Featured Learning about suspension in a methodical way.

Hi All,

Whilst reading through the threads I saw a few questions about handling and suspension set-up and thought that I could share with you how I go about it.

Before I get into this I should say that I am not posing as an expert, what I am about to say is an amalgam of experience, reading about these matters and the input of other more experienced than I.

The intention is to help those who are interested to learn about their suspension in a methodical way so that they can apply it to any motorcycle they may own.

Here goes.

1. Tyres.
   1. Before we start to make changes to ride heights, preloads, compression and rebound adjusters we should have a new, or very recently installed set of tires on, ie. no wear.
   2. The tire should be suitable for the bike, such as the tire the manufacture initially installed on the bike, or something very similar in terms of profile and weight.
   3. Tire pressure should be considered carefully and I would generally suggest towards the bottom end of the manufacturer's suggestions. Naturally the weight of the rider needs to be considered. My personal preference has been between 32-34psi on the front and 34-38psi on the rear on bikes of around the size, weight and style of the Speed Triple.
2. Sags. Unless you are very tall or short or heavy or light the standard springs should work for you.
   When doing this be mindful of the front fork stiction issue, so take an average measurement here. You will need help with this process.
   Keep in mind that preload is for adjusting sags, if you can't get the sags to work for your riding weight then you need to change your springs.
   Here is a link to the Ohlins .pdf manual that explains the process – see page 10. Keep in mind that althought this is an Ohlins document the pricipal is the same for all shocks/forks. http://www.oehlins.ch/data/122884090707242-01_OM_TTX36MCRT.pdf
3. Damping Initial.
   1. Front. I suggest that in your garage that you take off all front damping and then roll the bike forward and pull the front brake on. The forks will dive very quickly, then adjust the compression to the point that their dive has been slightly reduced. This means that we are now on the edge of the compression damping working. I would then wind the adjuster all the way in and count the clicks or turns and part thereof - write it down. Now wind the adjuster out the exact number of clicks or turns that you counted.
      Now do the same with the rebound, remember that we are only wanting to find the point that the damping starts to work. Write it down and then back it off the exact amount that you wrote down. So now you front compression and rebound valves are just starting to work. It would now be interesting to compare these damping adjustments with the manuals and see what the difference is.
   2. Rear. Turning our attention to the back of the bike, sitting astride the bike take all your weight off the bike and then sit heavily on the seat and feel the ease at which the shock moves. Adjust the compression as with the front until you notice a slight change in the rate it moves - wind the adjuster all the way in counting the clicks etc. and recording. Then wind the adjust out the recorded number of clicks or turns. Do the same for the rebound - I'm sure you get the picture.
4. Test ride. With the compression and rebound damping very lightly set you will be able to feel the springs work and that their performance isn't being masked by overdamping. Be careful here, start of slow and be smooth on a road you are familiar with. By smooth I mean no hard braking, acceleration or fast direction changes. Gradually increase you speed and think about how easy or hard the bike is to turn into a corner or hold in a corner. If you feel it is perfect, then you can skip points 5 and 6.
5. Pitch. We all have different riding styles and so the pitch of the bike can be adjusted to meet our personal riding preferences. For example if you like to lean forward and off towards the low side when cornering you'll prefer a different pitch to someone who just likes to stay in line with the bike's centre.
   
   On bikes with a rear ride height adjuster this is easy to play around with. Although mostly it will need to be adjusted by slipping the forks through the yokes.
   Example: If you feel you need to lean off the bike more that you’d like then you could consider sharpening up the handle a little by sliding the forks through the yokes.
   I would suggest that if you are to play about with the pitch you should not slip the forks through the yokes by any more than 5mm at a time. Believe me that 5mm will have a very noticeable effect, ie. it will sharpen up the handling quite markedly. So be careful on your test ride, it will be different. If you are concerned then only make a 3mm change.
   When making this adjustment you must make sure that all the weight is off the front forks, this may sound obvious but people do make this mistake.
   From a racing point of view there is a tendency to get the sags set correctly, then the pitch and then they try and lower the bike as much as possible but maintaining the previously established sags and pitch. Clearly this is to get the weight as low to the ground as possible and therefore improve the bikes ability to change direction.
   Here is an interesting article that explains rake and trail that you may find worth reading: http://www.motorcycle-superstore.com/4125/mngr/rake-and-trail-explained.aspx
   1. Test ride. Once again, be slow and smooth on a road you are familiar with. Gradually increase you speed and feel the effect of change. If you like it, great you can keep it, or increase of decrease the amount of adjustment. This time if you want to increase the effect then I would only make an adjustment of perhaps 2mm, certainly not 5mm again. Test and adjust as required.
      When you feel the bike is pitching in to the corners and holding the line nicely with your riding style then we are ready to move onto damping.
6. Damping Final.

So now we have the sag set, the pitch set and the very lightest of compression and rebound damping set. Time to hit the road again. You will need your pen and paper and the appropriate screwdriver(s). You will need to record everything you do.

This is another subjective bit, much like the pitch. Go back out to your favourite stretch of road and ride it smoothly and slowly at first building speed gradually, take you time with this.

When you feel the bike doing something you don't like you need to stop, think about what you felt and make an adjustment - write it down. Keep in mind that sometimes what you feel can originate elsewhere on the bike. For example, if we don’t have enough rebound or compression damping on the rear it will tend to wag the front. So, I suggest that the you may want to increase the rebound on the rear first if you are experiencing a front-end stability issue.

NOTE: when making an adjustment only change one thing at a time and make a big change so you can feel it.

Once you’ve made a change try it out by once again being smooth and slow and building speed.
Did your adjustment make it better or worse? If your adjustment made it better, then try backing off the adjustment to half of the initial adjustment and see if it gets any better or if the initial problem returned. Just because we found a setting that fixed a problem doesn't mean to say that a milder setting may have fixed it better.
If the adjustment didn’t improve the issue then undo the adjustment and try something different – write it down

What we are trying to get to is the settings that are the least intrusive and that let the springs do their thing and give you the stability and feeling that you need.

Generally, I would say that most (but perhaps not all) suspension people feel that rebound adjustment is the first of the damping settings to be adjusted. Although it is fair to say that compression and rebound need to work in concert. So, some compression damping is required when working with rebound.

Try working with the rear rebound first and see what that does for you, then move to the front rebound. If you start to approach the max rebound settings listed in the manual, then try adding a little compression damping and if that gives you the desired effect.

Braking. Front compression adjustment is often geared to limiting the dive speed of the front during heavy braking and therefore reduce the risk of bottoming out etc,

NOTE: If you are doing this over multiple days then you must check and if necessary adjust your tyre pressure each day you go out. Even a 2psi variation can throw you out.


A final point, if you get a little muddled during the Damping Final process go back to Damping Initial and start again. This is all about the learning, getting a great handling bike is a by product of that. If anyone has any other thoughts on this subject I am very keen to hear them, always looking to learn more about this black art.

Cheers,

Graham

 

Thanks for your comments. I would be keen to hear how any of you progress with suspension adjustments.