Which shock absorbers?

gortnipper · Apr 30, 2020

I am not sure I would buy a Nitron. It just happened to come with the bike, and I have ridden other same model stock bikes to know the difference.

I did have to work the settings quite a bit to get it right from the PO's weird ones.

kommando · Apr 30, 2020

To avoid polluting the thread, even if it has already gone off the rails anyway, I have started a thread on varying compression rates in 76 series Koni's and by inference also 7610's.

https://www.accessnorton.com/NortonCommando/adjusting-compression-damping-rate-in-koni-shocks.30349/

jseng1 · May 3, 2020

According to the charts the IKONs for Norton only have 2" of travel. The Hagon type shock has 2-1/2" travel. I'm shopping but having trouble finding enough travel.

jseng1 · May 4, 2020

This is what I'm talking about. The Hagon shock has over 2-1/2" travel. The Ikons for Nortons have only 2.1" I'm not willing to give up travel and increase bottoming.

I don't like the Hagons on my lightweight featherbed because they have too much compression damping. But they've lasted over 30 years.

gortnipper · May 4, 2020

I just measured my 7610s and they are a shade over 67mm, which is 2.6".

Fast Eddie · May 4, 2020

In my experience of shocks, quality of damping, and good control of high / low speed damping as mentioned by Kommando, is far more relevant / important that an extra half inch of travel.

A well damped shock just won’t need as much travel as a bad ‘un.

And a bad shock with more travel is still a bad shock !

kommando · May 5, 2020

On the dedicated Norton Commando Koni shocks the travel is limited by a 25mm solid spacer under the bump rubber. The same shock without the spacer is used on the T120, this was Koni's way of using the same body for many applications. You can take the spacer out but in the Commando the tyre will start to rub the underside of the mudguard. Ikon may have revised the body for Commandos, as per Gorgrippers, restoring the full movement but not changed the data sheet or it's an old data sheet.

gortnipper · May 5, 2020

kommando said:
On the dedicated Norton Commando Koni shocks the travel is limited by a 25mm solid spacer under the bump rubber. The same shock without the spacer is used on the T120, this was Koni's way of using the same body for many applications. You can take the spacer out but in the Commando the tyre will start to rub the underside of the mudguard. Ikon may have revised the body for Commandos, as per Gorgrippers, restoring the full movement but not changed the data sheet or it's an old data sheet.

2.6" measurement is outside of the bump spacer, so if I took that off it would be 3.6".

gortnipper · May 5, 2020

gortnipper said:
2.6" measurement is outside of the bump spacer, so if I took that off it would be 3.6".

Why would they limit it.

ludwig · May 5, 2020

gortnipper said:
Why would they limit it.

Maybe because the inclined position of the dampers on a Commando translates to more wheel travel than if the shock was more vertical, like on an Atlas.

kommando · May 5, 2020

This is a 76 series Koni from the 80's showing how Koni limited the movement for their Commando shock.

Total movement 4.5", 25mm spacer and 25mm bump stop reduce this to 2.6"

This is the arrangement Ikon would have inherited but hopefully they have now limited the travel internally within the body as the spacer splits in half and can then actually create a 50mm spacer. Gorgrippers measurements confirm this is the way they have gone.

maylar · May 5, 2020

Fast Eddie said:
A well damped shock just won’t need as much travel as a bad ‘un.

The spring preload also plays a part in this. If I was bottoming out the shocks in bumps I'd click the springs up by a notch. This is also where having progressive springs helps, so normal roads don't give you a harsh ride.

jseng1 · May 5, 2020

Unfortunately Ikon doesn't have an up to date chart showing overall shock lengths and travel. They have a chart here:

https://www.ikonsuspension.com/shock-absorber-details/

But many options are missing (the length and travel specs). The 76-3000 series (76-3044 for Commando and 76-3006 for Atlas) aren't even listed.

Brooking 850 · May 5, 2020

Off their site

jseng1 · May 5, 2020

Brooking 850 said:
Off their site
View attachment 16046

What I meant was that the length and travel specs aren't listed for the 76-3044 (for Commando) and 76-3006 (for Atlas) Makes it difficult to work out detials.

Frankie17 · May 7, 2020

you also have to factor piston rod to body ratio the longer the shock body = more travel as piston rod can also be made longer

most 12.9" road shocks have a body long enough to allow 3" of piston rod travel shorter units say 12.4" normally have 2.5" travel using a longer piston rod would require a longer body which increases shock length
so i think it is wishful thinking to find a 12.9" Commando shock with longer travel , this will vary slightly depending on manufacturer but only by a nominal amount , on stock road shocks spring rate is a trade off the spring controls the rate of compression and the damper works against it on return bear in mind rider weight will vary dramatically , so stock shocks are made to cover a broad church so to speak
high end shocks with compression and re bound adjustments still have the same restrictions of piston rod travel vs shock length , but compression can be slowed using the compression damping adjustment
spring rates can also be changed to match your own weight requirements and avoid bottoming out

jseng1 · May 7, 2020

For example the Hagon's compress to 10" with 2.5"+ travel. The compressed length is important because it prevents your tire from rubbing the fender. But if you can find a shock with more extension with the same 10" compressed distance - you have more suspension to work with.

Here's an interesting shock - the Ikon 76-1290 measures 12.4" length with 4.2" travel. This one breaks the rules.

Frankie17 · May 7, 2020

jseng that Ikon 76-1290 is not a shock It is a cartridge insert for BMW earls forks No spring platform and threaded body has additional length as it has no mounting eye
so you are not comparing like for like fitting a bottom mounting eye reduces working length by around 1.5" so this body has the working range equal to a 14" conventional shock hence 4.2" rod travel

jseng1 · May 7, 2020

Frankie17 said:
jseng that Ikon 76-1290 is not a shock It is a cartridge insert for BMW earls forks No spring platform and threaded body has additional length as it has no mounting eye
so you are not comparing like for like fitting a bottom mounting eye reduces working length by around 1.5" so this body has the working range equal to a 14" conventional shock hence 4.2" rod travel

I was wondering why it had so much travel.

So I'm looking for a rebuildable shock with 10" compressed length and 3" travel. I'd be happy with an Ikon 76 series that fit but they all list short travel (approx 2.1")

The Ikon 76-1373 is close but only 2.2" travel

Craig · May 7, 2020

Been a very educational thread for sure , thanks from me ! .... in original post “ landspeed”mentioned he prolly would never notice the difference in whatever he put on rear end .... he sure did get a lot of info , not sure this overload helped him as much as it did me , though I suspect as irrelevant for him as it is to my ride style ..... still very interesting reading and still surprising how much knowledge found on this forum , even after all this time ....

Which shock absorbers?

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