Let the fun begin...RPM Rear Shock

[ribbert]

Mike,

What you describe at length is simply what any good suspension should do and my expectation is the RPM shocker should be better because it is tailored to the FJ. I have said previously I will be elbowing my way to the head of the queue when they are released.

It was no slight on Randy's unit, but, you said it yourself, the full length of travel on both the forks & shock were in play. I simply commented that with the shocker compressed by either centrifugal force, brakes or bumps, the bike will be closer to the road and that effects clearance.

The more irregularities the wheel soaks up without the bike rising and falling, the more the clearance is going to change. This is a good thing for general riding. But, if you are leaned over in a corner and hit a bump and this is absorbed entirely into the suspension you are more likely to ground out.

Yes the shocker can no doubt be set to suit sportier riding as it could be for high speed, pillion or comfort but the fact is most people don't because a ride can involve all of that and most of us can't be bothered and settle on a good all round setting and leave it there.

I look forward to the improved ride I expect from the RPM unit but still maintain that in my case (on my current settings) it will be at the expense of some clearance, a compromise I am happy to make in order to get a better all round ride. If you have your bike currently set to mushy this will not be the case.

I am not easily swayed by individual claims as to a particular product's performance/ Empirical experience is not easily compromised.
[/u]
I agree, and to be fair, your findings are only relative to the previous set up on your bike and will be different to mine which will be different to someone else's and so on.

Just so I'm not misquoted, again (think gun section)

My comment would apply to any shocker that allowed good performance with softer springs and has NOTHING to do with Randy's item specifically and I think the RPM unit will be the best thing you can do for your rear end.

BTW, I regularly ride a modern 1200 with 3 mode electronic suspension adjustment. This is way more than bling and makes a huge difference being able to adjust it on the fly as conditions demand. Randy?

Noel

[Mike Ramos]

Good morning,

Well, reread the post I made dated May 18th (which was in an email I sent originally to Randy right after the ride ended).  It closes with the following:

"I cannot emphasize the performance of your suspension and anyone who says there is anything better for street use is foolish.  Penske shock or USD forks just cannot compete nor compensate for all the differences in road conditions; it is impossible to set either to optimum settings outside of a track setting.   

I will even state that your suspension is "active" which is attained without electronics.  I have ridden the gamut of types of road surfaces [with your suspension over these 9,000 plus miles] and road conditions and every reaction of the suspension has been instantaneous.  I cannot fathom how a rider is supposed to toggle from "sport" to "highway" to ''[take your choice of vernacular]'' when street riding changes literally from moment to moment."

There would not have been time to change between settings as the road conditions were changing so quickly.  Go wind your bike up to near red line in 4th with the tallest gearing available to determine what speeds were encountered, I do not know as I was busy riding. As it was not in a track setting there were a myriad of other factors to consider at the moment.

Also refer to a previous posting of a video where with the camera pointed backwards there is an exit in a right hand sweeper that is very rough.  The wheel is very active and the road is initially smooth and then the rough surfaced turn is entered.  Returning to smooth again.   It may be the same posting where I caught up to a late model Yamaha sport bike on an open road and the road is smooth.

The changes in road conditions are instantaneous but the suspension compensates very nicely.

I have noted my findings & experience and expressed them as well as I am able.  That is about all I  can say.

Have a good day,

Mike Ramos.

[racerrad8]

So, before we get to far off topic, I want to reaffirm the question asked regarding raising the rear ride height.

The primary reason seems to be to reduce the rack/caster to allow quicker lighter steering.

The secondary reason should be due to later model wheel/tire combination with a shorter static height reducing the ground clearance.

Is there any other reason for a shock with height adjustment?

Randy - RPM

[FJmonkey]

Being the one that kicked the hornets nest I can say that sums up why I was interested in the adjustment. It is not an adjustment I would be changing all the time, I want to find the sweet spot and leave it.

[racerrad8]

Raising the back or lowering the front is obviously the easiest and cheapest solution. An adjutable lenght shock allows you to change the ride height and thus change the trail. It does not affect  spring sag or preload nor will it affect damping.

