Fork Braces

[YoshiHNS]

after beck's post about the fork brace for the 4th gen's making a big difference, I started doing the math on how much it would cost to machine one myself. For one, probably about the same as the one he posted. But a production run, I'm pretty sure I could get it a chunk under $100 complete. I have access to 4th, 5th, and 6th gen bikes, so I can test fitment without a problem. Just wanted to see if there was any interest in any of these for me to even see what it would cost to do a run and how complete the product should be.

[Beck]

Here's another successful run of the waterjet program I made for a VTR, which will also fit the 4th gen:

That looks fantastic Seb!

It looks as stiff as a steel bridge That 1 piece design will have ZERO flex. I might just have to upgrade mine to whatever you guys come up with once the design is finalized! :fing02: :blush:

Beck

95 VFR

[Ryanme17]

But don't the VTR braces fit the 3-5 gens? Don't get me wrong, I'd much rather buy a custom piece from a VFRD member than an Asian-made E-bay piece, but it seems you'd have most interest in 6th gens, as there is no option out there, and most members on here are 6th gen owners.

I would definitely be interested--if I weren't unemployed at the moment...

[fastbroshi]

Hate to put the horse before the cart here, but has anyone ever bothered to, uh, prove that fork braces have a beneficial effect on street-ridden motorcycles? A real test, not simply anecdotal evidence...

Ciao,

Are you asking us the members of the forum this? Because I doubt any of us has the resources and know how to do so. I'm sure manufacturers have done this real testing in the past. Heck I remember Honda used to put fork braces on their custom/cruiser bikes' forks in the early 80s, replete with logo on the front. I'd be willing to bet money that their findings were that traditional style forks, not usd, like those on VFR's do indeed flex and would benefit from a brace. This given amount of give was most likely written off as acceptable within the service life of the forks and wouldn't distort them permanently, etc.

Could they be made stiffer? Sure, but at added cost or redesign. Would we notice through our hands and butt-mounted g-meters the difference? Sure, but not enough to make the bean counters accept the added cost.

You really don't need evidence. We all know two HOLLOW steel shafts approx. 2-3 feet long will flex. Oh, wait, the fork assembly is made of separate cylinders that make them longer? Surely they wouldn't be prone to flex.

I'll trust others that say it works. Those that say a Type - R sticker makes them faster, not so much.

[Monk]

I'd also add that if they are useful they are probably on the racing bikes(I'll have to start looking for them at the races).....

I had one added to an old 72 Honda 360, and it made a lot of positive differences.

[JZH]

Hate to put the horse before the cart here, but has anyone ever bothered to, uh, prove that fork braces have a beneficial effect on street-ridden motorcycles? A real test, not simply anecdotal evidence...

Are you asking us the members of the forum this? Because I doubt any of us has the resources and know how to do so. I'm sure manufacturers have done this real testing in the past. Heck I remember Honda used to put fork braces on their custom/cruiser bikes' forks in the early 80s, replete with logo on the front. I'd be willing to bet money that their findings were that traditional style forks, not usd, like those on VFR's do indeed flex and would benefit from a brace. This given amount of give was most likely written off as acceptable within the service life of the forks and wouldn't distort them permanently, etc.

Well, I'm curious if anyone has done any kind of testing, actually. Yes, Hondas used to come with OEM fork braces...and spindly forks. Some people might conclude that if Honda no longer considers fork braces necessary on modern sport motorcycles, they aren't. Amusingly, the fork brace manufacturers seem to rely on breathless testimonials and comical animations, rather than any kind of rigorous testing. Maybe Motorcycle Consumer News will one day do a fork brace "shootout", using one of their skilled testers in a "blind" test...

Could they be made stiffer? Sure, but at added cost or redesign. Would we notice through our hands and butt-mounted g-meters the difference? Sure, but not enough to make the bean counters accept the added cost.

