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- Jul 16, 2020

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- 126

I have wanted to make an Ohlins shock fit the Commando/Roadster for a long time.

I am hoping to get feedback form people on the forum as to what you would want in a replacement shock.

Ohlins has been making them for the "New" Nortons since 2010.

While I was looking for info, I came across this forum, Lots of Good info, as well as some threads on Shocks and some pictures of various Ohlins Shocks on Bikes.

So I am going to give it a try.

First I learned a lot on this forum, the first issue was the fitment problem with the chain guard.

The OEM shock is very small diameter by today's standards., and on the Ohlins it is an issue. More on that later.

First things I had to get in order:

Know what is on the bike already

I have 4 Nortons, but only one is a "late" model one, (850 JPS)

So I have stock shocks.

Specs on the OEM Shock

OEM length 329 mm (Just shy of 13 inches.)

Stroke 83 mm

Width 18 mm top and bottom

Spring 22 Nmm Straight rate

Spring free length 224 mm

Installed length (preload) at "0" setting 213 mm

Installed length (preload) at "1" setting 205 mm

Installed length (preload) at "2" setting 198 mm

The Installed height, also known as spring preload, is the length of the spring when it is installed on the shock.

We like to see 15 to 30 mm preload on a twin shock set up.

We have a lot of Harley Davidson experience with twin shocks, some on /5, /6,/7 BMW's and Ducati Bevel drive twins.

With HD's a 1 turn preload increase (1.5mm) equals a 25 lb rider/passenger weight change.

This means if we set up a shock for a 200lb rider, and they add 25 lbs to the bike we increase spring preload by 1,5 mm or on an Ohlins shock 1 turn, 150 lb increase 6 turns, easy, right?

The chart is made on our Shock Dyno using an attachment that allows us to measure springs.

Check what weight that spring may work for by checking Rider sag

With a 209 lb rider:

At "0" preload Static sag 22mm Rider sag 47mm

At "1" preload Static sag 18mm Rider sag 38mm

At "2" preload Static sag 8mm Rider sag 29mm

What we shoot for is the rider sag at 30 mm and the static sag number is a check number, it should be between 5 and 15 mm

We will end up trying 3 different rate springs and see which ones work best for different rider weights.

if we need to try more we can, that part is easy.

18 Nmm, 20 Nmm, and 22 Nmm,

The lighter springs will require more preload assuming the rider weight were to be the same.

This means we could end up using a 18 Nmm spring with a 200 lb rider with a lot of preload, I suspect this is what we will find works best.

Next we ran Dyno tests on the stock shock, and as a comparison on one of the possible Ohlins shocks

I will post these later today, and explain what you are seeing in the charts, as without that they will not mean much.

Back to picking an Ohlins shock to start with.

There are a number of Ohlins shock that are close to that.

Not only does the length have to be correct the stroke, damping, spring rate, width.

We can change anything on the Ohlins shocks, but the closer they are to start with the easier it will be.

There are a few

SU143, Length 331 mm stroke 84mm Out of stock until Oct

DU140 Length 331.5 Stroke 93mm

HD159 Length (adjustable) 324 to 334 mm Stroke 77 mm

I am going to start with this shock, HD159.

This is one of a family of Harley shocks, Ohlins has these in Silver, or Black, with Black springs or Yellow, No chrome.

There are also versions with different part numbers with different features.

Ohlins has 3 versions in 2 colors for the HD's,

The 3 versions are at different price points.

The simplest only has an adjustment for spring preload , no damping or length adjustments (329mm)

The next version has adjustable spring preload, adjustable length, and adjustable rebound damping

The last version has adjustable spring preload, adjustable length, adjustable rebound damping, and adjustable compression damping

More later

Thanks

I am hoping to get feedback form people on the forum as to what you would want in a replacement shock.

Ohlins has been making them for the "New" Nortons since 2010.

While I was looking for info, I came across this forum, Lots of Good info, as well as some threads on Shocks and some pictures of various Ohlins Shocks on Bikes.

So I am going to give it a try.

First I learned a lot on this forum, the first issue was the fitment problem with the chain guard.

The OEM shock is very small diameter by today's standards., and on the Ohlins it is an issue. More on that later.

First things I had to get in order:

Know what is on the bike already

I have 4 Nortons, but only one is a "late" model one, (850 JPS)

So I have stock shocks.

Specs on the OEM Shock

OEM length 329 mm (Just shy of 13 inches.)

Stroke 83 mm

Width 18 mm top and bottom

Spring 22 Nmm Straight rate

Spring free length 224 mm

Installed length (preload) at "0" setting 213 mm

Installed length (preload) at "1" setting 205 mm

Installed length (preload) at "2" setting 198 mm

The Installed height, also known as spring preload, is the length of the spring when it is installed on the shock.

We like to see 15 to 30 mm preload on a twin shock set up.

We have a lot of Harley Davidson experience with twin shocks, some on /5, /6,/7 BMW's and Ducati Bevel drive twins.

With HD's a 1 turn preload increase (1.5mm) equals a 25 lb rider/passenger weight change.

This means if we set up a shock for a 200lb rider, and they add 25 lbs to the bike we increase spring preload by 1,5 mm or on an Ohlins shock 1 turn, 150 lb increase 6 turns, easy, right?

The chart is made on our Shock Dyno using an attachment that allows us to measure springs.

Check what weight that spring may work for by checking Rider sag

With a 209 lb rider:

At "0" preload Static sag 22mm Rider sag 47mm

At "1" preload Static sag 18mm Rider sag 38mm

At "2" preload Static sag 8mm Rider sag 29mm

What we shoot for is the rider sag at 30 mm and the static sag number is a check number, it should be between 5 and 15 mm

We will end up trying 3 different rate springs and see which ones work best for different rider weights.

if we need to try more we can, that part is easy.

18 Nmm, 20 Nmm, and 22 Nmm,

The lighter springs will require more preload assuming the rider weight were to be the same.

This means we could end up using a 18 Nmm spring with a 200 lb rider with a lot of preload, I suspect this is what we will find works best.

Next we ran Dyno tests on the stock shock, and as a comparison on one of the possible Ohlins shocks

I will post these later today, and explain what you are seeing in the charts, as without that they will not mean much.

Back to picking an Ohlins shock to start with.

There are a number of Ohlins shock that are close to that.

Not only does the length have to be correct the stroke, damping, spring rate, width.

We can change anything on the Ohlins shocks, but the closer they are to start with the easier it will be.

There are a few

SU143, Length 331 mm stroke 84mm Out of stock until Oct

DU140 Length 331.5 Stroke 93mm

HD159 Length (adjustable) 324 to 334 mm Stroke 77 mm

I am going to start with this shock, HD159.

This is one of a family of Harley shocks, Ohlins has these in Silver, or Black, with Black springs or Yellow, No chrome.

There are also versions with different part numbers with different features.

Ohlins has 3 versions in 2 colors for the HD's,

The 3 versions are at different price points.

The simplest only has an adjustment for spring preload , no damping or length adjustments (329mm)

The next version has adjustable spring preload, adjustable length, and adjustable rebound damping

The last version has adjustable spring preload, adjustable length, adjustable rebound damping, and adjustable compression damping

More later

Thanks

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