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Old 05-23-2015, 07:12 AM   #1
Yamarocket630 OP
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Proven, quantifiable benefits of a fork brace?

I know people love their fork braces. I think it's probably for the bling factor, but does anyone have any quantifiable proof i.e. lap times, suspension logger data etc that they actually provide any benefit on a modern-ish STREET bike?

For sake of argument we'll call it a first gen FZ1 which weighs about 500lbs and has 43mm conventional forks.

I had a holeshot fork brace on said bike and removed it because I was tired of the seals seeping from bug guts on the fork legs (you have to remove the "bug deflectors" to install the holeshot brace). So far I have noticed NO change in the bike's handling.
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Old 05-23-2015, 07:20 AM   #2
SloMo228
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I'm sure it depends on the motorcycle in question. I have only ever mounted a fork brace to one bike, a '78 Honda GL1000. It made a very noticeable difference on that bike. Before the fork brace, it always had kind of an unnerving, vague, wobbly feeling in high-speed sweepers and quick direction changes (well, quick for a 500+ pound motorcycle from the '70s, at least). After, it was much more solid and confident-feeling. Some of that may have been all in my mind, but at the same time my dad also had a '77 GL1000 and riding them back-to-back you could clearly tell the difference.

On a more modern bike that already has fairly stiff forks? Maybe it doesn't do so much.

Edit: So no hard data, but back-to-back comparison of two of the same bike, one with and one without fork brace is, I think, slightly better info than a before-and-after seat of the pants comparison on the same bike.
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Old 05-23-2015, 08:53 AM   #3
GeneralGarden
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The FZ1 has an upside down fork with the bigger tubes handling the distortion stress. Maybe the difference is more noticable on bikes with conventional forks.
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Old 05-23-2015, 09:13 AM   #4
Tim_Tom
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They are most noticeable on bikes with skinny conventional forks. While I've never added one to my bikes, I've had bikes with them. On one particular day the front fender, which had the fork brace integrated in it, came unbolted from the left fork leg. Without that structure in place the bikes handling suffered immensely. Wallowing even at a slow pace and it wanted to wander. As soon as I replaced the bolts, and added lock tite, handling was back to normal.

It may be the forks on your FZ1 have enough torsional rigidity that the fork brace is not needed. Or maybe you aren't pushing the limits enough to need the fork brace.

I have no numeric data, but from my observation fork braces are helpful.

I find it odd that bug guts cause fork seals to leak. You are sure the tubes aren't nicked, scratched, pitted etc? Have you tried cleaning the bugs off? Seems easy enough to stick a rag under your seat and fix the bug issues...
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Old 05-23-2015, 12:26 PM   #5
Maggot12
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Had one a 650 strom and it made a noticeable difference. No track proof or anything like that, but more solid front end and no wobbly feel going over road cracks or curb areas.
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Old 05-23-2015, 01:48 PM   #6
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depends

I remember bikes with 36/37mm forks and highly recommended fork braces.
On the fz1oa web site track riders thought it worth while. First generation that is.

Those wheelie prone seem to benefit. Traditionally dirt bikes benefit.

My reading implies you should check fork tubes for run out, and the bushings. Then make certain fork brace fits exactly.

The average street rider, with stock fork and rear shock, May never notice a difference.

The FZ1 is undersprung, usually needs respringing (and a rear shock change) to work properly. After changes do not know if benefits might show up. Or not.

The idea is to keep the suspension equal on both sides of the axle. Do not know if the bikes with damping separated in each fork, use braces, I would expect so.
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Old 05-24-2015, 01:55 AM   #7
PeterW
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Major difference on a DL 650, but mostly off road. It meant I could point the front wheel out of a rut - and guess what , the bike climbed out of the ruts.

Without the brace there's so much flex that the front wheel tended to get stuck, turn the bars, but the wheel hits the side of the rut deflects and won't climb out.

Probably helped on tar snakes and cracks in the road, but off road was the clear win.

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Old 05-24-2015, 03:36 PM   #8
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Makes a huge difference when bouncing over babyhead sized rocks off road and on road it made a difference on the grated briges spanning the big muddy. Other than that it seems the same . Would rather have one than not.
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Old 05-24-2015, 08:01 PM   #9
Yamarocket630 OP
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I was sure happy to get home from my ride today and not have to scrap bug guts off the fork legs and out of the seals. The bike didn't wobble and try to spit me off without the brace either. Almost like the engineers at Yamaha knew what they were doing when they designed the bike without one...
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Old 05-24-2015, 08:13 PM   #10
windblown101
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Quote:
Originally Posted by Yamarocket630 View Post
I was sure happy to get home from my ride today and not have to scrap bug guts off the fork legs and out of the seals. The bike didn't wobble and try to spit me off without the brace either. Almost like the engineers at Yamaha knew what they were doing when they designed the bike without one...
Yeah. I really don't think the Gen1 FZ1 needs a fork brace. At least I never felt the need for one on mine and I rode it a few track days. I'd say you made the right call. Suspension upgrade for valving and spring rates will make a difference you can feel and see on lap times though on the old gal. I weigh about 175lbs and before I had the suspension redone the bike would start to wallow in the corners when pressed hard.

