My '04 M1000 S is getting an Ohlins S46PR1C1S shock. I weigh 145 without gear. What spring do I need?
Call Eric... :P
Doh! Good idea! Don't want to bother him so I will send him an email.
Thanks!
Quote from: howie on January 13, 2015, 05:15:09 AM
Doh! Good idea! Don't want to bother him so I will send him an email.
Thanks!
He lives on the phone. ;)
Just call after 9 when he gets to the shop. He can probably supply it too.
Can't hurt to ask.
Quote from: howie on January 13, 2015, 05:06:28 AM
My '04 M1000 S is getting an Ohlins S46PR1C1S shock. I weigh 145 without gear. What spring do I need?
I weight slightly less, ride mostly 1-up, and use a 95N/mm spring on one bike, and 100N/mm on the other (Monster 900-02 and 800-03; same frame as you have).
I've tried an 85N/mm once, definitely too soft. 100N/mm would be my recommendation.
Thanks. I should have mentioned mostly shitty condition New York street riding. Same recommendation?
My recommendation for the spring? Update your spell check function. ;)
Meanwhile, in other news, I need to arrange a meet up to get that helmet case from you. Trip is 2.5 weeks away...
Quote from: howie on January 13, 2015, 09:33:43 AM
Thanks. I should have mentioned mostly shitty condition New York street riding. Same recommendation?
Well, for me I'd stick with the springs I have, but in the end only testing will tell. I suppose a well-established suspension shop could swap the spring for you for a reasonable fee, should you not be happy with the first shot. For street riding I personally prefer slightly softer springs with slightly more pre-load, but too soft does of course does not work at all.
Quote from: 1.21GW on January 13, 2015, 09:59:34 AM
My recommendation for the spring? Update your spell check function. ;)
Meanwhile, in other news, I need to arrange a meet up to get that helmet case from you. Trip is 2.5 weeks away...
Got it correct once, wrong once. Batting 500, that ain't bad :P
Didn't know you wanted the bag. You could have had it Friday, we were in Brooklyn. Wanna make a trip up to the Bronx?
Quote from: MonsterHPD on January 13, 2015, 10:25:47 AM
Well, for me I'd stick with the springs I have, but in the end only testing will tell. I suppose a well-established suspension shop could swap the spring for you for a reasonable fee, should you not be happy with the first shot. For street riding I personally prefer slightly softer springs with slightly more pre-load, but too soft does of course does not work at all.
Thank you. Just what I was looking for.
Quote from: MonsterHPD on January 13, 2015, 10:25:47 AM
Well, for me I'd stick with the springs I have, but in the end only testing will tell. I suppose a well-established suspension shop could swap the spring for you for a reasonable fee, should you not be happy with the first shot. For street riding I personally prefer slightly softer springs with slightly more pre-load, but too soft does of course does not work at all.
I prefer a slightly stiffer spring with less pre-load...go figure.
My experience is the more preload on a spring the harsher the ride, particularly on the kinds of roads we have in the northeast.
I'd go along with the 100 N/mm spring recommendation for you, Howie.
I'd ask Eric about taking out some compression damping prior to putting the shock on the bike.
IMO:
The Ohlins seem to be set up with the firm damping/soft spring philosophy.
Good for racetrack, but not so compliant on sharp-edge bumps in the real world.
Both of my Ohlins-equipped bikes ('02 S4 and '98 M750) I've got the compression damping adjust at full soft, or as soft as I can go without it getting wallowy.
The compression damping adjust is primarily effective at low shaft speed, so 'fixing' a high-speed damping issue with it is a compromise.
Both shocks will get shims removed from the compression stacks the next time they're serviced.
Quote from: ducpainter on January 13, 2015, 10:44:43 AM
I prefer a slightly stiffer spring with less pre-load...go figure.
My experience is the more preload on a spring the harsher the ride, particularly on the kinds of roads we have in the northeast.
I suppose we're talking nuances here. If the softer and stiffer springs are pre-loaded to give the same initial force, the softer spring will require less force for the same wheel travel than the stiffer, which, on the other hand, will provide more reserve. .
However, as noted above, too soft is absoutely bad, and too soft a spring might allow the travel to reach massively into the bump rubber, I suppose that would give a harsh suspension action on big bumps.
Quote from: Speeddog on January 13, 2015, 11:34:19 AM
Both shocks will get shims removed from the compression stacks the next time they're serviced.
I did that to my M900 shock last year, and have just done so for the M800 now. Big improvement!
Quote from: MonsterHPD on January 13, 2015, 11:37:33 AM
I suppose we're talking nuances here. If the softer and stiffer springs are pre-loaded to give the same initial force, the softer spring will require less force for the same wheel travel than the stiffer, which, on the other hand, will provide more reserve. .
