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 Good shock for my GRiSO??

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klaas123
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PostSubject: Re: Good shock for my GRiSO??   Tue Aug 22, 2017 5:46 pm

We will find out, can always return to the shitty Sachs and sell the Ohlins Smile
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Brent S
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PostSubject: Re: Good shock for my GRiSO??   Tue Aug 22, 2017 5:58 pm

klaas123 wrote:
I know 95N/mm is on the low side for my weight but it was cheap and in stock so will give it a try.

Just out of interest, my Wilbers rear shock came with a 95N spring. I'm 75kgs myself (closer to 85kgs in battle gear). It sat a touch low to begin with, so adjusted via a couple of turns more pre-load and it seems to be pretty good now. Compliant and well controlled. That said, my gut feel is that the 95N is still at the low end of the range, and I'd be nervous recommending a 95N to anybody even slightly heavier than I am. If I had my time again, I would have liked to try a 105N. It may well have been a bit firm, but at least I would have known.


Last edited by Brent S on Wed Aug 23, 2017 7:40 am; edited 1 time in total
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klaas123
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PostSubject: Re: Good shock for my GRiSO??   Wed Aug 23, 2017 6:56 am

Just thinking, we could make a spacer behind the rubber stop to equal the travel of the shock to the Sachs if needed.
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Nobleswood
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PostSubject: Re: Good shock for my GRiSO??   Wed Aug 23, 2017 5:52 pm

What is the travel on the Sachs for the GRiSO & the Stelvio ?

On the Ohlins that Waterbottle fitted to his bike what was the shock travel on it ?
He has already been down this road.

I'll get those measurements after supper, Sidrat
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ghezzi
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PostSubject: Re: Good shock for my GRiSO??   Wed Aug 23, 2017 6:17 pm

Well at least you guys are thinking hard on solutions ....................

The unquantifiable part (beyond my abilities) is;
Within the shocks internals, are bleed ports/holes etc that are at specific points, to correspond with a point in the range of wheel travel. ie. Like around the rider sag point.

Damping is the secret to compliance, comfort and handling. Spring is just to keep ya balls outta the bindi's.

If you limit a shocks travel, to say 50%, then important aspects to the progressive damping action may never come into play.

Just sayin ..................... Suck it and see.
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Nobleswood
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PostSubject: Re: Good shock for my GRiSO??   Wed Aug 23, 2017 6:27 pm

Good point.

As we are taking a unit, a shock & just trying to see if the numbers are close enough for us to work with.

So to refresh; the overall length is apparently slightly longer. Which makes it closer to the Stelvio shock.

The shock travel is thought to be longer as well, but waiting on some figures for the GRiSO & Stelvio units to confirm that.

Waterbottle, with your help, got one onto his racing machine, so figures from that shock would help us know what we are getting into.

That's my understanding of where we are currently.
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Brent S
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PostSubject: Re: Good shock for my GRiSO??   Wed Aug 23, 2017 8:40 pm

Interesting point Ghezzi. Just because a shock will "fit" between the upper & lower fixing points, does that imply it will work properly? If we look at cars for example, take a humble C-Class Mercedes base model. Then take the balls-out AMG version. My understanding is that the shock point architecture is essentially identical, yet an AMG shock will behave totally differently to the garden variety model, the reason being almost entirely due to different valving.

So, without wanting to draw too long a bow here, would the Stelvio potentially have valving that is more suited to secondary roads and touring with luggage, as opposed to a more street-oriented machine like the GRiSO? No doubt somebody somewhere has pulled a GRiSO and Stelvio shock apart and looked at the valving, but I haven't really read anything much about this. Granted, the valving on the stock GRiSO Sachs unit is rubbish anyway, so you'd be hard pressed to find anything that made it worse. Just a thought anyway.
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Nobleswood
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PostSubject: Re: Good shock for my GRiSO??   Wed Aug 23, 2017 8:58 pm

[quote="Brent S"]Interesting point Ghezzi. Just because a shock will "fit" between the upper & lower fixing points, does that imply it will work properly? If we look at cars for example, take a humble C-Class Mercedes base model. Then take the balls-out AMG version. My understanding is that the shock point architecture is essentially identical, yet an AMG shock will behave totally differently to the garden variety model, the reason being almost entirely due to different valving.

Exactly !
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ghezzi
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PostSubject: Re: Good shock for my GRiSO??   Wed Aug 23, 2017 10:45 pm

My experience is with the Bellagio.

Swingarm, 'L' shaped rocker and link rod part numbers are identical for Bellagio, GRiSO and I think Stelvio (I haven't checked all CARC models).

