Adjustable Preload Fork Caps

[dduelin]

No really I do. I added 16 mm of preload to my ST1300 getting the sag right and like you I am sure the fork is stiffer despite knowing the physics.

It used to dive hard under braking and settle alarmingly in fast turns and doesn't anymore. That is from starting higher in the stroke but the feeling is less dive I guess because the bike is riding higher in it's stroke to begin with.

 

[Cagedodger]

That's pretty much exactly what I meant. It doesn't actually change the spring, but it does start you out in the stiffer part of the spring. Semantics.

 

[DanWill]

Don't over think it, the preload compresses the spring, the more preload the more the spring is compressed. The more the spring is compressed the more force is required to overcome the compression and make the spring move, hence the stiffer feel. Less preload=smoother initial movement of the spring. More preload=harsher initial movement of the spring(the stiffer feel)...

 

[670cc]

Don't over think it, the preload compresses the spring, the more preload the more the spring is compressed. The more the spring is compressed the more force is required to overcome the compression and make the spring move, hence the stiffer feel. Less preload=smoother initial movement of the spring. More preload=harsher initial movement of the spring(the stiffer feel)...

Don't mean to argue, but I think there is still a misconception here. If you apply preload it simply raises the bike. It doesn't compress the spring as long as there is still suspension travel available. Up until the point where the physical limit of the fork tube extension is reached, the spring will still be the same length. Once the fork is at full extension, further increasing preload will finally begin to compress the spring . Go try it.

Or, imagine the front of the bike with no fork tubes, no wheel. The bottom triple clamp is just setting on an open air coil spring that's placed vertically on the floor. The spring is compressed some amount based on the weight of the front end of the bike. Now you walk up and insert a spacer, perhaps a block of wood, between the top of this spring and the triple clamp. Does that compress the spring more? No, the weight of the bike hasn't changed, so the spring remains the same length. (OK, a little compression happens because of the weight of the wood block). The spring rate, or stiffness, remains the same as it is defined by the spring characteristics (Hookes law F=kx, where F is the force, x is the compression distance, and k is the constant factor characteristic of the spring, its stiffness). The bike is simply raised higher into the air by the thickness of the spacer you added, but the spring stiffness is unchanged.

Greg

 

[L.B.S.]

Threaded Spring Preload

"...Increasing Spring Preload moves the spring further into its travel and makes the shock “feel” stiffer initially, and makes the chassis sit a little higher (less sag/more ride height)."

"... Spring Pre-load and spring rate - CHANGING PRE-LOAD DOES NOT CHANGE SPRING RATE. You don’t get a stiffer spring by adding pre-load. Rather you change the weight point at which the spring starts to move. Once the spring starts to compress it will move at its spring rating."

See to me, the distinction begins to blur between "yes it does" and "no it doesn't", depending on which paragraph one chooses to highlight, and a theoretical versus empirical take on it.

Again, I'm way not a suspension dude, but this pretty much is how I've always thought, anyway: Adding preload increases ride height, check. Adding preload doesn't technically change the spring rate, even though it can make the suspension feel stiffer, check.

Beyond that, my eyes start to glaze over to be honest

 

[pdorman]

Hey guys, I just got my preload caps and would like to install them. The prior referenced video shows a direct install without any tube cutting. My bike is pure stock on the shocks so i just need to know if I have to cut the the tubes or not just to install the preloads? I can see the height difference between the stock caps and the preloads, so it would make sense to cut the tubes down to where the preloads fully out would be about the same as the caps and then your adjustment would be what the range of the preloads offer at that point. If the ranges adjustment on the preloads is not enough fully down then I can see cutting the tubes shorter. So 'To Cut' or not 'To Cut' Thanks

 

[Bodysnatcher]

Hey guys, I just got my preload caps and would like to install them. The prior referenced video shows a direct install without any tube cutting. My bike is pure stock on the shocks so i just need to know if I have to cut the the tubes or not just to install the preloads? I can see the height difference between the stock caps and the preloads, so it would make sense to cut the tubes down to where the preloads fully out would be about the same as the caps and then your adjustment would be what the range of the preloads offer at that point. If the ranges adjustment on the preloads is not enough fully down then I can see cutting the tubes shorter. So 'To Cut' or not 'To Cut' Thanks

