winter and some books are only available from specific websites.
Support your local author.
There are books to help you develop/improve your riding skills, which can be quite helpful so sit back and reflect on the content as you await that first ride in the spring.
You can read about racers or get to the bottom of the long-distance rider mentality.
There are books filled with photos and there are books you will want to read for the articles.
Plus, don’t forget your favourite magazine.
Just because there is snow outside and you can’t go for a ride, there is no reason to forget about riding.
What’s on your bookshelf? Here’s a selection of what is on mine (see photos above and below).
Plus, your local library can quite likely get you any/all of these and more.
Read responsibly and enjoy your literary travels.
- By R. Bruce Thomas
What’s on your bookshelf?
Friday, 22 January 2016 11:13 Published in Touring Essentials with R. Bruce Thomas
We know that riding smoothly is one aspect of quicker lap times at the track and being safe on the street: Gentle, precise throttle inputs, fluid body movements and steady lean angles mid-turn are just some of the characteristics of what you'd consider a smooth rider. Jorge Lorenzo is a perfect example, with a glass-smooth riding style that looks like he is going much slower than he actually is.
Friday, 11 December 2015 12:16 Published in Andrew Trevitt