Do Breva, Sport and Norge all share the same frame? Bellagio and GRiSO have different frames and I assume Stelvio does to. That makes 4 different frame designs, with different geometry.

Even if all 6 models used identical swingarm and linkages etc, what I cannot compare,
is the location of the link rod pivot point on the frame under the swingarm, and the location of the top shock mount.

Talking Bellagio/GRiSO/Stelvio with shock length of 'x' mm.
These two frame mounting points will not only affect ride height, but also the orientation of the 'L' shaped rocker, which in turn affects the ratio and its rate of rise.

I do know Bellagio shock is approx 310mm with a stroke of 55mm (without bump stop rubber).
GRiSO shock is longer, approx 320mm but with a shorter stroke of 50mm (w/o bsr) I just measured them.
Stelvio shock is longer again ......................
Ron squashed a 24mm bump stop rubber down to about 6mm.

I also know the Bellagio had less than 100mm rear wheel travel and a rocker ratio that started from a lot less than 3:1.

Three bikes, a cruiser, a sporting model and an adventure tourer, three different shocks, three different lengths, three different springs, and damping and ..................
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Pete Roper
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PostSubject: Re: Good shock for my GRiSO??   Wed Aug 23, 2017 11:19 pm

All the CARC bikes use the same swingarms, linkage etc. The differences are in the frames There are basically three frame types. Stelvio, Bellagio and GRiSO are stand alone. Breva, Sport and Norge all share the same frame. That being the case there is obviously enough available 'Angle' in the reactive shaft system to allow longer travel than the models with shorter shocks, (Breva/Sport/Norge, Bellagio and GRiSO.) but where and how this is accommodated in the frame design of the Stelvio I don't know.

Pete
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klaas123
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PostSubject: Re: Good shock for my GRiSO??   Wed Aug 23, 2017 11:22 pm

All good points (as always) Ghezzi. I hope Ron (Waterbottle) will find time to chime in, he has experience with a Ohlins shock on his track bike.
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klaas123
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PostSubject: Re: Good shock for my GRiSO??   Thu Aug 24, 2017 4:59 am

Pete Roper wrote:
That being the case there is obviously enough available 'Angle' in the reactive shaft system to allow longer travel than the models with shorter shocks, (Breva/Sport/Norge, Bellagio and GRiSO.)

Pete

Good news for us, thanks Pete
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sidrat
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PostSubject: Re: Good shock for my GRiSO??   Thu Aug 24, 2017 6:50 am

Pete Roper wrote:
All the CARC bikes use the same swingarms, linkage etc. The differences are in the frames There are basically three frame types. Stelvio, Bellagio and GRiSO are stand alone. Breva, Sport and Norge all share the same frame. That being the case there is obviously enough available 'Angle' in the reactive shaft system to allow longer travel than the models with shorter shocks, (Breva/Sport/Norge, Bellagio and GRiSO.) but where and how this is accommodated in the frame design of the Stelvio I don't know.

Pete

That is my only question, and if you don't know the answer..........
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Pete Roper
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PostSubject: Re: Good shock for my GRiSO??   Thu Aug 24, 2017 7:58 am

It's because I've never had need to check before.

As soon as I get a chance, (Which will be after we've slotted the 1400 into Mark's GRiSO and after i's stuck my new Sachs and Matris front end into mine AND had my Matris rear shock re-sprung and valved by Mr. L. Smith in Fyshwick!) I'll take the Turd off the road and do some measuring but really it's a bit of a furphy I'd think.

The factory will always take the cheapest route. Go through the possibilities in terms of potential useage and geometry and I think you will find that as far as both geometry and construction constraints as long as the published travel abilities of the system aren't exceeded by more than 10% it will all be golden BUT I'm not willing to put my reputation on that observation so don't try the 'Well! Roper Said!' Card

Pete
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ghezzi
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PostSubject: Re: Good shock for my GRiSO??   Thu Aug 24, 2017 3:55 pm

so don't try the 'Well! Roper Said!' Card

Ditto!

My disclaimer is, I've got a Bellagio, GRiSO is different.
I also have Tony Foale's Suspension Kinematics program that helps me to understand geometry changes. ................ but I ain't got a GRiSO to measure and check.
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sidrat
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PostSubject: Re: Good shock for my GRiSO??   Thu Aug 24, 2017 4:26 pm

Ghezzi hapy to measure min so you an put it throught tony foales software, now he really does know about suspension!
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Nobleswood
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PostSubject: Re: Good shock for my GRiSO??   Thu Aug 24, 2017 9:01 pm

Just found this in a thread 'Ohlins rear spring rates' authored by Waterbottle' ;

Built this today........

