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What Kinda Bike Is That?
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Discussion Starter #1 (Edited)
For the past two seasons, (2008 and 2009), I have had rubber fork gaitors mounted to the front forks of my bike. I like them from the standpoint of the protection they provide to the forks and seals.

But I have learned, they significantly reduce the suspension performance of my bike due to my style of riding.

Last year, as I was riding the Route du Nord, (250 miles of dirt road between The James Bay Road and Chiboumagau), I thought my motorcycle was going to completely vibrate apart!

Scott and I were trying to move at a fast clip. The Route du Nord is a fairly well maintained road, (we passed two road graders working the "kinks" out of the dirt surface), but there are some nasty "washboard" sections. Scott on his big GSA BMW, with his cantilever front end suspension, could cruise smoothly across the rough stuff. I on the other hand, spent most of my time standing up on my footpegs, trying to keep my teeth from rattling out of my head! One casualty that did occur was that my GPS sheared right off of its base, (However, I do need to mention, at that time, there were already about 50,000 miles of abuse on that GPS base).


Still, I felt something was wrong. It felt like I was getting "short changed" on my suspension.

This past winter, while doing this year's bike modifications, (The full build thread is HERE), I decided to do some research on the issue.

I jacked up the front end of my motorcycle and removed my fork caps. Using a ratcheting strap, I pulled up the front wheel just as far as I could go; compressing the fork gaitors just as much as I could. This is what I saw.


Next, I dropped my forks, pulled the fork gaitors off of the fork tubes and shoved the forks back up; again, compressing the forks as much as I could. This is what I saw.


I then took a ride on the bike, with an electrical zip tie wrapped around one fork tube. I rode on a fairly rough, dirt road, at a fast clip, intentionally hitting potholes; trying to recreate the Route du Nord experience.

I didn't take a photograph, but my dust wipers left the zip tie just under 1" below the bottom fork clamp.

I calculate, by having the fork gaitors mounted, I end up losing about 1 1/4" of fork travel. That could have helped me out a lot on the Route du Nord.

I have sinced removed my fork gaitors from my bike. I need the extra travel.

Food for thought.

Thanks,

Barry
 

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FORUM GODFATHER.....R.I.P. PAT
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My gaiters are protecting the ABS brake line junction under the triple clamp.:mrgreen:
How much, if any, are your forks extended above the triple clamp?
 

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What Kinda Bike Is That?
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Discussion Starter #3 (Edited)
My gaiters are protecting the ABS brake line junction under the triple clamp.:mrgreen:
How much, if any, are your forks extended above the triple clamp?
1/2".

So, I am losing even more travel. But, I think my measurements are relative. With the forks slid up 1/2" and the fork gaitors installed and removed during my measurements, I lose about 1 1/4" of travel.

(There is more coming in the 2010 Bike Modifications thread. This excersise was fender related. I am writing that up now and will post it shortly.).
 

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Do your forks actually compress that much with the springs in them and the air pocket at the top of the oil? It would be interesting to put a threaded rod through the spring, fender washers & nuts on each end, and compress the spring to measure its compressed length. Figure this length above the damper rod to the spacer and see how much compression is possible not counting the effect of the air cushion.

One consideration with the fork gaiters...they can hold heat in. The hydraulic dampers in the forks convert the kinetic energy of the bouncing front wheel into heat energy*. That's how they do their damping. If the heat is trapped in the dampers the oil will thin and less damping is the result. Could this be happening to you?

*"...energy can neither be created nor destroyed, it can only be transformed from one state to another."
http://en.wikipedia.org/wiki/Conservation_of_energy
 

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FORUM GODFATHER.....R.I.P. PAT
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The suspension action pumps air in and out. If they were air tight, the compression stroke would blow them up.
 

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I don't use gaiters for all the reasons stated so far that have negative resullts.:headbang: This is what I came up with.
What it is, is a piece of a mud flap (rubber about 1/8 to 3/16' thick) riveted to the inside surface of the "BAT EARS" on the front fender. You have to take the fender off to rivet them on, but it's easier than putting gaiters on. No it will not protect the shocks in very muddy areas with other bikes spraying your bike. Yes it will protect your shocks from any debris that come at them from the front of the bike. (about 200 degrees of coverage) They allow the shocks to cool, they do not restrict their travel and they do not ever rub on the shocks.:hurray:
 

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Can I nominate Honest Bob for some kind of Penny Tech award? Fork Flaps. What a good idea!
 

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Can I nominate Honest Bob for some kind of Penny Tech award? Fork Flaps. What a good idea!
Can we hold the Award Ceremonies in Las Vegas? :green_lol:
 

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Perhaps I am thinking at it the wrong way, but I would have said that the rough ride you experienced was due to harsh high speed compression damping rather than travel. How much travel do we really use over washboard?
 

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What Kinda Bike Is That?
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Discussion Starter #10
If readers go back and read my original post, I explained that, I "re-created" the situation, WITHOUT the fork gaiters installed and with a electrical zip tie strapped to my fork tube. The tubes compressed over the rough terrain that I was riding on; leaving the zip tie at its "highest" point of compression. That point is ABOVE the point where my forks are fully compressed with the fork gaiters installed.

