4Th Gen: Front Fork Brace Or Cbr600 F3 Forks?

[V4 Rosso]

There was a pretty good animation of the different ways the forks bend in a turn and under braking and that, and what a fork brace helps with. It was exaggerated, but if the forks bend out 0.010" the bushings will have to take that force, which increases stiction.

It is one of those animation that makes me sceptical about the use of those braces.

First of all it starts with their perception of what a speed wobble looks like

Second, where does that torsional flex com from. It is very hard to turn a fast rotating wheel because of the gyrocopic forces. When riding you hardly turn the bars and when some outside force generates so much torsional flex it can only be because the rider has a death grip on the bars. Also the lateral flex in the direction shown in the video is negligable compared to the lateral deflection perpendicular to that direction, due to ouside forces like the weight of the bike, road bumps and braking.

But I am sure these braces can be beneficial when installed properly because when not (or of poor quality) they supposedly have an adverse effect as stated by e.g. Progressive Suspension:

5. Fork Braces: We have found numerous cases of binding

forks due to improperly mounted fork braces. Our

experience has led us to conclude that even the slightest

misalignment while installing the fork brace will cause the

forks to bind.

Also I have never seen these brace being produced or sold by reputable suspension tuners, only by shops that sell all kinds of motorcycle bling. But although I am very sceptical I would be interested to try one and experience myself if, and by how much, a fork brace makes a difference.

[Veefer800Canuck]

The longer a structure is, the more it will tend to deflect with forces applied in certain directions.

Bracing the object near it's midsection will reduce bending moments, but only in certain planes, according to how the brace is installed (direction) and the direction of the force applied.

As I look at the installation of fork braces, they would somewhat stiffen the structure from steering stem to axle, but not so much in the fore/aft directions. So under braking, it would be of little benefit.

Forces acting to twist the wheel away from the centerline of the bike to the left or right would be resisted more with a brace than without.

But by exactly how much, and is that really measurable or noticeable on a streetbike, enduring street forces, I don't know.

Certainly USD forks are far more resistant to flex than "regular" forks, due to their larger diameter at the triple clamps.

So short answer long, I think they may help, but I can't quantify it.

[V4 Rosso]

I think this one sums it up pretty good: " It allows you to get rid of the front fender without losing the integrity of the suspension."

[SEBSPEED]

Certainly USD forks are far more resistant to flex than "regular" forks, due to their larger diameter at the triple clamps.

And because of the greater amount of overlap between the inner and outer tubes.

[JZH]

There was a pretty good animation of the different ways the forks bend in a turn and under braking and that, and what a fork brace helps with. It was exaggerated, but if the forks bend out 0.010" the bushings will have to take that force, which increases stiction.

It is one of those animation that makes me sceptical about the use of those braces.

First of all it starts with their perception of what a speed wobble looks like

Second, where does that torsional flex com from. It is very hard to turn a fast rotating wheel because of the gyrocopic forces. When riding you hardly turn the bars and when some outside force generates so much torsional flex it can only be because the rider has a death grip on the bars. Also the lateral flex in the direction shown in the video is negligable compared to the lateral deflection perpendicular to that direction, due to ouside forces like the weight of the bike, road bumps and braking.

But I am sure these braces can be beneficial when installed properly because when not (or of poor quality) they supposedly have an adverse effect as stated by e.g. Progressive Suspension:

5. Fork Braces: We have found numerous cases of binding

forks due to improperly mounted fork braces. Our

experience has led us to conclude that even the slightest

misalignment while installing the fork brace will cause the

forks to bind.

Also I have never seen these brace being produced or sold by reputable suspension tuners, only by shops that sell all kinds of motorcycle bling. But although I am very sceptical I would be interested to try one and experience myself if, and by how much, a fork brace makes a difference.

The fork brace business essentially died when 41mm cartridge forks became standard back in the 1990s, because they were no longer considered necessary. I don't know if SuperBrace still uses it, but they used to have an animated GIF that showed a set of (un-braced) forks ballooning outwards under normal movement--absolutely hilarious. [Found it: http://www.pashnit.com/pics/products/superbrace/simulation.swf] Considering there's basically no objective evidence that these things work, you'd think they'd make extra special efforts to appear credible...

Thanks, Rosso, for the Progressive Suspension commentary--I had not seen that before, but I'm not surprised.

Ciao,