Another Motorcycle Suspension Thread

Help Support ClassicGoldWings:

Rednaxs60

Well-known member
Joined
Dec 25, 2015
Messages
2,475
Reaction score
69
Location
Victoria, BC,
Another suspension thread you think, well yes. It’s because it is near and dear to my heart, and one of the maintenance items I do up front whenever I get a new-to-me bike. I am investigating this issue because of my 2012 DL1000 VStrom. What I am learning; however, is going to apply equally to my GWs.

What I am presenting here can be found on the internet, in the various forums and in a plethora of motorcycle books/articles.

I have upgraded the suspension on my 1200 and 1500, but did so without a good understanding of the science behind what I did. My 1200 was done by a suspension shop that asked about myself, how and where I rode, solo or two up, and percentages. The suspension on the 1200 is dialed in quite well thanks to the shop that did the work.

My 1500 is not so lucky. I felt that I could do the bike justice so I did my own work. I changed the rear shocks to Progressive 416 air shocks, not much more can be done with this setup. The front forks got a refresh with new Progressive springs.

At present, the best ride is the '85 LTD. I do not feel any bumps and the setup (mostly luck) is quite good. The 1500 may get some attention, but I do not know how long it will be in my stable, thinking a couple of years at best – only have so much room.

I have learned from these bikes that not all suspensions are created equal.

I have mentioned in many posts that the suspension is the only item on the bike keeping the tires firmly planted on the road, and that ride quality and performance is directly related to the suspension. Reading and viewing videos have corroborated this. How this is accomplished is the issue I am now looking at. Up to now, my changes and suspension upgrades have been mostly by gut feel, and based on economics as well.

Tire longevity is directly affected by the state of the suspension and how it is setup. Proper suspension tuning is also a factor in how you feel after a day or days in the saddle.

I have three bikes and the suspension is different on each.

The 1200 has a good suspension setup in the front but to make any changes the forks have to come off and adjustment(s) made. The adjustments are compression dampening using the Race Tech Gold Valves, and preload can be adjusted with shims (larger washers). An upgrade that I would benefit from is changing the fork caps for adjustable preload fork caps so the sag could be setup without removing the forks. Compression dampening would still require removal and fork work to get at the gold valves.

The rear shocks are good, do the job better than the OEM air shocks, but only have a preload adjustment. This has worked well so far doing solo, two up and touring. The manual preload can allow for sag adjustment, but getting to the adjuster is a challenge. A remote preload adjuster would be nice as would compression and rebound adjustments.

The 1500 has been kept closer to the OEM setup. Changed out the front fork springs for new, no preload adjustment unless you take the forks off and add shims. This setup would also benefit from a change of fork caps to those with a preload adjustment. Proper spring rate would also be beneficial. The 1500 is a heavy cruiser and needs heavier springs than installed by OEM.

The rear shocks on the 1500 are the Progressive 416 air shocks. Both sides work the same unlike the OEM setup. Not much can be done here unless you want to install high end reservoir shocks that have all the settings that you would expect from such a shock.

The VStrom has an external preload adjustment for the front forks. This allows you to set the sag. The rear shock has a remote preload adjuster as well.

Armed with this knowledge, I have been scouring the internet and motorcycle forums for information regarding motorcycle suspensions, and proper setup depending on what you have available to you.

Suspension tuning is probably seen as a black art, of which it probably is, but it is by no means a monopoly by the suspension shops and/or those who do this work for a living. You can educate yourself to setup your motorcycle suspension so that your ride is much, much better.

The basics are:

Suspension sag: static (rider) sag, free sag – weight the bike exerts on the suspension;
Damping: controlling the oscillation of the suspension while the suspension is being used;
Compression: control of the suspension downward stroke;
Rebound: control of the upward movement of the suspension after the suspension has been compressed;
Stiction: resistance of the suspension parts/pieces to movement; and
Rake/trail: design aspect of the motorcycle, but changes ever so slightly by suspension changes.

The first step to tuning the suspension is to set suspension sag. On my 1200 and 1500, front fork sag is what it is because there is no external preload adjustment. To change what is there would require fork work to shim the internal spring more or less. This is not going to happen at this time, but I am now keenly aware of it. With this also comes the fact that front suspension compression and rebound tweaking is off the table as well. Since all front fork components are in good condition, damping, controlling front fork oscillation, is not an issue.

The VStrom is another issue in that I am looking at it from a new perspective, that of what has to be done to improve the OEM suspension.

I am aware of the companies that specialize in new aftermarket suspensions such as Traxxion, Race Tech, and Progressive to name three of the most popular. There are a number of other companies such as DMr Performance Suspension, and Adventure Tech that specialize in suspension products and tuning to name a couple.

We here in Canada have a few available to us, but not as many as in the USA. There is a company in Abbotsford, BC – RMR Suspensions, and Accelerated Technologies in Ontario.

There are choices, just have to do your homework.

Your budget will determine what you do as well. Suspension upgrade(s) are not inexpensive, but it depends on what you want to achieve.

High end rear shocks can be upwards of $2K, and similarly for the front forks with cartridges. What are the road conditions where you do the majority of your riding. Solo only or two up and touring. If riding two up, the pillion had better be happy or your ride will not be as enjoyable.

How long will you keep the bike is a determining factor, as is where you ride. Here on Vancouver Island main roads are not too bad, but some of the secondary roads such as the road to Port Renfrew from Victoria is riddled with bumps, dips and such that can cause a cruiser to bottom if you are not careful.