On the other hand. I had an '05 Kawasaki Concours that GREATLY benefited from a properly shimmed and installed fork brace. But I never took it to the track to prove it. ;)
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Old 05-24-2015, 10:09 PM   #11
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A bit anecdotal vs quantifiable but a fork brace on the venereable Nighthawk 750 is pretty amazing. I have put on 2 on mid/late 90's CB750s and done before and after rides.

The forckbrace makes for crisper, quicker, more precise turn-in. It also dramatically improves braking; all but eliminates single-disc pull/twist.

I know that doesn't help with the FZ1 but...
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Old 05-27-2015, 12:28 AM   #12
BorisRoberts
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83 GS1100E, came with a Telefix from the original owner. Bike always rode a little harsh in the front, stiction. I was messing with it one day, decided to loosen the screws on the fork brace. Bam, like a fucking miracle, no more stiction. So, being a MMF, a machining muthafucka, I start measuring. First I pulled the forks off, and chucked them up and checked for straightness , they were pretty close, couple thou, not bad. Them I grabbed the tubes in the chuck and checked how much slop was in the lowers, in relation to the sliders, same thing, not bad, but back then, it was real low miles.

Then I measured the Telefix fork brace. First, I found that when you tightened up the part that clamps to the tubes, they were out of round, and also had an extremely tight press fit, when it was tightened, as I recall (it was back in the 80s), it was about .020 or. 025 under the diameter of the forks themselves. Then I checked how parallel the clamps were to each other. They weren't. When you tightened up the adjuster screws, the clamps twisted. So I installed the forks, I measured between the mounting surfaces on each fork leg, got the fork brace as close as I could get to being the right distance apart, clamped them tight, then bored each mounting clamp to the right diameter (about .002 press fit was what I made them to), then I never unclaimed the center part again, just the outer clamps to put them on. It was like magic, no more stiction. Back then, I had more free time. I figure, that at shop rates, I put at least $1000 in shop labor into those clamps.

So, careful now, those fork braces can actually make things worse.
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Old 05-27-2015, 01:13 AM   #13
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This thread got me interested in researching fork braces. The overwhelming opinion from various bike specific forums is that fitting a fork brace resulted in a significant improvement. The vee-strom seemed to be perhaps the most popular model to fit a fork brace.

Most negative comments (well it seemed to be just about all of them) came from people who actually didn't have any first hand experience themselves. When asked to support a comment they were no good, they couldn't actually provide an answer. Lots of theoretical answers, but no specific experience themselves.

It's clear that a badly manufactured and/or installed one can create a stiction problem if the forks no longer run true, or the forks aren't true to begin with and the brace stops the forks moving to compensate. However, as it seems the procedures for fitting one and checking that the forks move without a problem seem well known, you have to assume anyone who fitted one and experienced a problem was sort of slack in the first place.

P.S. the feedback was positive enough for me to order one for my bike. It does get a little flex in high speed sweepers (+90mph), can't say for certain its the forks. It does react badly to tar snakes and grooved roads which were main areas were a brace was said to make an improvement. At worst it'll do nothing because it would't get out the workshop if there's even a suggestion of increased stiction.

My bikes got fork protectors fitted which will probably have to go. But they weren't standard as I fitted them. I always thought they were to stop stone damage to the chrome fork tube. Pretty dodgy seal wipers if they can't get rid of soft bug crap. I use the outrageously expensive SKF low friction seals and wipers and they do seem to do as claimed (stiction 5mm, 15 is considered ok).

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Old 05-27-2015, 05:01 AM   #14
Yamarocket630 OP
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My problem was getting bugs higher up on the legs above the "normal" travel area. They would dry hard and cause the seals to leak after a big bump or hard braking. Then the bigger bug chunks would stay stuck in the seals and make them slowly weep oil.
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Old 05-27-2015, 06:09 AM   #15
JohnCW
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Quote:
Originally Posted by Yamarocket630 View Post
My problem was getting bugs higher up on the legs above the "normal" travel area. They would dry hard and cause the seals to leak after a big bump or hard braking. Then the bigger bug chunks would stay stuck in the seals and make them slowly weep oil.
There should be no 'above the normal travel area' on a bike, other than the deliberately set 20mm approx buffer zone from completely bottoming out (for street bikes only). It should use all its travel virtually every ride. Firm braking while crossing the gutter into a driveway or gas station, or braking to a stop down a steep hill should be enough to utilize near full travel. I have to reset my permanently fitted zip-tie every time after pulling into a gas station so as not to get a false reading for the rest of the ride.

If its not using full travel, then set the sag, fit correct weight springs, adjust compression damping, and adjust fork oil height till it does. You paid for a certain length front suspension travel, use it.

P.S. I can already hear someone's brain thinking 'fork dive' like its some dirty word. Look at a front-on picture of a MotoGP bike under brakes, there is zero travel left. They don't seem to mind a lot of fork travel per se. They just don't want their forks to uncontrollable collapse because of weak springs and inadequate compression damping.

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