" Generally speaking you do not need compression damping on the street because too much compression damping will give a harsh ride" Not Really.

" Generally speaking you do not need compression damping on the street because too much compression damping will give a harsh ride (the stock setup has no compression damping). "

I would like to explain why this needs context, as it really is not true.

This was referring to forks where it was posted, but it is the same for either forks or rear shocks.

If you were to have 2 identical bikes, and if both had THE SAME spring rates, and one had compression damping, and the other did not, the statement would be true.

Why is this? Because the compression damping is slowing the movement of the suspension, this slower movement feels like a harsher ride to the rider.

So why do all modern shocks and forks have compression damping if it makes it feel harsher?

The compression damping allows you to use a lighter rate spring, and a lighter rate spring WILL give you a better ride, this is why the statement is incorrect


You are now using the damping to slow the suspension movement, not the spring alone.

The way the damping works is also a huge benefit, the faster the suspension movement, the MORE damping you get, so a big bump, or a small bump at a higher road speed, produces more damping.

What are you trying to do with suspension?

In a perfect world, as the bike is ridden over bumps, the wheels via suspension would be the only thing moving up and down, the job of suspension is to keep the seat in the same place all the time.

We are not yet there.

Better suspension, controls the movement more, meaning the bike under the rider, MOVES UP AND DOWN LESS, this is really important, this produces not only a better ride quality, but a more stable bike, both in turns and straight line riding. As well as adding better traction, since the tire movement is better controlled, tire grip is improved.

Why else is it important to have less bike movement?

Geometry.

As the bike moves thru the travel the bikes geometry is changed.

As the rear swingarm angle is reduced you generally lose grip. as the rear is compressed, you gain trail. as the front forks are compressed you lose trail, so under braking, the more brake dive the less trail you have. a really good front form, will have a damping circuit, to help slow brake dive.

What is trail why does it matter?

Here is something I wrote up a long time ago to help you understand Trail

Geometry 101

Geometry Basics
Ahhh, geometry is complicated.
So many things have a direct effect.

Basics:
As the rear of the bike is raised you lose trail.
As you raise the front of the bike you gain trail.

Trail is the built in stability of the bike.
You want as little trail as possible, but you MUST have enough to insure both stability and the ability to STEER.

As you remove trail the bike no longer want to go straight, it wants to fall over or turn.
This is what happens entering a turn, the less trail the lighter and faster you can change direction.
But as you exit the turn, you are already leaned over and now are applying power.

Now you need to be able to hold your line, tighten your line or loosen your line, I call this the ability to STEER.
The two, turning and steering, are different.
If you do not have enough trail, as you exit a turn and apply power, your bike will push to the outside and the only way to stop it is to back off the throttle.

Other things that effect turning and steering, tire shape and construction. Weight and where the weight on the bike is. (Center of Gravity)
Wheelbase length.
Handlebar length and angle (leverage).
Footpeg length and location (leverage).
Suspension.
Gearing, you change ride height as you adjust the chain tension.

Just some notes:
As pointed out already when you change the Triple Tree offset, (the Ohlins guys hate when I say that they call them Triple Clamps), from say 36MM to 30 MM you are increasing trail, adding stability, making it harder to "turn in". But you are also reducing the wheelbase by that same 6MM, that is a lot!! On conventional swingarms you can usually add some wheelbase length back in

More stuff: all these numbers are appox.

a 1 degree RAKE change is about a 6MM change in trail

a 4MM rear ride height change (measured at the rear axle) is about a 1 MM trail change

a 4MM front ride height change is about a 1 MM trail change.

a 1mm offset change is a 1mm trail change and a 1mm wheelbase change.

Click to expand...

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Ah, thank you. I know you mean well. But, does this mean I need to radically modify my Commando’s suspension in order to have fun in the twisties? or is this about racing?

Welcome to the site, Dan. Excellent post.

I swapped out the Showa forks on my 996S and put Ohlin forks on and it worked pretty good with compression damping. Learned how to set up forks from riding off road for years. It helped a lot.

With my little Norton I rely more on the spring rate and oil I use. I'm using Betor forks and triple clamps that are not all that sophisticated, but probably better than whatever version of Roadholder forks Norton used. Really smooth ride with very little dive under braking. I almost read your post, but am BBQing and have to get back to it.

Hi Dan, Welcome.
That ramble was a bit random......
Are you a lurker who just couldn't stand the endless discussions on handling which oft times include bits of nonsense?

perhaps this thread belongs in in the "Motorcycle Related Discussions". Not much Norton content though I appreciate the interest value for many.

Modern forks have 2 or even 3 stage damping also called digressive damping, they have higher damping at low fork movement speeds of over smooth surfaces and then lower damping at high fork movement speeds. I have Showa cartridges with 3 stage compression and 2 stage rebound damping in my Commando forks. You get a firm ride over smooth roads but less effect from bumps as the damping drops as the form movement speed increases.