Changing the links will also do this but an adjustable length shock will allow for more tuning without making up an assortment of links to play with.
Hein.

Hein,

Thank you for the reply, but after doing all of the testing I have done and conversed with the manufacture, the above statement is incorrect.

The changing of the fulcrum points due to a longer shock drastically affect the dampening and slightly affect the sag & preload. The leverage change of the fulcrum points regarding the swing arm linkage by changing the shock length has a lot of considerations.

When the shock length changes the angle correction factor must be taken into consideration. Not only does it modify the actual rate the spring will produce, it changes the leverage that the shock sees. When calculating the spring rates the angle correction calculations must be used for a difference of 5* of shock angle.

That is why the adjustment of the dog bone on the late model bikes is better. It does not affect the fulcrum of the shock linkage. Yes, it does affect the leverage the shock linkage feels from the swingarm, but that change is much less critical because of the overall leverage of the swing arm as compared to the short leverage of the relay arm that the shock is connected to.

That is why the adjustable links like those made by Soupy's are a great addition for the late model FJ, the early model does not offer this adjustment with the aluminum swingarm linkage.

The shock length should reaming as close to stock as possible. The allows the suspension to operate in the range the linkage was designed to function in. By changing the shock length, the linkage range is compromised in one direction, changing the leverage & load to the shock which is directly related the spring rate & internal shock valving.

Randy - RPM

[craigo]

Being the one that kicked the hornets nest I can say that sums up why I was interested in the adjustment. It is not an adjustment I would be changing all the time, I want to find the sweet spot and leave it.

I bought a Penske with the adjustable ride height option. I found it great for adjusting the ride height to match the various tire profiles. I currently run a 170-60/17 which has a smaller profile than the stock 150-80/16. I plan on a 180-55/17 for my next rear which has an even smaller profile than the 170. The adjustment made up for the reduced rear height.

CraigO

[andyb]

Is it a possibility to change the ride height by changing the shackles on the end of the shock?  You'd not gain any travel, and the shock would remain in the same position in the stroke (minor changes from the weight moving forwards, I suppose).  I'd think within reason this would be an acceptable way to do it?  That would mean that you'd just have to have a removable yoke on one end, and swap to a different one as needed, probably for a minor cost of the replacement, yes?

[racerrad8]

Is it a possibility to change the ride height by changing the shackles on the end of the shock?  You'd not gain any travel, and the shock would remain in the same position in the stroke (minor changes from the weight moving forwards, I suppose).  I'd think within reason this would be an acceptable way to do it?  That would mean that you'd just have to have a removable yoke on one end, and swap to a different one as needed, probably for a minor cost of the replacement, yes?

Yes, that is where the adjustability of the shock length would occur. But, that length does change the fulcrum angles of the swingarm linkage and that is the compromise that I have to be able to justify and compensate for.

I have been asking for it because people keep telling me they "want it", but the manufacture needs to have a justifiable reason to have it like the two listed.

Rear tire/wheel height & steering head angle.

They are experience much more than I am in the design, function and tuning of their product and their concern is having adjustments of the shock that cannot be compensated for without re-valving the shock.

I want to thank everyone for their input and I will be in conversation about the changes in possible design over the future production runs. But at this point, when the shock are bolted on now, I believe most people will not need to adjust the ride height with the proper spring rate and sag. You just cannot compare the stock shock and the issue with it to the new RPM shock.

Keep them coming, it is all information I can educate myself with and work together with the manufacture to make the product better.

I strive to continue to improve all products as time goes on, it is not my intention to make it and just leave it forever. Any changes that are made will be able to added to the shock at the rebuild interval if required/requested.

Randy - RPM

[Mark Olson]

Alright boys, here is the dealio .

I had the opportunity to follow Mike Ramos at the WCR on the hwy 20 rip and grip . He was able to hang with the Nor cal Renegades . Known at the Wcr as the "fast five".

I purposely followed Mike R. so I could see his bike in action with the RPM front and rear set up in action. It performed flawlessly , no unsettled wiggle or big ass bouncy
wiggyness . We were flying and even with the last second quick downshifts to 2nd gear and throttle up reducing corner surprises the suspension took it.

