Downside to Correct Fork Sag

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Finished installing my Gold Valves this week, and as part of the process of rebuilding (replacing all wear parts) in my front forks, I checked the sag before, increased the length of the preload spacer, and checked it afterward.

First, I want to thank everyone who I pestered with questions - on the phone, and via PM's. And anyone who commented in my other threads about this project. You were all a great help! The project turned out to be a success (see my Review of the Gold Valves).

I weigh right around 170# with ATG. Before sag was measured at 49mm. After increasing the preload spacer 1/2" my sag ended up at 38mm. In other threads, sag of 36 to 40mm is considered optimum so I hit the nail on the head - thanks to dduelin's formula of about 1.2 x desired reduction in sag. It worked - the formula said to increase my spacer 13 mm so I did 1/2 inch. Right on the money!

Only problem (and this is tongue in cheek) is the bike now rides a bit higher than before exacerbating touching down at stops. I couldn't flat foot the bike before, now it's a bit worse at off camber stops.
 

DavidR8

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I can respect what you are saying.
If I forget to reduce the rear preload after a two-up ride I'm always surprised by the difference in seat height.

My Tiger was really tall for me. I was only ever able to flatfoot it when we were two up. If I forgot to drop the preload afterwards it was downright alarming.


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dduelin

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The trade off is worth it. Correct ride height, correct steering geometry, additional cornering clearance, improved damping and rebound valving is way better than loosing a little reach to the ground and you can buy an eBay side stand and have a welder build up the foot to reduce the now greater lean when on the side stand.
 

CruSTy

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It may be possible to off set some of the height gain. The forks can be moved approximately 1/2' up in the triple trees. The sag and fork travel will not be affected by the but it effectively lowers the front. 2 caveats. Be sure you are clamping the upper triple tree on the machined portion of the fork tube. If you have a gen 2 or 3 bar riser you may not have room to do this.
Chuck
 
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dduelin

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It may be possible to off set some of the height gain. The forks can be moved approximately 1/2' up in the triple trees. The sag and fork travel will not be affected by the but it effectively lowers the front. 2 caveats. Be sure you are clamping the upper triple tree on the machined portion of the fork tube. If you have a gen 2 or 3 bar riser you man not have room to do this.
Chuck
I forgot about this. By raising the forks in the clamps it is possible to gain back about 5 mm with the OEM bars and same with the MCL risers I have.
 
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I don't know how much of the handling difference is due to the gold valves themselves, and how much is due to the change in chassis orientation from reducing the sag. But, if you drop the fork tubes by 5mm that is the same as increasing the sag 5mm in terms of chassis orientation, so you've negated half of that change if you drop them.
 

CruSTy

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I don't know how much of the handling difference is due to the gold valves themselves, and how much is due to the change in chassis orientation from reducing the sag. But, if you drop the fork tubes by 5mm that is the same as increasing the sag 5mm in terms of chassis orientation, so you've negated half of that change if you drop them.
I think most of the gain comes from getting the preload and sag on the springs correct. How much rake would you loose by moving the the forks up 5-10mm? I honestly don't know. It is an easy adjustment and can be put back just as easily if he doesn't like the result.

Chuck
 
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On the other hand, it is easier to get the bike on the center stand!

I did the same upgrade over the winter (front and back) and am very happy with the results--pretty much transforms the handling and ride.

Dan
 
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I don't know how much of the handling difference is due to the gold valves themselves, and how much is due to the change in chassis orientation from reducing the sag. But, if you drop the fork tubes by 5mm that is the same as increasing the sag 5mm in terms of chassis orientation, so you've negated half of that change if you drop them.
I'll probably leave things as they are until layup for winter. Worst case is I get some more practice dropping the bike. And, I haven't pushed the bike and myself enough yet to notice a handling difference. What is literally startling is the smoothness of the ride and the response of the front end over bumps. Another way to describe it is take your bump, and stretch it out so the rise above the pavement is not so abrupt but a ramp. Some of these seem to be taken by the forks in slow motion. I doubt very much this is due to getting rid of half an inch of sag.

On the other hand, it is easier to get the bike on the center stand!

I did the same upgrade over the winter (front and back) and am very happy with the results--pretty much transforms the handling and ride.

Dan
Silver lining to every cloud....I'd noticed this but did not put 2 n 2 together.
 

wjbertrand

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As set up from the factory the Honda fork has too little spring (excess sag) and too much compression damping (harshness). Honda also runs the fork oil quite high which reduces the "air spring" volume at the top of the fork and makes its progression very steep, again adding harshness. Both the high compression damping and high oil fill probably help resist bottoming due to the fork riding too low. With proper sag, enough travel is regained to better handle bumps without bottoming and the compression damping and oil fill level can be backed off to smooth the ride out. Night and day difference when I did mine.
 

DavidR8

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With proper sag, enough travel is regained to better handle bumps without bottoming and the compression damping and oil fill level can be backed off to smooth the ride out. Night and day difference when I did mine.
Do you mean when you did your Gold Valves or set sag and oil fill levels?
 

dduelin

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Do you mean when you did your Gold Valves or set sag and oil fill levels?
Running slightly lighter weight oil, proper sag set with preload, and OEM oil level worked great for me at 165 lb riding weight. The lighter oil eases the harshness of the OEM valving and the oil level allows full suspension travel without bottoming.
 

DavidR8

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Running slightly lighter weight oil, proper sag set with preload, and OEM oil level worked great for me at 165 lb riding weight. The lighter oil eases the harshness of the OEM valving and the oil level allows full suspension travel without bottoming.
This might be the setup for me. I'm about 175 lb riding weight and find the forks to be pretty harsh.
 
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On the oil part, I was under the impression you went up from a 5wt to 7.5 wt? I did and it seems fine, maybe a little easier on the bumps. BUT, I did go from PR4's to 011 Shinko's which I don't like at all. No shimming. I'm 215 with gear. I have no problems with the handling short of the tires.
 

Whooshka

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On the oil part, I was under the impression you went up from a 5wt to 7.5 wt? I did and it seems fine, maybe a little easier on the bumps. BUT, I did go from PR4's to 011 Shinko's which I don't like at all. No shimming. I'm 215 with gear. I have no problems with the handling short of the tires.
I'm already itching for the spring ride. Now that we're more familiar with the bikes we can push a little harder and really get to compare. And throw Bryan's into the mix. Maybe Ron too? LOL
 
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I pushed my fork up the triple clamp by 10mm ( about 1/2") , that is the maximum. I have gen 3 Heli bar rasier. This is to compensate for a 1" shorter rear shock. This bike rides like fatory except it sits lower. I played around with the fork position before installing the shorter rear shock. The effects were very noticeable.
Kenny
 

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