The added cost of a mass-produced OEM fork brace can't be very much--assuming that's all it would take to put the bike at the top of the supersport heap, surely Honda would have done it back when the CBR600RR debuted. What they actually did was fit 45mm conventional forks--quite a bit more expensive than slapping a fork brace on the F4i's 43mm forks, eh? (Sorry, that's an anecdote! :ohmy: )

You really don't need evidence. We all know two HOLLOW steel shafts approx. 2-3 feet long will flex. Oh, wait, the fork assembly is made of separate cylinders that make them longer? Surely they wouldn't be prone to flex.

I admire your ability to so convincingly employ conventional wisdom in place of science! :laugh:

I'll trust others that say it works. Those that say a Type - R sticker makes them faster, not so much.

No comment! :blush:

Ciao,

[YoshiHNS]

ok, i've been a bit busy at work wiring a machine. Hopefully get the measurements and prototypes done this week. I like the thought of a one-piece design, but for sheer convenience I think I'll go with two, though making it one piece won't be too much extra work. I'll do the math on the shear of a 1/4" screw, but I have a feeling it's going to be good enough.

[SEBSPEED]

But don't the VTR braces fit the 3-5 gens? Don't get me wrong, I'd much rather buy a custom piece from a VFRD member than an Asian-made E-bay piece, but it seems you'd have most interest in 6th gens, as there is no option out there, and most members on here are 6th gen owners.

I would definitely be interested--if I weren't unemployed at the moment...

The 6th gens also have stiffer/better forks to begin with, I've only experienced my VTEC forks flexing under the hardest of circumstances, on very twisty roads running a very hard pace, or while taking my chicken strips off within a single lane. In those circumstances I don't mind having a bit of flex. Don't forget the engineers know that the forks flex and take that into consideration when they design the chassis. They should have SOME lateral give to them.

[SEBSPEED]

Yoshi, do you want a .dxf file of the brace I have? You can play with that and make it 1, 2, 5 pcs, whatever. It will at least get you the slider and spacing dimensions to start with.

[YoshiHNS]

A .dxf file would be great. Was just going to ride the two bikes down to the shop and get the measurements there. Did you design that to have a bushing between the fork and brace? I saw the Coerce had a nylon bushing or something.

[Beck]

A .dxf file would be great. Was just going to ride the two bikes down to the shop and get the measurements there. Did you design that to have a bushing between the fork and brace? I saw the Coerce had a nylon bushing or something.

I think the bushing is a particular design approach by the manufacturer that can be deleted on other fork brace designs. I think they used it to deal with possible tolerance differences between different fork units, but the density of the material seems to be enough to get a good hard grip on the slider tops. The Telefix fork brace I installed on my Hawk GT came with thin strips of aluminum for shims instead I assume for the same purpose/reasons.

BTW, I think JHZ won't ever be satisfied unless someone sets up a jig with strain guages and lasers to quantify the added stiffness that fork braces add to the fork assembly. Sorry, but I don't have the funds or tools to do that. All I can say is, this is the second bike I installed a brace on and there definitely is an improvement with fork action, stiction reduction and resulting compliance. Went riding the twisties again yesterday and the front wheel tracked perfectly through the trip with the tires staying on the road giving me good feel and control through the bumpiest turns........but I guess, for some, my body and brain isn't a sensitive enough instrument to make that judgement...not even after over 30 years of riding all sorts of bikes in all sorts of conditions doesn't make me some sort of motrocycle chassis expert.........I guess that's a valid opinion I could respect......In the end, you don't have to buy a fork brace for your bike if you don't want to....

Beck

95 VFR

[The Phantom]

The 6th gens also have stiffer/better forks to begin with, I've only experienced my VTEC forks flexing under the hardest of circumstances, on very twisty roads running a very hard pace, or while taking my chicken strips off within a single lane.

Taking your chicken strips off within a single lane... :laugh: :blush:

We need video, Seb...

Once when out on a multiday ride, I jumped off a 4th Gen with a well-sorted front end (valving, springs, oil all modded and tuned) onto a stock brank new Vtec - first and only time I've ever ridden one - and the improvement in feel of the front end was immediately obvious. I eventually decided that it was mainly down to the beefier 43mm forks rather than anything else as there isn't a huge amount of difference in the internals between 4th and 6th Gen AFAIK. Note that prior to riding the Vtec I'd just done the best part of 2000km of 7/10ths fanging on tight bumpy mountain roads, so was pretty well tuned into how I wanted the bike to behave. I was impressed.