However, as noted above, too soft is absoutely bad, and too soft a spring might allow the travel to reach massively into the bump rubber, I suppose that would give a harsh suspension action on big bumps.
Agreed, except the preload required to maintain correct sag on a softer spring, and the force to initiate movement might very well exceed the force to get the stiffer spring moving at the preload required to maintain sag. Once moving the rate is the rate.
My old DU-440 seems to damp fine with a stiffer spring Nick.
Quote from: ducpainter on January 13, 2015, 12:24:53 PM
Agreed, except the preload required to maintain correct sag on a softer spring, and the force to initiate movement might very well exceed the force to get the stiffer spring moving at the preload required to maintain sag. Once moving the rate is the rate.
My old DU-440 seems to damp fine with a stiffer spring Nick.
Well,
may be a case of bad thinking on my part, but anyway: since the suspension is not topped out, the bike will sit on the force provided by total spring compression ((pre-load + sag) x spring rate). Everything else beeing the same, I'd assume that a given amount of sag will be the result of a given spring force, regardless of spring rate nd amount of pre-load, as long as the sum is the same.
But in the end, testing and personal taste decides the issue.
In a force-vs. spring compression diagram, the springs will be represented by straight lines of different inclination; I'd assume that the lines will cross at the point of same sag, of course provided the same sag has been set?
If the suspension was topped out, like I think it is on small-displacement road racing bikes, the situation is different.
EDIT:
As is usually the case in mechanical matters, nothing is black or white.
Returning the spring diagram, with 2 different springs set to the same sag, the softer spring will have the flatter, less inclined line. This means, that at spring compression numbers less that that corresponding to the set sag, the softer spring with more pre-load
will actually be stiffer.
I'm not sure how that will feel; one might think that wheel travel less that the static sag will not matter much, but maybe it does ...?
The shock is from ECS, in stock, I fell to temptation. Steve will give me any spring I want, same price. As far as valving goes, yeah I agree with the stacks, but it will stay stock 'till the first service. I'll go either with the 95 or 100 and leave it up to Steve.
Thanks all!
Quote from: MonsterHPD on January 13, 2015, 01:01:10 PM
<snip>
EDIT:
As is usually the case in mechanical matters, nothing is black or white.
Returning the spring diagram, with 2 different springs set to the same sag, the softer spring will have the flatter, less inclined line. This means, that at spring compression numbers less that that corresponding to the set sag, the softer spring with more pre-load will actually be stiffer.
I'm not sure how that will feel; one might think that wheel travel less that the static sag will not matter much, but maybe it does ...?
It feels...
stiffer. ;D
Actually to my ass it feels harsher.
Quote from: howie on January 13, 2015, 01:42:51 PM
The shock is from ECS, in stock, I fell to temptation. Steve will give me any spring I want, same price. As far as valving goes, yeah I agree with the stacks, but it will stay stock 'till the first service. I'll go either with the 95 or 100 and leave it up to Steve.
Thanks all!
He'll treat you right. He's a good guy.
Going with the 95. By the way, Nate is correct and it might show up on the NH washboard roads. The theory ain't that hard. Application is with my limited riding skills. Both Steve and Eric say 95 for me. Can't go wrong.
Again, thank you all.
Quote from: ducpainter on January 13, 2015, 02:03:32 PM
It feels...
stiffer. ;D
Actually to my ass it feels harsher.
I figured this issue deserved a little bit of analysis, and as always there's more than immediately meets the eye....
Using fork springs as an example, I checked for 8.5N/mm and 10 N/mm. Assuming 0 preload for the 10N-spring, and 20 mm for the 8.5N-spring, the 10N-spring will actually be softer all the way to approx. 110 mm travel.
I've not checked where this might lead transferred to the rear, with all the very progressive linkage and all, but sag numbers will give an indication: If the empty sag is small, and the loaded sag is high, the spring is too soft.
The rest is down to personal taste ....
Quote from: MonsterHPD on January 15, 2015, 01:23:56 PM
I figured this issue deserved a little bit of analysis, and as always there's more than immediately meets the eye....
Using fork springs as an example, I checked for 8.5N/mm and 10 N/mm. Assuming 0 preload for the 10N-spring, and 20 mm for the 8.5N-spring, the 10N-spring will actually be softer all the way to approx. 110 mm travel.
I've not checked where this might lead transferred to the rear, with all the very progressive linkage and all, but sag numbers will give an indication: If the empty sag is small, and the loaded sag is high, the spring is too soft.
The rest is down to personal taste ....
My take on the subject...
it's voodoo.
I can say that a soft rear spring preloaded to give a 'somewhat near' sag number will feel much harsher/stiffer than a heavier spring with very little preload. If that fits into the equation then fine. If not, it still doesn't change the 'feel'.
I've played with fork oil and springs, but anything more than that, I give to the suspension guy. There's too much to learn as it is. ;)