Another issue that suspension specialists comment on is shock heat. As the shock oscillates it produces heat, and heat is not a friend to a shock. Oil thins out, if you have an emulsion shock – the oil and nitrogen charge are in the same chamber, the mixing of the two fluids because of the heat generated can cause the shock to not perform as expected. Some manufacturers will offer a hydraulic preload adjustment on its lesser expensive shocks – additional cost, and/or a rebound adjustment.

A reservoir shock that has a remote or integral reservoir – non adjustable – is the next best in that the nitrogen charge is separated from the shock oil by a bladder. This type of shock has more oil in the shock case than the emulsion shock and the nitrogen charge cannot mix with the shock oil.

The best of these three types of shocks is a fully adjustable reservoir shock with a remote or integral reservoir. The tuning of this type of shock generally includes hydraulic preload adjustment – integral or remote, rebound adjustment, compression adjustment – high and low speed.

Have a good look at the suspension on your bike and determine what suspension you have and what suspension tuning adjustments are available.

There is a plethora of aftermarket front fork and rear shock upgrades available to us. As with all parts, determine your needs, budget, and then look for the best bang for your dollar. Must mention that you should educate yourself about suspension tuning even if you would go to a suspension shop to have the work done.

There are some low-cost fixes that may fit your riding style as well. The one that comes to mind is a new front fork cap to allow for externally adjusting the fork spring preload. Doing this could get me a ½ inch of preload adjustment, and make a considerable difference especially if the sag can be brought into the proper range. I am considering this for my 1500. I could also look into new fork springs that have a greater spring rate. Could change from a progressive style spring rate to a straight spring rate as well.

I mentioned earlier that suspension sag was the first suspension setup that should be done. On a cruiser such as my 1500 there is probably 3 or so inches of front suspension travel. The industry standard is for a rider sag of approximately 30% - 25 to 30 mm of the overall travel. This doesn’t leave a lot of room for adjustment. In this case fork spring rate is very important and getting as close as possible to the correct spring rate so that at zero preload you are in the 25 to 30 mm sag ball park is quite important. A discussion with a company that deals in and supplies front fork springs would probably be beneficial.

The only change I am contemplating with my 1200 is changing the rear shocks. I would stay with the non air shocks but would probably look into a reservoir shock with a remote hydraulic preload adjuster, remote reservoir with high/low speed compression and rebound adjustment. I’m going to chew on this for a while, but since this is my retirement project, and the one I will keep instead of the 1500, should probably start saving for the inevitable. Might even look at the front forks as well. Have 40K Kms on the new suspension since install.

The OEM air shocks have an eye to eye distance of 13.75 inches. The aftermarket Progressive series 12 non-air shocks installed are 14.5 inches eye to eye dimension. The additional ¾ inch of shock height has/does not impact on the bike performance; however, when the bike is on the centre stand, the rear tire touches the ground.

A lot of you older crowd, dirt bikers, street/track racers out there are probably snickering at my revelation with respect to motorcycle suspension. I know I’m not alone in understanding motorcycle suspension, but in my defense, I would like to say – better late than never.

When looking for a new ride, take the time to find out what suspension is on the bike being considered and what suspension adjustments are available on the specific bike. You may be able to find a bike that fits/suits your requirements in your price range that has a good suspension that can be tuned to your specific riding requirements/capabilities.

If you have read to this point, thank you for your perseverance. I’ve put this novel together more for myself than anyone else, it is how I formalize my thoughts, and put together a game plan for the way forward. I will be delving into this further, to further my education on motorcycle suspensions, and intend to apply what I am learning to all three of my bikes depending on how each is classified – specifically staying/going.

More to follow.

Cheers
 

joedrum

Well-known member
Joined
Dec 8, 2009
Messages
19,374
Reaction score
5
Location
chuluota florida
Hmmm for systems that are rather basic ...the cost of things get in the insane area ...I’m no papered engineer ..but I know how things work ...I think I could put together a set of front forks that could beat anything out I’ve seen ...it amazes me how screwed up the designs are ...and over dependence on parts that are going to fail by design ...
 

Rednaxs60

Well-known member
Joined
Dec 25, 2015
Messages
2,475
Reaction score
69
Location
Victoria, BC,
Hope you used the read to get some sleep. Reminds me of a friend of mine when I was in our Navy. He was a Combat Systems Engineer in charge of the weapons systems on board. He decided to have a go at the formula for projectile motion - firing of the gun and how the bullet would travel through the air to target. He worked on it for 6 months, and every time he would get to a certain point in the equation and hit a brick wall - could go no further - start again on a different tact. In the end he capitulated, and accepted what was.

I think suspension is the same. If you have the tools and parts, can determine the inherent design elements of the parts, you can have a go at it and have fun in the process. I'm a believer in accepting most things that have been developed and accepted by the industry, in this instance racing. The racing industry tests/trials different concepts and the results are passed down to us mere mortals on the street.

The OEM does have a different priority than we do, cost benefit. We want items/parts/pieces to last for a long time and do a good job. The OEM wants to design and produce a product that will do the job, and do it well, but looks at a very short time line for longevity, after which we the consumer should upgrade and buy its product again.

Having mentioned the above, having fun and learning in the process. Looking into suspension, an ECU upgrade/replacement for my '85 Limited, sorting out the TPS on the '85, and a few other small projects is keeping the gray matter stimulated.

Cheers
 
Top