So, given that the VFR is a road bike and not a racebike, and is designed and built accordingly (and for a 60-70kg rider to boot!), anything that can help with overall stiffness is a good thing in my book - and as an additional thought related to the above, I don't think Vtec owners will see an improvement with a fork brace that is of the magnitude of that which a 3rd-5th Gen owner may see.

I appreciate JZH's point, it's quite valid, but if we assume that the fork brace provides *some* additional stiffness and helps tie the front end together just a little more, then when you combine that with a bunch of other small improvements you get an overall result that is obviously going to be a) better than just a fork brace on a stock front end) and b) perhaps something that is more than the sum of its parts... so, you do springs, oil, valving, new wheel bearings, fork set correctly in tripleclamps for minimum stiction, correctly balanced tyre with the right pressure setting for its type and your riding style - and voila, good sex front suspension! :ohmy:

[SEBSPEED]

Taking your chicken strips off within a single lane... :laugh: :blush:

We need video, Seb...

I'm sure it looks real squidly, but it's fun and good practice for avoiding surprises in the road. :ohmy:

[FotoMoto]

This is one of those discussions where both sides have points but don't know where exactly to agree. :biggrin:

In my experience (no scientific jig building here!), anything below 41mm can benefit from a brace while anything above 41mm goes into the money best spent elsewhere category. And this isn't forgotten 80's tech. My 98 bandit 1200 had a hidden one built into the front fender mount. FWIW

To any doubters, I say this: buy one for $120 (or whatever), mount it (it's super easy), ride it, and if you don't think it's worthy, sell it on a forum for $90-100 and it will be gone in a day! :dry:

[Ryanme17]

Hate to put the horse before the cart here, but has anyone ever bothered to, uh, prove that fork braces have a beneficial effect on street-ridden motorcycles? A real test, not simply anecdotal evidence...

Ciao,

Suspension is an art, not a science. I'm not sure how you'd quantitavily test something like this, anecdotes seem about the best one could get.

[JZH]

Hate to put the horse before the cart here, but has anyone ever bothered to, uh, prove that fork braces have a beneficial effect on street-ridden motorcycles? A real test, not simply anecdotal evidence...

Suspension is an art, not a science. I'm not sure how you'd quantitavily test something like this, anecdotes seem about the best one could get.

I am not suggesting fork braces don't make forks stiffer--from their design it seems like they would have to--though a question remains regarding the sufficiency of the stiffness that already exists. I'm simply questioning whether "additional stiffness" is something worth having on a street-ridden sport-touring bike. For (anecdotal) example, the guy who suggested I perform an experiment on my ST1300's OEM 45mm forks, using safety wire, clearly expected the forks to bulge sufficiently at the top of the fork lower tubes to break the safety wire, which would have proved his point. However, this did not happen under even the most punishing London speed bump-attacking I dared. So, from a layman's perspective, either there was no substantial bulging to be arrested by a fork brace, or I somehow managed to achieve the benefit of a £100 fork brace for the price of some safety wire... :biggrin:

(BTW, fork braces could be tested the same way they test tyres. Get someone who could literally feel a pea on the road and have him (or her majesty) ride the same bike several times over the same course at increasing pace whilst not knowing whether the fork brace was installed or not for each run. Download rider impressions after each run and collate and analyse at the end. The truth will out.)

Ciao,

[SEBSPEED]

JZH, were you going over those speed bumps at a decent lean angle, while in a turn?

I am NOT trying to stir anyone's pot by asking, please don't take it that way. When I think of fork flex, the first thing that comes to mind is lateral(side to side) flex. So, in a left lean for example, the forks would flex to the right, with the left becoming shorter and the right longer, causing misalignment and stiction due to the axle being the only bridge. In hard left/right transitions, I experience the forks twisting beneath my hands. A fork brace would help deter these forces, more so in the first scenario, although certain design changes could be made to eradicate the twisting as well.

