Motorcycle Wheelbase Overview
- From: TRS Media | Published: October 2nd, 2008 - 10:11 am
Wheelbase – What is it and why should I care?
The wheelbase on a Motorcycle is the measurement from the center of the front axle to the center of the rear axle. The length of the wheelbase affects how your motorcycle handles characteristics both in the corners as well as when your bike is straight up (or in a straight line.) The quick version is a longer wheelbase improves straight line high speed stability. This can be an advantage on bumpy tracks or on tracks with very high speed sections. It also has a positive effect on braking, especially when high speed hard breaking is required. The downside to the long wheelbase is that it can slow down the quick-turn-in or the ability to flick (change direction quickly) the bike from side to side. It can also have a negative effect on what I refer to as finishing a corner. By finishing I’m referring to the part of a corner after the apex when you are trying to get back on the gas, if your wheelbase is too long your bike will want to run wide. For example at a high speed track like Daytona the long wheelbase can be beneficial on the high banks but detrimental at the high speed chicanes on the back straight.
Adjusting the wheelbase can be done in several ways, some considerably easier than others. The easiest way is to use the rear wheel axle adjuster. This may entail carrying a couple different length chains but once you get the hang of it you’ll find it well worth the investment. Most contemporary sport bikes have anywhere from 15 to 25 mm of adjustment. It is also possible to change the wheelbase with the adjusters by changing the sprockets. Assuming you have a gear ratio chart for your bike you can manipulate the ratio between the front and rear sprockets to achieve the same final drive ratio while using a taller or shorter rear sprocket in order to achieve the desired result.
The second (or third depending on how you’re counting) option is to actually change the swingarm. This may sound crazy to some but it is a common practice at the professional level. The longer or shorter swingarm has a similar effect to moving the adjuster with one key difference. If you go to a longer swingarm you will experience greater stability when sliding the rear wheel of the bike. This is extremely advantageous when exiting corners hard on the gas in a high speed bumpy turn.
The thing is, you should try some different settings so that you can feel the difference for yourself because adjusting the wheelbase can change your handling significantly over an entire lap. All tracks will present the need for some compromise but the compromise that gets you from point A back to point A the quickest is the right one. Every 10th of a second counts when you’re running at the front!
