Nitron Piggybacks.

Good work Vince. I also noticed the change from a minor decrease in comp damping on my Nitrons. Should be a breeze to go too far then reverse to the goldilocks spot.
 
Do you know the feeling when your banging your head against a brick wall with glazed eyes and nothing makes sense? I am still getting way too much bottoming so I emailed the supplier to see if I have the right springs fitted. My build sheet lists 125/ 150 lbs springs. I get an email back and get told I could try a 175lb spring so I agree, but for some crazy reason, it's one spring only. I am thinking this bloke doesn't have a clue, he thinks it's a mono-shock bike so I ring and learn some really interesting info. I thought 125/150lbs would be 2 springs on each side stacked on top of each other, I've seen exactly that on my old Husky twin shock Olhins. But NO, it's a 125lb spring on one shock and a 150lb spring on the other, that's why I am only getting ONE spring. I have the choice of replacing the 150lb spring with the 175lb new one and going one step harder or replacing the 125lb spring and going 2 steps harder. Pretty clever design, but who knew if you were not told? It works to split the spring rate to get more adjustability, similar to those forks that dampen in one leg and spring in the other. Its annoying there manual says nothing about this.
 
I was thinking about how important getting the correct spring rate is and how I have struggled doing exactly that over the years. Never got a good result from using spring rate calculators. It always comes down to suck it and see. Reminds me of seeing Troy Bayliss testing at Eastern Creek a few years back when he was returning to The Oz Superbikes, his Suspension Tech had a huge cart filled with shock and fork springs and they were changing springs just about all day.
 
I';m surprised to hear that Vince. My Nitrons were set up for a 1200 (so laid fwd triple). I'll check the spring info on the specs card that came with them. I wonder if odd spring rates could cause unwanted twist in the swingarm? I'm pretty happy with mine, all I've done is adsome preload to reduce my sag a little. I need to do a proper spring test session out of town somewhere - ditto for the front USDs.
 
I was surprised as well, BUT if your outside the typical weight range of 60 to 80kg it apparently takes a coin toss to get the correct springs. It's exactly the same for non-symmetrical fork internals, I guess it's not perfectly balanced between the 2 and requires either the triple trees or swingarm to compensate. I did some simple calcs, the difference between the spring rates the shocks came with averaged between both springs is 137.5 lbs originally, the potential next rate is 150 lbs, up 12 lbs. The next is 162.5 lbs, up 25 lbs. It's going to take less preload to get the correct Sag and hopefully less bottoming and a more compliant ride. That seems counterintuitive but that's what happens with harder springs that use less perload.
 
I have never heard of different spring rates each side. Anyone else?
I also thought it was damping divided between the forks. Compression one side and rebound the other?
 
Some modern forks only have springs in one side, and only damping in the other. These Nitron shocks are built individually in the factory in England, they select the springs used from your data and fit them.
 
Tippie said:
I have never heard of different spring rates each side. Anyone else?
I also thought it was damping divided between the forks. Compression one side and rebound the other?
Click to expand...
It's common practice in modern forks.
My Maxton'd forks have compression in one leg and rebound in the other.
Fine tuning of the preload may require differential spring rates in either leg, but only by the next rate, up or down.
 
A
Vince said:
I was surprised as well, BUT if your outside the typical weight range of 60 to 80kg it apparently takes a coin toss to get the correct springs. It's exactly the same for non-symmetrical fork internals, I guess it's not perfectly balanced between the 2 and requires either the triple trees or swingarm to compensate. I did some simple calcs, the difference between the spring rates the shocks came with averaged between both springs is 137.5 lbs originally, the potential next rate is 150 lbs, up 12 lbs. The next is 162.5 lbs, up 25 lbs. It's going to take less preload to get the correct Sag and hopefully less bottoming and a more compliant ride. That seems counterintuitive but that's what happens with harder springs that use less perload.
Click to expand...
If the force of the impact with a bump is below the spring preload then you have a strut, not a spring.
 
I am about to swap in the 175lb shock spring I got from Shocks Are Us, the Oz Nitron distributor to attempt to stop the bottoming issue I have been having. Because of the way these are supplied, I can go 1 step harder or 2 steps depending on whether I change the spring on the right side of the bike from Std 150lbs to the 175lb spring, which will result in an increase of 12lbs overall, or I swop the left side spring from std 125lbs to 175lbs and that ends up at 25lbs stiffer overall. That 2nd change ends up at twice the work as I need to return the first change to std and then proceed with the next change if the first change doesn't fix the excessive bottoming. I know this sounds complicated and counterintuitive but I have done the maths and it's all possible as in this case you get as supplied a 125lbs spring on one side and a 150lbs spring on the other shock. I went looking for the spring compressing tool I bought a few years back. It's in 3 bits and I couldn't remember how it worked, thankfully I found it on sale and they had a picture. I will after the job cable tie it together so I don't forget how it works next time. It's a great gadget that is pretty cheap but works really well.

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Mmm, horns of a dilemma. I do have a positive way to measure the effect, cable tie on the shock shaft. Your probably right, big changes are much more noticeable. Besides I can blame you if it doesn't work. Win-win. Wink wink
 
Found something interesting today. Finally made a start on the spring swap. I used to be able to remove long dirtbike springs by using 2 large screwdrivers through the springs and crushing them enough to get the upper clevis out. That wouldn't work on both Maz and Icon short road shocks cause I couldn't crush them enough by hand so I bought that spring compressor I showed a couple of posts back. Today I discovered Nitrons have so much thread for perload adjustment winding it off compression allows the spring to be completely free. It's held in with a circlip so doesn't need compression to hold a clevic in place. I hope it goes as easy as it looks.
 
