[kidwoo]

Facts from 2014 (caution, metric units):

Told you there's a reason I'm holding onto my 2013 40.

I will NOT be Ruxxed up.


edit: translations are fun

Trophy or hospital - a winged word among downhillers. And it is also a good fit: our test track in the Bikepark Bad Wildbad is a nightmare.

I need to go to more bikeparks named Bad Wildbad.

 

[slimshady]

I need to go to more bikeparks named Bad Wildbad.

How about Badly McBadFace?

 

[iRider]

Told you there's a reason I'm holding onto my 2013 40.

I will NOT be Ruxxed up.

But RUX is moar stiff and, as we all know, moar is always better! Ask your GF.

 

[kidwoo]

But RUX is moar stiff and, as we all know, moar is always better! Ask your GF.

Mines a different chassis son

 

[Kanye West]

Ahhh I love me some actual data in the early morning.

So, the twisting stiffness of a Dorado is half that of a 40 or whatever else. It is also 25-30% stiffer in pure bending fore/aft. Let's assume for the time being there's a similar margin for bending left/right.

Which of these represents the on-trail behavior of the front end of the bike in a corner? And...once you choose, explain HOW. Explain where the leverage and load path come from.

UDI, this should give you a Godzilla-sized boner right now. I bet that keyboard is going to be piping hot once you're done.

 

[Sandwich]

I remember reading once that a USD fork would get stiffer through its travel due to increased bushing overlap as it compresses. I was never really confident how the physics would play out in such an instance.

is there any reason a USD fork couldn't be made to work well and be adequately stiff? I like my 40, but I can comfortably say I don't need MOAR stiffness in a downhill fork. Less would be acceptable at times. Instead of a carbon Fork Arch to Resist Torsion (FART), could you simply do a bigger axle and externally braced upper tubes?

 

[Kanye West]

I remember reading once that a USD fork would get stiffer through its travel due to increased bushing overlap as it compresses. I was never really confident how the physics would play out in such an instance.

That's only if you have a bushing attached to the stanchion that telescopes inside the upper tube. No such system in mtb forks at this time.

 

[kidwoo]

USD forks wander like a mother fucker when your front wheel catches the sides of things and when grabbing or breaking traction and moving laterally. Any idiot who's ridden one knows this and you don't need hoffdata™ to justify trying to ignore that fact by pretending all impacts are 100% head on.

Might buy another one if it has a 100mm diameter axle.

 

[Mo(n)arch]

That's only if you have a bushing attached to the stanchion that telescopes inside the upper tube. No such system in mtb forks at this time.

But leverage gets lower. Theoretically the fork gets stiffer the deeper it gets in the travel. Not really helpful, though.

 

[djjohnr]

I had a recent Dorado set to 180mm that never gave me a serious problem with wandering. On the other hand I remember demoing a single crown Shiver that was like having a random direction generator strapped to the front of the bike.

 

[Jm_]

This is a cool picture of me from a long long time ago. The best part was almost crashing when I landed because the fork went whatever way it wanted to in the rough. Dangerous as fuck.

 

[Jm_]

But leverage gets lower. Theoretically the fork gets stiffer the deeper it gets in the travel. Not really helpful, though.

Helpful in MX when you are casing 40 foot doubles.

 

[kidwoo]

when you are casing 40 foot doubles.

Pay closer attention to women's WC DH




Boom! That's right. I'm goin to hell.

 

[Jm_]

Pay closer attention to women's WC DH




Boom! That's right. I'm goin to hell.

Now we'll have "innie"(verted) and "outtie" forks....

 

[Udi]

is there any reason a USD fork couldn't be made to work well and be adequately stiff? I like my 40, but I can comfortably say I don't need MOAR stiffness in a downhill fork.

Sure, if you want to take what you're happy with and make it heavier, flexier, and inferior.

 

[Happymtb.fr]

Sorry for an on topic break but Probikeshop who is selling spare parts for Bos just messages on a French forum that there is some press material to be released regarding how Bos has been working on improving customer support, availability of spares and communication.

It sounds like a well needed improvement and let's hope they do it right.

 

[konastab01]

Dont care how flexy these are I really want them or maybe the ohlins ones if they actually come out.

 

[William42]

Whats harder on a fork? A ~200lb ish dude like Brook McDonald shralping a rock garden, or a 120 lb girl like Mannon shorting a 40 foot double and casing the shit out of it? Which one do you need your fork to be uber stiff for?

