Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > Ohlins Shock Spring Rate Code

[RickyX]

Trying to decipher the spring rate of the spring on my Ohlins shock...
Spring has the following printed on it:

1091-21/75 L461

Doe anybody out there speak Swedish and can translate this into a spring rate (lb/in or N/mm or kg/mm??).

Tak for det (that is Danish but it's not close enough!)

RX

[skidlids]

the 75 equates to 7.5kg/mm

[Edited on 22-11-2004 by skidlids]

[RickyX]

Thanks Kev.

Does anybody know if a 7.5N/MM spring is the correct spring rate for a waif like 10.5 stone rider?
Although I have not had my SPS for long, I get the impression that the rear shock is way too hard.
Also, the bike does not want to turn.
Any advice?

[Harv748]

Well...I'm no suspenders expert, but I'm sure someone with more knowledge and experience will say something along the lines of 'every rider is individual...so is every bike, and every riding style...etc...', so there is no golden rule to follow regarding the 'right' spring.

The 7.4 kg/mm spring is a relatively stiff one, and I think it is the standard spring for a Bip which shows how stiff it is. I have a spring rated around 6.5 or summut. The softer spring gives a nicer ride on the road, but I guess you get more squat when on the gas, equating to perhaps running wide out of the turn blah, blah, blah...

I think a softer spring may help you if you ride on the road...but for the track...perahps its about right?

Pay an expert to set the bike up for you...couple of hundred quid well spent.

[skidlids]

Harv there is a rough rule for spring choice based around loaded and unloaded sag, which will be dependent on riders weight and bike setup, such as length between s/arm pivot and rear axle.
On a standard 748/916 I would say a 7.5kg/mm spring is to hard for a 10 1/2 stone rider. I think you should be looking at a 6.5kg/mm spring and get the rear ride height checked, ideally with a ride height tool if none available Section8 Superbikes have some good info on there website on how to do it from scratch.

[RickyX]

Thanks Guys.......

The issue here is as follows: I had a 748 (Showa F & R) until recently - after 6 years of ownership and much twiddling of the settings I managed to get it to handle like a peach (colloquially speaking).
It was quite softly sprung/damped, ran on the steep head setting, raised rear ride height and with the chain adjusted almost at 9o'clock position (i.e. shortest wheelbase). I liked it like that! I could chuck it into any bends (road or trackday) with a loads of confidence, it turned in great and stopped without excitement. OK so it had the occasional head shake - but hey, that's the bike talking to you isn't it?
Being a fastidious engineer, I had a spreadsheet that detailed all damping settings, ride height (measured with tool) etc etc.
Now I've got the new bike, I've replicated all the settings from the 748 and basically, it feels DANGEROUS!!!
It won't turn in, it feels like the front end is going to slip away, I've got no confidence to crank it over, it has a slight low frequency oscillation through the bars (head bearings too tight?)...
The differences between the bikes are that the SPS has an Ohlins shock/steering damper and the forks have a Maxton mod.
Forks are going back to Maxton to check damping shimming and spring weight so that should sort them.
Now I need to sort the shock. From what has been said, I rekon I need a softer spring...
Rant over.
RX

[keefer]

now I know that race teams run a longer swing arm but I have never seen any of them running the steep head angle
I would put that back to start with, it may of worked on the last bike but I'm surprised

[RickyX]

Keefer,

If it worked on the 748 I don't see why it won't work on the SPS - the geometry etc is the same, just the springs etc that are different.
Oh yeah, I also have the magnesium marchesini's from the 748 swapped over to the SPS, so the unsprung weight effect is the same as before.

[Harv748]

If I read Ricky's reply correct Keefer, he actually has the eccentic hub set so that it gives the shortest wheelbase possible!!!

I used to have my old 748 set with the hub at 3.00 (longest wheelbase possible) and the steering head to fast. I rode it like this for ages, and also set the ride height with the Ducati tool as suggested. Handled sweet and was very stable.

Now I have a 916SP and have the same hub position, same ride height, but now the head setting on normal, as it has mag wheels, I feel this kinda compensates for the steep steering head angle.

I am amazed you where able to ride your 748 on the settings you mention...I'm not suprised it feels dangerous...goes against a lot of whats often said regarding setting up a Duke...but if it works for you (or used to!!)

[keefer]

well that's what I thought harv. It sound so steep I'm surprised the wheels don't touch in the middle.
Well if it works for you good luck.
Not the way I would set up a bike, IMO its best to go a bit at a time