And at ghezzi's request did some measuring.....
Original Sachs Shock :
Stroke = 41 mm - Compressing the bump stop hard to about 5mm thick
Free length of spring = 188 mm. (Yes 188mm) Coil Dia-11.3 mm. ID-56mm OD-79 colour RED

Ohlins AP9340 Shock :
Stroke = 52mm - compressing bump stop to about 11mm thick, quite hard with this much force.'

I take from this that Waterbottle measured the stroke as 52mm + 11mm for the bump stop = 63mm

Which is the same as the stroke I'm reading from my spec sheet for the AP8271 shock. Which is measured from the body to where the bump stop sits.

That's my current therory anyway.

Klaas, Baross found a clevis mount from Forsaken Motorsports in Canada for $100 Canadian. Let me know what you got from Ohlins.
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ghezzi
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PostSubject: Re: Good shock for my GRiSO??   Thu Aug 24, 2017 9:44 pm

Nob-les-wood jocolor

I am pretty sure the 52mm was the Ohlin shock compressed to the max (min) with bump stop rubber in place and squashed as much as he could in the vice.

Although, with the main spring removed, eye-to-eye starting point may have been reduced if it had an internal "top out" spring. (so many intricate variables in which to miscalculate)

Sachs rubber is quite soft and my original has split and disintegrated.
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Nobleswood
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PostSubject: Re: Good shock for my GRiSO??   Thu Aug 24, 2017 9:48 pm

So this was an actual ,' compress the shock & see what it measures' measurement not just guesstimate.
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ghezzi
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PostSubject: Re: Good shock for my GRiSO??   Thu Aug 24, 2017 10:26 pm

Yep.
Ron - Original Sachs Shock :
Stroke = 41 mm -Compressing the bump stop hard to about 5mm thick


The measurements I did were on a fully assembled GRiSO Sachs (guestimate with verniers and dirt in me eye)

The only way to be certain of all measurements of travel etc is;
1. Measure the Ohlins length while fully assembled.
2. Remove spring and measure again. (checking for internal top out spring)
3. Install shock on bike with out spring.
4. Let it hang fully extended. (against internal top out spring) = full ride height.
5. Using dial gauges and hydraulic jack etc, compress shock (upwards) in 1mm increments, while recording actual (axle) rear wheel travel.

Not only will you have total shock and wheel travel, but the rocker ratio graph with its start/finish/av numbers, plus any wheel/swingarm clearance issues.
The figures I have only relate to the Bellagio.

If you did this with the Sachs first, you will get a comparison set of numbers to show how things have changed with a longer shock.
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Baross
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PostSubject: Re: Good shock for my GRiSO??   Fri Aug 25, 2017 1:20 am

Just to confirm - my shock is an Ohlins AP8271. With the Forsaken Motorsports clevis fitted and ride height adjuster fully wound in, plus about 20% preload, the eye to eye length was about 335 mm or about 20 mm longer than the Sachs. An Ohlins clevis may be a touch shorter. I couldn't be happier with the outcome.
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sidrat
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PostSubject: Re: Good shock for my GRiSO??   Fri Aug 25, 2017 9:06 am

Hey baross sounds like you have made a choice that suits you. How much did the seat height increase with the new shock? And did you make any changes to the front end?
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klaas123
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PostSubject: Re: Good shock for my GRiSO??   Fri Aug 25, 2017 11:01 am

Received the ordered parts from the Dutch Ohlins importer today, both parts are brand new and costed 95 euro together! Very Happy

Nobleswood, there is no inscribtion number or name on the 25mm clevis unfortunatly Sad

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Nobleswood
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PostSubject: Re: Good shock for my GRiSO??   Fri Aug 25, 2017 11:05 am

That's a good price !

Cheap as chips !

Bugger about no part number.
Could you give me the link to the seller
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klaas123
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PostSubject: Re: Good shock for my GRiSO??   Fri Aug 25, 2017 11:16 am

Next week I will collect the shock during a small trip on the GRiSO.

This is the adress of the seller, you can mention my name, Klaas Bloem [You must be registered and logged in to see this link.]

Sellers name is Wim Kroon, [You must be registered and logged in to see this link.]

Have to say I got this spring very cheap, the heavier spring that was not in stock would have cost me more.
Good reason to lose some weight Smile Smile


Last edited by klaas123 on Fri Aug 25, 2017 11:45 am; edited 3 times in total
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