Now, to your point, as to whether or not this is truly beneficial or merely an ease on the mind; I can't prove it to you one way or the other with hard evidence. I will say that the theory sounds damn good though, and has common sense written all over it. I would be more concerned with analyzing the forces transferred to the steering head and neck of the chassis, as well as the subsequent raise of force on the swingarm pivots. All the physics are still at play, they're just being moved to another part of the bike by adding the brace.

Again, to me, it's not truly a matter of what exactly the brace by itself does, but rather how it affects the chassis as a whole.

[V4 Rosso]

Suspension is an art, not a science. I'm not sure how you'd quantitavily test something like this, anecdotes seem about the best one could get.

I don't think having a major in art gets you a job at the R&D department of e.g. WP or Öhlins. A degree in mechanical engineering might Also ask yourself if you have evers seen fork braces in the catalogues of reputable suspension tuners. I am not saying that a brace is not beneficial for a pre vtec front suspension, It's just that when I read the claims made by the people who sell them I get a feeling they have no real clue about suspension either.

It is not that difficult to test the impact a brace has on the front suspension. Put the bike on a hydro-pulse and you can measure fork flex in any direction. Also fork sticktion, and the effect a brace has on fork sticktion, is something that can be measured whith the fork riding over simulated bumps.

JZH, I am not surprised the safety wire din't break, it is much too flexible. Maybe replacing it with a carbon string has a different outcome. Like you, I find the superbrace animation a bit comical. It only shows sideways flexing of the forks, nothing about the forks bending back and forth when riding over bumps or when braking. I have a slow motion video of that somewhere, maybe I can dig that up. Amazing to see how much older forks used to bend under heavy braking. So the claim that superbrace eliminates (all) fork flex is total BS imo.

When I think of fork flex, the first thing that comes to mind is lateral(side to side) flex. So, in a left lean for example, the forks would flex to the right, with the left becoming shorter and the right longer, causing misalignment and stiction due to the axle being the only bridge. In hard left/right transitions, I experience the forks twisting beneath my hands

I can't imagine the forks flexing much because of lateral load. If what you describe would happen than you will likely have more problems with brakes sticking. The forks will not be equaly loaded when going through a turn, your fork brace design can cope with that a lot better than the low profile braces like the superbrace. But isn't what you are experiencing more of a torsional flex with the wheel out of alignment with the bars?

[Terminex]

A couple items that came to mind throughout this post:

1 - I am one of the poeple who would be interested.

2 - I think the reason the other makers went with a 5 piece design is for ease of installation. (trying to get the center piece of a 3 piece mount installed could be VERY challenging and mess up the paint / finish on the fork, IF you can even get it in there somehow)

3 - One thing that has not been brought up yet is "the weakest link". When you stiffen up the front fork at a certain area, you are removing some of the play that MAY have been designed into the fork. i.e. the old bend vs break idea.

4 - this leads me to my next idea. if worried about the shear strenght of the 1/4 inch bolts, it may be BETTER to use a 5 piece design. that way you can ensure that one of the bolts would break BEFORE one of the fork legs buckles BELOW the fork brace due to the increased load applied to that location.

5 - I raced Mtn bike for a long time. Back in the beginnning god created Mtn bikes....... (sorry tangent) No, really when I started riding mtn bikes, the front fork HAD to have fork braces on them because they had so much flex in them. As time went on, you no longer needed the fork brace as they were designing them to better. This does not mean that I think the 6th gen is perfect, quite the contrary, they have done a wonderful job of making it better, FOR 150lb riders. when you get someone my size (215) or bigger, then your are putting more weight, which equates to MUCH more force on the forks.

Sorry, I know I ramble on some times, but if I don't get these thoughts out, then I have other bad thoughts.........

[SEBSPEED]

When I think of fork flex, the first thing that comes to mind is lateral(side to side) flex. So, in a left lean for example, the forks would flex to the right, with the left becoming shorter and the right longer, causing misalignment and stiction due to the axle being the only bridge. In hard left/right transitions, I experience the forks twisting beneath my hands

I can't imagine the forks flexing much because of lateral load. If what you describe would happen than you will likely have more problem with brakes sticking. The forks will not be equaly loaded when goign through a turn, your fork brace design can cope with that a lot better than the low profile braces like the superbrace. But isn't what you are experiencing more of a torsional flex with the wheel out of alignment with the bars?

