CBR 954 Ohlins shock into Blackbird

[bagofsand]

i am about to sell my 954 Blade and will be removing the Ohlins rear shock, does anyone know if this can be made to fit the Blackbird?

 

[CBRDEAN0]

i am about to sell my 954 Blade and will be removing the Ohlins rear shock, does anyone know if this can be made to fit the Blackbird?

Length will be the first issue.

IIRC the 954 has a 290mm eye to eye shock
The BB has a 320mm eye to eye shock

Also the spring and damping on the 954 shock will be too soft for the BB

 

[slim63]

Also the spring and damping on the 954 shock will be too soft for the BB

How do you come to that conclusion ? You may well be right but I cant see how you got there :dunno:

I agree on the lengths by the way :-0)

 

[bagofsand]

Thanks for the info, so its back to plan A flog this one and buy a Bird specific one

 

[Jaws]

How do you come to that conclusion ? You may well be right but I cant see how you got there :dunno:

I agree on the lengths by the way :-0)

Could be the fact the Bird shock is set up to handle an extra 30-35 kilos weight..

 

[noobie]

yup I think the blade is around 160 ish and the bird around 220 ish kgs, add to that the bird is largely designed for two up and possibly luggage and the blade is primarily designed for one up. So the bird will have a need for a stronger spring

Imagine a fat bird on your balls and then imagine a skinny bird on your balls?

Sorry no reasoning for that last sentence, I was just imagining it :-0)

 

[CBRDEAN0]

How do you come to that conclusion ? You may well be right but I cant see how you got there :dunno:

I agree on the lengths by the way :-0)

The 954 has a 14.6kg/mm rear spring from the factory

The BB has a 16.8kg/mm rear spring from the factory


That puts the 954 spring around 15% softer than the BB and the BB is generally under sprung anyhow.

Damping is there to control the spring so it would make sense that the damping is probably 15% lower as well.

 

[mikeyw64]

Thanks for the info, so its back to plan A flog this one and buy a Bird specific one

Or sell it with the blade

 

[slim63]

The 954 has a 14.6kg/mm rear spring from the factory

The BB has a 16.8kg/mm rear spring from the factory


That puts the 954 spring around 15% softer than the BB and the BB is generally under sprung anyhow.

Damping is there to control the spring so it would make sense that the damping is probably 15% lower as well.

Which means exactly nothing as its a different set up with different rising rate & different length swingarms acting on them :-0) as usual people forget leverage & the fact that a full on sports bike is liable to be set up stiffer as stock than a lardy sports tourer

Still you are probably correct in your assumption but to state its going to be soft without doing the maths fully is misleading imo, no doubt jaws will be along to give us ratio's etc soon :-0)

 

[slim63]

just to add to that my stock shock on my bird is completely knackered& as soft & soggy as you can get as anyone who has ridden it will tell you but its still way to stiff for me riding solo :whi5tl:

 

[CBRDEAN0]

Which means exactly nothing as its a different set up with different rising rate & different length swingarms acting on them :-0) as usual people forget leverage & the fact that a full on sports bike is liable to be set up stiffer as stock than a lardy sports tourer

Still you are probably correct in your assumption but to state its going to be soft without doing the maths fully is misleading imo, no doubt jaws will be along to give us ratio's etc soon :-0)

Not all assumption.

Based on various spring rate calculators - a 14.6kg/mm spring on the rear of a blackbird is good for a 51kg ( 8 stone ) rider

Where as a 14.6kg/mm spring on the rear of a 954 is good for a 75kg ( 12 stone ish ) rider

If the 14.6kg/mm spring was correct for the OP on a 954 and assuming he hasn't lost 24kg overnight - it would be too soft for him on a BB.

 

[slim63]

Not all assumption.

Based on various spring rate calculators - a 14.6kg/mm spring on the rear of a blackbird is good for a 51kg ( 8 stone ) rider

Where as a 14.6kg/mm spring on the rear of a 954 is good for a 75kg ( 12 stone ish ) rider

If the 14.6kg/mm spring was correct for the OP on a 954 and assuming he hasn't lost 24kg overnight - it would be too soft for him on a BB.

Still missing the point mate :whi5tl: research rising rate suspension, then think about what you just wrote :-0)

 

[CBRDEAN0]

Still missing the point mate :whi5tl: research rising rate suspension, then think about what you just wrote :-0)

Then I guess everyone else out there recommending spring rates has it completely wrong too.

Never mind - I will stick to what I know works.

 

[slim63]

Then I guess everyone else out there recommending spring rates has it completely wrong too.

Never mind - I will stick to what I know works.

Nobody said you were wrong, the point you seem to be missing is that your opinion is based purely on spring rates when that is not the only factor at work here

Sure if swapping different rated springs on the same bike your theory holds up but not always if swapping a spring/shock from one model bike to another

Simple enough ? :-0)

 

[CBRDEAN0]

Nobody said you were wrong, the point you seem to be missing is that your opinion is based purely on spring rates when that is not the only factor at work here

Sure if swapping different rated springs on the same bike your theory holds up but not always if swapping a spring/shock from one model bike to another

Simple enough ? :-0)

Not just based on spring rate
The 954 and the BB both have a 3:1 axle to shock ratio.

Agreed the BB probably has a steeper rising rate than the 954 but using such a soft spring will have the bike sitting quite a bit further down at the rear compared to the correct spring.

 

[slim63]

Not just based on spring rate
The 954 and the BB both have a 3:1 axle to shock ratio.

Agreed the BB probably has a steeper rising rate than the 954 but using such a soft spring will have the bike sitting quite a bit further down at the rear compared to the correct spring.

Make your mind up either its a 3:1 ratio or its rising rate ? :-0)

A spring could only be called soft if the load applied to it was too great (which it may be in this case)

But load isn't all about weight once mechanical force is applied IE levers or linkages so it is perfectly possible (although unlikely in this case) for a "soft" spring carrying more weight to compress less ... less mechanical advantage

just to be awkward you could also have falling rate suspension or linear if you wanted :whi5tl:

And another point from your post above if a fireblade was set up as stock to carry the weight of the bike plus X amount of rider & that alone as you seem to suggest what do you think would happen when adding X amount of pillion? a soggy unrideable mess? that simply does not happen

Now we have killed that subject & are never going to agree shall we talk damping 8rfl@

 

[Jaws]

And another point from your post above if a fireblade was set up as stock to carry the weight of the bike plus X amount of rider & that alone as you seem to suggest what do you think would happen when adding X amount of pillion? a soggy unrideable mess? that simply does not happen

True and true as even the bird is compromised when a pillion is added.