Breakdown: Season of Changes

Breakdown Season of Changes

June 17, 2014 4:20pm

Lately there has been a lot of talk about the changes that riders and teams make to the motorcycle. These changes can happen during the week, after practice or between motos. The changes are almost always at the direction of the rider but team personnel plays a crucial role as well. My hope is that the next time you hear a rider on the podium say “we went the wrong/right way with bike and it made a huge difference”, that you will have an idea of what they mean.

The top riders have a number of options at their disposal. From tire choices, clamp offsets, different races inside the steering stem, ECU settings, linkages, and fork and shock settings, there are multiple ways to improve or worsen your bike. At times, having so many possible settings can be a bit overwhelming but when the bike is not doing what you want it to, it’s definitely nice to have options. But trying to perfect a setting at each track is tricky. Small changes can have drastic effects in handling and hence rider comfort. The toughest challenge is predicting what impact that one change will have on another part of the bike.

Let’s make an example: Rider A is at a track with a lot of hills. Coming down the hills, all of the weight is transferred to the front end. That weight is going to compress the fork more than it typically would, making the front end feel soft and unbalanced. That in turn will lessen the rider’s confidence to increase speed while descending for fear of hitting a large bump, having no travel left and thus going over the bars. To counteract this, there are a few choices. The simple answer is to increase the compression in the fork, making it stiffer and more resistant the weight transfer. The fork will stay higher in the stroke and push back against the shock. Easy enough, right? Not so fast. Stiffening up the fork for the downhill may have an adverse effect on other sections. The stiffer the fork, the harder it is to turn the motorcycle. The “feel” that riders are always looking for in the front end will start to deteriorate as you go stiffer and stiffer. Front end traction is lessened as well, and there’s less absorption and plushness over small bumps. For a rider like Mike Alessi, who loves his front end to be a bit soft, this can be a tough tradeoff. Mike wants his front end to settle and drop into the stroke so he can turn on a dime and really feel where he is putting the tire. A stiff fork, say what James Stewart likes, really makes this difficult.

Changes are almost always at the direction of the rider but team personnel plays a crucial role as well, says Jason Thomas.
Changes are almost always at the direction of the rider but team personnel plays a crucial role as well, says Jason Thomas. Photo: Simon Cudby

So, what’s another option if going stiffer isn’t viable? Enter the world of clamps and races. The clamps and the races inside the steering stem are good ways to change the angle and geometry of the motorcycle. The clamps essentially move the forks forward and backwards while the races change the pitch of the fork angle by changing the angle of the steering stem inside the head tube. Both are great tools to test with but it’s also very easy to get lost in a sea of settings. With multiple clamp options typically from 18mm-24mm and a plethora of options with the steering stem races, these combinations can become a labyrinth of setup. Remember, every change has both a direct result and then compromise in some other aspect, so it becomes extremely complicated to find something ideal. If Mike Alessi went from a stock Suzuki clamp setting (21.5mm) to a 24mm clamp in order to get more confidence on the downhill, he is certainly going to notice the feeling of the longer wheelbase that setting creates. The bike will become much more stable in the rough bumps but will turn about as accurately as Grave Digger. To compensate, he could then move the races, but it’s tough to find the perfect combination. Maybe the solution was to just start with the races and then try clamp offset later? As you can see, it’s a never-ending set of checks and balances when trying to correct a handling problem. One solution leads to another problem and round and round we go.

Keeping detailed notes on each setting and change is crucial to avoid chasing your tail, so to speak. I have been through this a time or two and it’s common to make 30 changes throughout the day and then have no recollection of what was good or bad about a certain setting. It’s no easy task and requires a lot of patience, diligence and technical expertise from the team. So, as you can see, when a rider says they made a change to the bike and it made things worse, it could literally be any number of things. It could be that his bike wouldn’t turn how he wanted. It could be that it wouldn’t handle the rough, nasty bumps well enough to just turn the throttle up when he needed to. It could be that the track conditions changed and he chose the wrong tire for the second moto or main event. It could be that he adjusted his “traction control” too high or too low. Honestly, it could be anything. So the next time you hear, “We made a change and went in the wrong direction” I hope you have a better idea of what that means—it’s hard enough to understand, it’s even harder to fix.