Yes, sorry, two different thoughts going at the same time there. I don't have a problem at all with "normal" riding. The hard left/right stuff isn't really a problem either, but it does bother me to feel that torsional flex happening. Now I could just stop doing that... or?

[Insomniac]

I don't know anything about torsional flex or lateral stability, or the like. I DO know that when I look down through the fairing at the forks when I'm under hard, controlled braking and see the forks wiggle front to back, maybe a fork brace may help.

Just my 2cents.

Jeff

[Beck]

Heck, the 4th gen forks are so wimpy that I could actually see it twist just when sitting on the bike and looking down the fork leg from above and just putting al little pressure on the handlebars to turn left or right. I could see the bars turning before I see movement of the wheel and tire below to the direction I am turning the bars towards. It was actually after I saw this that I decided to go ahead and find a brace for my 4th gen. After installation I did the same test and I cannot see the same twisting anymore . I do not think that 100% of the twisting is eliminated, it is impossible to do so with any mods on the front end. Materials will always have some flex to them, but it has been reduced to the point that I cannot detect it by sight anymore as I did before installing the brace.

Beck

95 VFR

[Brown81]

Heck, the 4th gen forks are so wimpy that I could actually see it twist just when sitting on the bike and looking down the fork leg from above and just putting al little pressure on the handlebars to turn left or right. I could see the bars turning before I see movement of the wheel and tire below to the direction I am turning the bars towards.

Beck

95 VFR

Yep, me too. As cool as it would be to have a "scientist" or "science" confirm it, it's not a requirement. Being able to see it when just sitting there, and then mentally adding 2-3G of decell, couple with a 500lb bike and a 200 lb rider, all going around a bumpy tight turn......hmmm.. yep, I think they are flexing. A LOT.

Just a guess, no science to back it up. :rolleyes:

[Knife]

Sorry, I know I ramble on some times, but if I don't get these thoughts out, then I have other bad thoughts.........

And it also keeps the voices in your head at bay.

[V4 Rosso]

5 - I raced Mtn bike for a long time. Back in the beginnning god created Mtn bikes....... (sorry tangent) No, really when I started riding mtn bikes, the front fork HAD to have fork braces on them because they had so much flex in them.

Or was it because back then all ATBs had rim brakes as opposed to discs. HS33 brakes are still frequently fitted with an extra brace, or brake booster as they call it.

I DO know that when I look down through the fairing at the forks when I'm under hard, controlled braking and see the forks wiggle front to back, maybe a fork brace may help.

A fork brace will be the least effective in that direction.

It was actually after I saw this that I decided to go ahead and find a brace for my 4th gen. After installation I did the same test and I cannot see the same twisting anymore .

That explains the many positive testimonials for better low speed handling.

[JZH]

JZH, were you going over those speed bumps at a decent lean angle, while in a turn?

No, I wasn't. I'm willing to fly the flag for science; I'm not as willing to die for it!

I am NOT trying to stir anyone's pot by asking, please don't take it that way. When I think of fork flex, the first thing that comes to mind is lateral(side to side) flex. So, in a left lean for example, the forks would flex to the right, with the left becoming shorter and the right longer, causing misalignment and stiction due to the axle being the only bridge. In hard left/right transitions, I experience the forks twisting beneath my hands. A fork brace would help deter these forces, more so in the first scenario, although certain design changes could be made to eradicate the twisting as well.

If this were the primary design goal, I would think the braces should be designed to be a thick as possible--like 25mm--at the clamps. Most designs seem to be dealing with the "bulging" non-problem. This lack of direction probably stems from a lack of analysis concerning the exact problem the design is supposed to solve...

I wonder if Larry's experience with fork bushing shims would be informative w/r/t the "designed-in" slop in the front suspension? Unfortunately, I can't remember his conclusion! The only other consideration I can think of is whether the fork brace would be manufactured to more precise measurements than the triple clamps it works with--if the measurements are not an exact match with the existing parts, the fork brace could actually create stiction where there was none before...

Ciao,