The result of the above clearly has informed me that, fork gaiters are not for me and the kind of riding that I encounter. My forks have been definitely bottoming out against my fork gaiters; restricting the distance I COULD have without the fork gaiters installed.

In 2008, I changed from the OEM front fork setup, to .90 Sonic Springs and 12.5w fork oil. I have also tried 10w and 15w. Again because of the "softer" ride that I want to deal with some of the rough terrain I ride on, (And, it is not just all dirt! Have you ever ridden on Maine's roads during the early Spring months? Lots of frost heaves.), in 2009, I added Race Tech Gold Valve Emulators. For 2010, I have the original Suzuki fork springs installed, 10w fork oil and the emulators. It is a nice soft setup up for my needs.

The addition of the fork gaiters compromises that setup. I have removed them for the mentioned reasons.

B.
 

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What Kinda Bike Is That?
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Discussion Starter #11
Perhaps I am thinking at it the wrong way, but I would have said that the rough ride you experienced was due to harsh high speed compression damping rather than travel. How much travel do we really use over washboard?
In New England, you need lots of travel. Particularly in the Spring time.
 

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Have you experimented with different oil levels so you have more or less air cushion in the forks? More fork oil has less air in the forks for more cushion on deep compression--right?
 

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FORUM GODFATHER.....R.I.P. PAT
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Less air would increase the effective spring rate as it would be harder to compress the smaller volume.
 

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What Kinda Bike Is That?
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Discussion Starter #14
Have you experimented with different oil levels so you have more or less air cushion in the forks? More fork oil has less air in the forks for more cushion on deep compression--right?
I don't think you are understanding my point; the application of fork gaiters impede fork travel, as opposed to not having them installed.

To me, Fork oil weights, fork oil level, spring rate, emulators are all INSIDE the forks and they ARE doing what they are designed to do, for my setup. The fork gaiters are on the OUTSIDE of the forks, and for the kind of riding I do, they inhibit fork travel for me.

Someone riding smooth pavement is not going to have the issues that I have experienced and described.
 

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Rjsurfer
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I purchased a set of fabric gaiters somewhere that come together using some velcro so they go on easy.

Ron W.
 

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I definitely get what you're saying about the fork gaiters impeding full fork travel. Where I'm getting lost is how that applies to washboard roads. I think that you and I have differing ideas of what constitutes "washboard".

You are experiencing the issue over what I have heard referred to as "frost heaves"? What constitutes "washboard" to me is small, close set, bumps; not the long wallows. We don't have the freeze/thaw cycles like you probably do, so I'm not used to your terms for road conditions.

I think I am picturing your issue better, now that I (hopefully) have a better idea of what you mean.

At any rate, I'm glad you figured out the point of failure for your set-up.
 

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What Kinda Bike Is That?
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Discussion Starter #17
I definitely get what you're saying about the fork gaiters impeding full fork travel. Where I'm getting lost is how that applies to washboard roads. I think that you and I have differing ideas of what constitutes "washboard".

You are experiencing the issue over what I have heard referred to as "frost heaves"? What constitutes "washboard" to me is small, close set, bumps; not the long wallows. We don't have the freeze/thaw cycles like you probably do, so I'm not used to your terms for road conditions.

I think I am picturing your issue better, now that I (hopefully) have a better idea of what you mean.

At any rate, I'm glad you figured out the point of failure for your set-up.
My personal experience with "washboard" surface conditions is this; the rapid succession of closely spaced "bumps" causes the suspension to "pack" down. As the front wheel comes in contact with each quickly repeating bump, the front suspension can't rebound fully.

Essentially, the forks take a "hit", slightly rebound before the next hit. And, on it goes....... Because the forks don't have a chance to completely rebound, (or fully extend back out to a normal setting), the situation causes the suspension start to "pack". Which in turns starts to move up the tubes, effectively eating up suspension travel to where it is gone; or where the travel is impeded by fork gaiters.
 

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FORUM GODFATHER.....R.I.P. PAT
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Pack down implies too much rebound damping. You might try a lighter weight oil.
 

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What Kinda Bike Is That?
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Discussion Starter #19
Pack down implies too much rebound damping. You might try a lighter weight oil.
If I remember correctly, I think I may have been at 15wt, (with .90 Sonic Springs) on the Route du Nord. I am now at 10wt with the OEM springs back in the tubes. I will see what happens.

For what the Route du Nord can be like, running it at a fast clip, I would have preferred to be on a more "dirt oriented" suspension equipped motorcycle, (or a cantilevered BMW).

The experience felt like, I can keep up the speed, the bike can keep up the speed, but there is something "wrong"; a weak link in the system.

Maybe sort of described as, you are on a sailboat, there is a good breeze blowing, the sails are trimmed fine, but you know that you aren't moving at the speed you SHOULD be moving at. You look over the transom and what you see is, a lobster pot warp wrapped around your prop shaft. Effectively, you are dragging along 3 lobster traps under "perfect" conditions. That will slow you down!

Again, by making the measurements of my fork tubes compressed with and without the fork gaiters and riding over a rough road with a zip tie wrapped around a tube, and taking that measurement, I know that I have been bottoming out on my fork gaiters.
 

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FORUM GODFATHER.....R.I.P. PAT
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But now that you have full travel back, you can see if the bike is packing down and do something about it if it is.
 
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