You can go the route that I did and don't cut anything yet. Just back out the adjuster screw to the limit, swap the caps, and then add (more) preload as desired. Keep in mind that you'll need to apply some force to get the new caps started as they do start out longer to start and hence the immediate increase in preload. If once you get it back together you need more preload then adjust both caps equally until you get where you want it. If after putting the caps on fully backed off gives you more preload than you want only then maybe cut the tubes.

 

[L.B.S.]

If I were to have done things differently (actually I probably will still go that route) is to measure out what the stock spacers are, and replace them with PVC pipe. I would buy enough to make a few varied choices, like .75", 1", 1.25" shorter tubes etc., (whatever approximate zone you are aiming for) and simply swap them out versus wondering if the choice I made to cut was enough, then cut them, only to think maybe I shouldn't have cut more after all, lol.

I raised my front wheel quite a ways off the ground, so there ended up being virtually zero spring pressure on the fork caps.

 

[duk2n]

Hey, L.B.S. I would like to know, three months after you installed the preload adjusters, how are they doing? Do you still like them?

 

[L.B.S.]

Hey, L.B.S. I would like to know, three months after you installed the preload adjusters, how are they doing? Do you still like them?

I'm happier than I thought I would be with them, to be honest. I had expected more of a: "set once and never touch again" type of result. ie: much room for the placebo effect, always wondering if they truly made any difference or not.

In the spirit of full disclosure, I admit I haven't ridden over any particularly gnarly off road terrain, or a super long distance with them yet, but I will report back if I have a good or bad or indifferent experience as I put more intense rides in.


What makes me happier than I thought I would be, is strange, but true.


Where I park at home, I have to squeeze under a low overhead deck. The deck joists are covered with a corrugated plastic soffit material, as well. Under normal circumstances, my bike barely fits under the deck by about literally 1mm with the (stock) windscreen in the low position. I have to lean the bike over, or push down on the suspension a little, to roll it out or back under, without the windscreen catching.

When I put the Intiminator valves in the forks, it effectively raised the front of the bike by about 3/4 of an inch, and my bike wouldn't fit under the deck without total removal of the windscreen. Cutting the stock preload spacer tubes down by about 1", and then installing the preload caps, I can dial in the "slack mode" and drop the bike back down just enough that it fits under the deck again, without worry of breaking the windscreen off, and with a few twists of a socket or wrench, increase the preload back up before going out a day ride or longer trip. Best of both worlds!

 

[duk2n]

LOL, well, at least they serve a purpose!

I'm happier than I thought I would be with them, to be honest. I had expected more of a: "set once and never touch again" type of result. ie: much room for the placebo effect, always wondering if they truly made any difference or not.

In the spirit of full disclosure, I admit I haven't ridden over any particularly gnarly off road terrain, or a super long distance with them yet, but I will report back if I have a good or bad or indifferent experience as I put more intense rides in.


What makes me happier than I thought I would be, is strange, but true.


Where I park at home, I have to squeeze under a low overhead deck. The deck joists are covered with a corrugated plastic soffit material, as well. Under normal circumstances, my bike barely fits under the deck by about literally 1mm with the (stock) windscreen in the low position. I have to lean the bike over, or push down on the suspension a little, to roll it out or back under, without the windscreen catching.

When I put the Intiminator valves in the forks, it effectively raised the front of the bike by about 3/4 of an inch, and my bike wouldn't fit under the deck without total removal of the windscreen. Cutting the stock preload spacer tubes down by about 1", and then installing the preload caps, I can dial in the "slack mode" and drop the bike back down just enough that it fits under the deck again, without worry of breaking the windscreen off, and with a few twists of a socket or wrench, increase the preload back up before going out a day ride or longer trip. Best of both worlds!