Did you have the grub screws on the threaded collars done up when they were on the bike before, Vince? It seems a pretty weak way to lock them, but I guess it works. I seem to recall Carlo saying his were threaded collars were not locking firmly in place. Speaking of whom, haven't heard from Carlo for a bloody long time.
 
Yes, I carry a Jewler's slotted screwdriver to nip it up, very easy to miss it being in one of the multiple preload tool holes around the collate. The shock owners manual is pretty basic, they could have easily doubled the pages with relevant info if you ask me. Plus some language is ambiguous, for a company based in England, it almost reads like those old Italian Translations everybody used to laugh about. When I was on the phone with Shocks are Us the distributors learning about its oddball dual spring info I was told about the spring ID numbers etched into a coil that also has the spring rate. I was in a hurry and just turned the springs by hand without releasing the plastic grub screw. It was pretty easy to do but I guess it might in time buggar the fine preload threads. I was surprised they don't use 2 collates like every other shock builder ever. Carlo lives in Murrarundi about a 150ks south of Tamworth. He turns up on a few of our 2 day country rides, the last time I think was either the Bellingen Rally or the Oxley Hwy Brass Monkey last year. Just another old member here missing in action I guess.
 
Finally fitted the new spring, I was dreading it but surprisingly it was really easy. 20 minutes had it done and dusted. I went for the harder of the 2 options. It probably won't bottom now, set the sag by eye on the cable tie fitted to the shock shaft to 30mm or 1/3 of travel. I did the seat bounce test and it's pretty firm, didn't go beyond the last 25mm of travel, not even close to bottoming. Hope that the last 25mm gets used on a test ride or it will be too hard and that means double the work to go back to the softer of the 2 options. We have a predicted week of rain so no test ride for a while. I also hope that the same test proves my guessable spark issues are fixed as well. The last 2 rides resulted in sudden engine cutouts and refires, bloody dangerous in the local heavy traffic. Fingers crossed it's 2 birds with one spring test.
 
Finaly found a day without rain or 40c temps and managed a few laps around the block to test the new springs and its a lot firmer, to firm actually. The cable tie on the shock sharft stopped approx 10mm off bottoming which would be ok, except that block has a bunch of very big speed humps. Those speed humps should have resulted in some bottoming. Coincidenty I read a post by Terry Hays about using cable ties to test travel.

Quote
Tying Yourself In Knots…..
The use of zip ties as travel indicators has become common place these days, but beware….. they can be a double edged sword.
They can be a useful tool when used thoughtfully but do have the capacity to create confusion…. as well as damage.
They “Will” tell you how far your suspension has travelled but unfortunately not “How Often”.
So if you were travelling from Sydney to Melbourne on your road bike, you could be spending most of your time hovering within the middle of the suspension range and then you pull into a petrol station to re-fuel.
There could be a spoon drain or perhaps a speed hump that almost completely compresses the fork. You don’t give it any thought at the time….. Next thing you’re sitting in a café in Melbourne and looking at your bike (obviously a Tri Colour Monster)
and you notice that the zip tie is right at the bottom of the fork…. Shit!. My suspension is bottoming out!
Choking on your latte….you go hurriedly searching through your Ducati back pack, rumbling through your Ducati T shirts, Ducati sunglasses and sneakers to find your Ducati Iphone so you can call Frasers roadside assistance. Come quick!!! My shocks are bottoming out!!!
So in this case the full travel was used only once and under exceptional circumstances…..not the norm.
Some people also make the terrible mistake of putting a zip tie on a shock absorber shaft, once again to monitor suspension travel.
This is almost always done without the knowledge that the bump rubber is part of the suspension travel. Bump rubbers are generally about 15 - 20mm thick and extremely compressible. This can potentially represent up to 30 - 40mm of rear wheel travel.
So your zip tie could hit the bump rubber and you still have a lot of travel left. Or the zip tie will hit the rubber, the rubber compresses and expands again, pushing the zip tie back up to the top of the bump rubber, potentially disguising actual suspension movement.
If this happens repeatedly, the zip tie often tears the bump rubber, which ultimately leads to its destruction.
A similar thing can happen with the dust seals on the forks. If your normal fork travel sees the dust seals right at the bottom of the tube on full bottom out, then the addition of a zip tie quite often will destroy them. (Travel 1 in diagram)
Some fork tubes bottom out whilst still leaving a portion of chrome tube exposed. (Travel 2) There could be 15mm of chrome tube still showing with the fork fully compressed. In this case the zip tie will do no damage but if you aren’t aware of where the bottom out position actually is, you could have a false impression of where you are in the stroke.
I would prefer to see people use an o-ring on their forks rather than a zip tie. They are far less offensive to the fork and more pleasing to the eye…..just be very cautious when making your assessments.



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Double the work double the fun. I returned the original shock spring back onto the left shock and replaced the right side spring with the new one supplied by Isse at Shocks are Us, so it now has one one-step stiffer spring rate instead of 2 steps. The latter was not good, very firm and it also had the bike jacked up on the rear a touch. It felt a bit less stable. It probably will be a while before I test it, it's 40c tomorrow and then we get a week of wet weather.
 
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