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Elbows
Your biological shock absorbers

By: James R. Davis



In addition to the shock absorbers you are already familiar with (front wheel, rear wheel and steering damper), there are two more that are very important to you as a motorcycle rider - your elbows.

In order to allow these shock absorbers to work you must not lock them. That is, you must droop your elbows while you ride. By drooping them you accomplish the following:

  • They remove pressure from the wrists and allow a longer more comfortable ride


  • They stop the transfer of front-end instability to the rest of the bike


  • They minimize the transfer of load to the front-end during hard braking (leaves it lower and farther to the back of the bike)

If you ride a motorcycle which requires that you lean forward over your tank, you already know that a long ride numbs your wrists and causes your forearms to ache. You know that you must lean even farther forward in order to unlock your elbows when you are about to take a bump with the bike.

Touring riders sit on their saddles in a generally erect posture, often with a backrest that they lean into while riding. If that backrest is too far back they will be forced to ride with their elbows essentially locked in order to reach their grips. If so, they will suffer the same numbness and aches after a long ride - it's not the posture so much as the stiff elbows.

If you have ever had your front-end wobble on you after hitting something in the road, or if that front-end is generally unstable (weak or badly adjusted steering damper), or if you have ever ridden over 'rain grooves', you know that if your elbows were locked you transmitted the instability of the front-end to the rest of your bike and made the entire motorcycle unstable. Drooped elbows absorbs all of that instability and leaves you in more control of your motorcycle.

You also know that braking causes a load transfer towards the front wheel. With the phenomenally powerful brakes we have today coupled with the newer tire rubber compounds, it is now possible for many bikes to literally raise their rear wheel off the ground in a panic stop. This is called doing a 'stoppie'. Drooped elbows will almost certainly prevent a stoppie from happening.

Assume that your elbows are locked solid and that your upper body is held in place relative to the handlebars when you apply the brakes. The momentum of your body transfers load to the front wheel during the panic stop. Your body, because of the locked elbows, does not move forward (relative to the rest of the bike) at all.

On the other hand, if your elbows are drooped, your upper body moves forward (bending at the waist and elbows) during the stop. Any such displacement of your body 'absorbs' the load transfer and keeps it local - the front wheel does not get immediately loaded (with a shifting of your upper body weight) as a result.

[Not to put too fine a point on it, but the real difference is in how much and WHEN the load transfer (from momentum) takes place -- how fast it happens. Rather than exaggerating a panic stop and dramatically compressing your front springs, your drooped elbows allows a smaller part of your upper body momentum to be 'felt' in the front-end gradually. For the purist, the way you determine weight transfer is to calculate the ratio of the height of your Center of Gravity (CG) to your wheelbase and multiply that by your braking force. Because your CG lowers when you lean forward, there is less weight transfer at any given deceleration rate. See the tip later on entitled Weight Transfer for a complete discussion.]

Copyright © 1992 - 2021 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)

     
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