So, to sum it up the RPM stuff works as advertised.

I believe adjustable dog bones would be better than an adjustable length shock. The raising of the rear is necessary just to bring back to stock when you put a low profile 17" wheel on the rear. Those of you who want a better turn in ratio can raise it a little more for your liking.

Monkey Mark has a plan to use the shock linkage from a 89-90 on the earlier 84-87 fj's and says it matches so you can use the later model shock.

I have the race-tech springs and emulators on the front and the penske 3-way adjustable rear on My 86 . I have spent a bazillion hours and thousands of miles getting my fj just the way I like it.

With RPM Randy offering a one size fits all Rear shock I am thrilled . I will be doing a straight up comparison to how it works right out of the box as opposed to literally years of dicking around with the penske. Look for the Muppet Labs report when I am finished.

MarkO     

[fintip]

Alright boys, here is the dealio .

I had the opportunity to follow Mike Ramos at the WCR on the hwy 20 rip and grip . He was able to hang with the Nor cal Renegades . Known at the Wcr as the "fast five".

I purposely followed Mike R. so I could see his bike in action with the RPM front and rear set up in action. It performed flawlessly , no unsettled wiggle or big ass bouncy
wiggyness . We were flying and even with the last second quick downshifts to 2nd gear and throttle up reducing corner surprises the suspension took it.

So, to sum it up the RPM stuff works as advertised.

I believe adjustable dog bones would be better than an adjustable length shock. The raising of the rear is necessary just to bring back to stock when you put a low profile 17" wheel on the rear. Those of you who want a better turn in ratio can raise it a little more for your liking.

Monkey Mark has a plan to use the shock linkage from a 89-90 on the earlier 84-87 fj's and says it matches so you can use the later model shock.

I have the race-tech springs and emulators on the front and the penske 3-way adjustable rear on My 86 . I have spent a bazillion hours and thousands of miles getting my fj just the way I like it.

With RPM Randy offering a one size fits all Rear shock I am thrilled . I will be doing a straight up comparison to how it works right out of the box as opposed to literally years of dicking around with the penske. Look for the Muppet Labs report when I am finished.

MarkO     

[hein]

Hi Randy.

Your comments regarding shock length changes changing geometry are correct. My use and preference for adjustable length shocks are not to make radical changes but to allow for fine tuning. In other words get close with the links and fine tune with the shock length.

Hein. 

[Bozo]

Marko, I fitted the RPM emulators a few weeks ago, before I fitted them the bike was reasonable in the front and not bad in the back (I have a Hagon shock with a hydraulic adjuster).
As I emailed to Randy I think his emulators are totally crap, because the acceptable rear end has now turned into a Mack truck while the front end feels fantastic. I have tried the lot to make the rear behave but the front end always makes the rear "feel" lacking.
All I can say is that Randy better pull his digit out and get that shock on the market (remember Randy, the 1989 model is first)

[Mark Olson]

Marko, I fitted the RPM emulators a few weeks ago, before I fitted them the bike was reasonable in the front and not bad in the back (I have a Hagon shock with a hydraulic adjuster).
As I emailed to Randy I think his emulators are totally crap, because the acceptable rear end has now turned into a Mack truck while the front end feels fantastic. I have tried the lot to make the rear behave but the front end always makes the rear "feel" lacking.
All I can say is that Randy better pull his digit out and get that shock on the market (remember Randy, the 1989 model is first)

well if we could all just agree to adj the ride height with dog bones I think the shock will go into production.   

[fintip]

Might it be easier/cheaper to just sell a dogbone kit and a non adjustable shock than to worry about making the shock itself adjustable? I don't understand exactly how dogbones work, I have to admit, since I've never had a bike that had them and this is my first monoshock bike... So am I missing something?

[Dan Filetti]

I don't understand exactly how dogbones work, I have to admit...

Neither did I -I kept reading that you need to LENGTHEN the dog bones to LOWER seat height...  I was trying to visualize it, until I saw this pic:



This is a BMW shock, but it illustrated the mechanics of it well.

Dan