Suspension Understanding – The Skiing Philosophy

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Rednaxs60

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Been thinking about another topic near and dear - motorcycle suspension.

I have been trying to think of a way to understand the nuances of motorcycle suspension setup – preload, compression and rebound. I have read books on this such as the one from Race Tech, and watched a lot of suspension videos.

I came to a possible understanding this morning while answering a question about preload. Relate motorcycle suspension setup/settings to skiing. Everybody likes a good story. I was a certified Level II CSIA instructor back in the ‘80s.

Preload is easiest of the three aspects to understand. You use preload to level the motorcycle, taking into account the motorcycle weight and the main riding aspects such as solo /two up riding, and luggage.

You want the motorcycle to be reasonably level in all riding conditions. Straight running, cornering, going uphill and downhill. This is similar to skiing in that you want to keep your body perpendicular to the hill you are on. You also want to keep a quiet upper body, and maintain the same head height above the snow.

Shock rebound and compression is a little more complicated.

Rebound is how fast or slow you want the shock to return to its normal, unaltered state. Think about skiing a “green” easy run. Not a lot going on, very smooth and forgiving. Move up to a “blue” designated run and the shocks – your legs, need to start to do more work. The legs start to absorb more of the undulations, and sometimes encounter a dreaded mogul or two. Move up to a “black” diamond run and your legs need to start to perform, this is because you are probably encountering a multitude of moguls of varying sizes.

What has to happen on a “black” diamond run is the rebound aspect of your shocks, aka legs, is that the legs have to extend into the trough between moguls to keep the skis in contact with the snow. Doing this too fast will jar your body and throw off your rhythm. Extending your legs too slow will make your skis loose contact with the snow and when the skis hit the bottom of the trough, your legs will compress to absorb the additional force from the landing. Both scenarios upset the balance between preload, rebound and compression.

Compression adjustment is the same but in the reverse. You have maintained your preload, distance of the head above the snow, you have adjusted your rebound to ensure that the skis are always in contact with the snow as you transition from the top of the mogul and ski down into the trough, not too fast, not too slow. Now you have to transition to going up the front side of the next mogul.

Compressing your legs too slow and you will launch yourself off the top of this mogul. If done on purpose it’s really quite fun, but the goal is to maintain control and keep the skis in contact with the snow. Compressing your legs too quickly and you will tend to lose ski contact with the snow, and “slam” into the mogul losing speed, and upsetting your rhythm. What you want to achieve is a leg movement that keeps the skis in contact with the snow, and the preload, your head height maintained.

How does this analogy of skiing relate to motorcycle suspension? It’s all about keeping the tires in full contact with the road, and maintaining a smooth, enjoyable ride.

Preload is easy, set to the primary riding mode and adjusted, if possible, to suit other riding profiles.

Rebound and compression settings are a “feeling”, much like skiing; however, in skiing you adjust to the terrain you are on, on a continual basis. Rebound and compression settings on a motorcycle shock are generally set to a specific setting that covers the majority of the road riding being done. This entails a systematic program of trial and error until you “dial” in the rebound/compression settings to suit your riding style and primary riding area.

I was told by a riding course instructor a few years back that motorcycles do not like to have the “balance” upset during a ride. This could be on a corner, or any other time during the ride. This could also be from not being on/off smooth with the throttle. What ever the reason for an imbalance in motorcycle performance, we should try to minimize it so that we optimize the motorcycle performance.

Motorcycles now have electronic systems that continually adjust the suspension to adapt to road conditions, and to give the best possible ride. These systems emulate the art of skiing.

Now that I have confused the whole aspect of motorcycle suspension, where will I go with this. I bought my ’85 Limited Edition as my long-term retirement project, to enhance my understanding of what I ride and how I can make it better. With this in mind, I will be looking into what I can/could do to the suspension of my ’85 Limited Edition to enhance the already not too bad ride.

This will probably entail determining what the sag should be, what front suspension options available, and maybe installing a new front fork suspension.

For the present I will concentrate on dialing in the rear suspension.

Cheers
 

pidjones

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Add to that the huge advance in tire technologies of the past 3.5 decades. The drawback being that fitment of the newer tires that fit and will handle the weight of a GL is getting limited. You might contact Traxxion Dynamics in Woodstock, Georgia to see if their AK-20 cartridges can be fitted to the front forks. Fork braces and billet tripple trees are another way to tighten front end feel.
 

Rednaxs60

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[url=https://classicgoldwings.com/forum/viewtopic.php?p=222262#p222262:2nh2b36k said:
pidjones » Today, 3:33 am[/url]":2nh2b36k]
Add to that the huge advance in tire technologies of the past 3.5 decades. The drawback being that fitment of the newer tires that fit and will handle the weight of a GL is getting limited. You might contact Traxxion Dynamics in Woodstock, Georgia to see if their AK-20 cartridges can be fitted to the front forks. Fork braces and billet tripple trees are another way to tighten front end feel.
I did talk to Traxxion early last year about 1500 fork cartridges. These are available. Traxxion did mention that it had fork cartridges for the 1200 as well - have to confirm. My order of preference has always been suspension upgrade, then the external additions such as fork braces and a triple tree. I installed the Traxxion "full monty" on my ex-1800 when I first bought it. Significant difference in handling and performance. The install came with the updated triple tree that was more robust than stock.

The simpler option is to install new fork springs, thinking Sonic straight rate springs - 1.1 kg/mm or 1.2 kg/mm and install preload adjusters. Have the gold valves already installed. Just checked the sonic web site and its fork springs for the 1200 have gone up $10.00 USD.
 

pidjones

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[url=https://www.classicgoldwings.com/forum/viewtopic.php?p=222264#p222264:3pqs5u49 said:
Rednaxs60 » Thu Jun 03, 2021 8:58 am[/url]":3pqs5u49]
Just checked the sonic web site and its fork springs for the 1200 have gone up $10.00 USD.
Much less than the increase in lumber prices!
 
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