 

[slimshady]

Going back to the other French guys in this thread, seems like the CRConception guys are using square stanchions/bushings:

 

[norbar]

Sorry for an on topic break but Probikeshop who is selling spare parts for Bos just messages on a French forum that there is some press material to be released regarding how Bos has been working on improving customer support, availability of spares and communication.

It sounds like a well needed improvement and let's hope they do it right.

Impossible. I've heard they still use the guillotine in France for people who offer good customer support

 

[troy]

Impossible. I've heard they still use the guillotine in France for people who offer good customer support

Viva la bushings resistance!

 

[Happymtb.fr]

Going back to the other French guys in this thread, seems like the CRConception guys are using square stanchions/bushings:

Not quite sure he uses that, he showed something with guiding keys too on his facebook...
https://m.facebook.com/photo.php?fbid=1324249094326998&id=260667494018502&set=a.261080027310582.63809.260667494018502&source=54&refid=13&ref=page_internal
https://m.facebook.com/photo.php?fbid=1324248977660343&id=260667494018502&set=a.261080027310582.63809.260667494018502&source=54&refid=13&ref=page_internal

 

[sethimus]

i only run 3 bolts on my rotors so i guess i already win?

only if you use hollowed out ti bolts

 

[Udi]

@slimshady
@Happymtb.fr
I meant to say this (forget if I did or not since maybe it's super obvious?), but square/keyed bushings are a bad idea, because it means that the reaction force against torsional flexure force (i.e. the cause of any stiffness benefit) is ALSO the normal force in the friction equation.

This means each time you have torsional forces going through the fork (which is most of the time in MTB), you're driving sliding friction through the roof. You also get some nasty localised loadings at the stanchion/bushing interface, so premature wear is likely. It's not a good idea for performance in the short term, or durability in the long term.

Of course you get a much smaller version of this scenario in any circular-bushing fork too but the effect is much less (and less localised) because the parts are free to rotate against each other. It's always best to increase stiffness via non-sliding interfaces which is why the arch of a normal fork's casting works very well (as would a huge 35-40mm axle if we were OK with heavier hubs and nonstandard parts).

 

[slimshady]

Yeah, I know the leverage against the bushings would mean the stanchions could basically lock out momentarily if the tolerances aren't tight enough. I think the main reason some brands resort to this solution is to keep the weight tolerable for a given stiffness goal.

 

[Jm_]

I think the main reason some brands resort to this solution is to keep the weight tolerable for a given stiffness goal.

No, it's because they are Cannondale and they will find some way to f*ck up simple shit.


However, the left is about the perfect solution for fatbikes IMO. I saw that new manitou fork and it has the largest brake arch on earth, ever, 6+lb fork.

 

[Happymtb.fr]

forget if I did or not since maybe it's super obvious?

Sometimes it is good to say some obvious things!

It is a tuff call for small producers willing to enter the fork market: either you invest a lot of money into expensive casting tools multiple times because there are several hub, tires and wheel sizes or you go the USD-way which give you plenty of flexibility, a much smaller investment and some other technical drawback do deal with...

 

[StiHacka]

This thread needs moar gold.

 

[StiHacka]

and skin

NSFW

 

[sethimus]

 

[toodles]

News outlets seem pretty excited about Formula's new DH offering as well. Plus Formula have set up a Canadian distributor based in Whistler so looks like they're ready to make some moves into North American market.

 

[WestCoastHucker]

This thread needs moar gold.

lol. Ohlins Muh-FGR...

 

[Trekrules]

BOS Obsys Details

• 220mm travel
• Air sprung
• 42mm stanchions
• Wheel size: 27.5" or 29"
• Externally adjustable rebound, low-speed compression, air preload
• Boost 20 x 110mm spacing
• Weight: 3180 grams (claimed)
• Price: TBD

https://www.pinkbike.com/news/bos-suspensions-new-inverted-fork-and-coil-shock-eurobike-2017.html

 

[Kevin]

An obsys and a syors... thats the best they could do? Really?

 

[troy]

An obsys and a syors... thats the best they could do? Really?

"Obsys" means obsolete in french. And the other one is just a misspelled "Sorry".

 

[kidwoo]

An obsys and a syors... thats the best they could do? Really?

You were hoping for "punchystix" and "dampydoodle?"

 

[WestCoastHucker]

then at least everyone in the room would say it correctly...

 

[StiHacka]

if I put a 26'' wheel on it will the lizards take me away or will a black hole open?

Yes.

 

[toodles]

New DVO conventional fork coming - http://www.vitalmtb.com/features/DVO-Introduces-New-Singlecrown-Dual-Crown-and-Air-Shock,1987