 

[GsVs]

I'm sure it has been covered before ... but how does one torque down the original handlebar bolts with the Rox Riser in the way ??

Thanks ...

Finally got around to installing my Rox Risers too. Thankfully, now that I have the Rox installed, I don't have to touch the bars again when I remove the preload caps later, to shorten the spacer tubes down some more.

View attachment 10119

View attachment 10120

 

[elizilla]

When I put the Intiminator valves in the forks, it effectively raised the front of the bike by about 3/4 of an inch, and my bike wouldn't fit under the deck without total removal of the windscreen. Cutting the stock preload spacer tubes down by about 1", and then installing the preload caps, I can dial in the "slack mode" and drop the bike back down just enough that it fits under the deck again, without worry of breaking the windscreen off, and with a few twists of a socket or wrench, increase the preload back up before going out a day ride or longer trip. Best of both worlds!

You could have gotten the best of both worlds, cheaper, by letting the air out of the front tire to park it.

 

[L.B.S.]

I'm sure it has been covered before ... but how does one torque down the original handlebar bolts with the Rox Riser in the way ??

Thanks ...

The Rox put the bars up high enough to get at the bolt heads with a box or open end wrench, but not a common torque wrench* or socket. On my F800, which used external Torx head bolts, I couldn't get at two of the four , so I had to snug up the front two as much as I could and still rotate the bars into position, and then tighten the two lower ones that I could get at. In three years of fairly rugged use, I never once had the bars move.

With my NC, I could tighten all the bolts easily, but the bars have upon occasion, moved in the clamps. Strange, but true. I will slightly roughen up the smooth aluminum of the Rox clamped sections as others have reported doing, with a good result.



*You can use one of several different methods of open end torque wrench adaptors on the market easily enough, but frankly I don't get that concerned about a lot of fasteners on my bikes as far as religious torque spec adherence. YMMV of course, I don't condone anything that contravenes the correct procedures one should follow in this regard.

 

[L.B.S.]

You could have gotten the best of both worlds, cheaper, by letting the air out of the front tire to park it.

They often say the simplest solution is the best alright, lol

 

[SergeantChuck]

They often say the simplest solution is the best alright, lol

But what they don't say is the simplest solution is often the cheapest.

 

[Deleted member 1183]

Don't mean to argue, but I think there is still a misconception here. If you apply preload it simply raises the bike. Greg

I agree. However I recently upped the preload on the shock of my NC. I ended up with a higher back end but also a plusher one. Reason was that the stroke of the damping rod of the shock was increased by my loading the spring, and this allowed the damper to have a greater range of travel to work with, as opposed to the shorter range applicable with a seriously sagged spring where the shock was frequently squatting on bumpy backroads and not able to function properly.

I think the fork preloaders are nice items. They function as they should, and provided there is sufficient travel available in the forks damping rods, they could possibly make for a plusher front end. However, I have never been a fan of just raising the front end of a motorcycle alone as this always increases the fork angle. That is sometimes good for high speed stability but almost always detrimental to the bikes ability to turn quickly, unless the rear is raised by the same amount at least .

I have consistently concentrated on the back end of most of my bikes with regards to suspension, as a basic adjustment. A too low back end does not suit the NC. Because the shock on the NC is not easily adjustable from a preload point of view, many of these bikes are too low at the rear. If owners were to raise them they would find a quicker steering motorcycle which is more fun on a back road. Just try it. I suggest at least two full turns of the preload collar to begin with.

The adjustments I make to my forks on any of my bikes is addition of an air release valve to let the build up of air out, and/or a new set of progressive springs to improve the fork action. If such springs raise the front end then I compensate equally or a little more, on the rear. Most of my suspension adjustments are "seat of the pants". That has worked for me for years. This bike has budget suspension and if I had to rely on it solely for my motorcycling I would replace the fork-springs/oil and the shock, with something more up-market. Basically the preloaders alone are only a minor adjustment of basic units.

These are just some thoughts from my own experiences and not an attempt on my part to impose my views on anyone. Hopefully they will be of some assistance.