[HardtailHack]

Yeah but it can work like one spring with two different spring rates which is what you want, it should ride and pop like a normal DH bike but with better traction and less funky weigh shift when you get airborne. Having a 2kg+ wheel come to a dead stop when you get off the ground isn't really desirable if you can slow it before it hits full droop it should make the bike easier to handle, that's what my inner e-engineer thinks anyways.

I really like the idea but I think it should just be worked in to the shock, or even something similar to the mount like those weird Bioncon bikes.

I like that he mentioned elastomers in the vid, still makes me think April fool's.

 

[Scrub]

From the negative travel demonstration on the video it would seem to be useless to even pull up on the bars to hop over an object, just point and plow downhill. Think about it, if you tried to bunnyhop over anything with that bike, the rear would want to stay on the ground. right? This may work for a moto-x bike instead where there is a motor powering the wheel.

 

[joeg]

From the negative travel demonstration on the video it would seem to be useless to even pull up on the bars to hop over an object, just point and plow downhill. Think about it, if you tried to bunnyhop over anything with that bike, the rear would want to stay on the ground. right? This may work for a moto-x bike instead where there is a motor powering the wheel.

but how do you measure BB height and HT angle????

I remember there was this company that tried to do this with a bike that had more travel than most others and....

...yeah.

shoulda added more shox.

and no: compressively wound springs and more springs in line don't work out because of reality. I know it seemz awesome and soundz great.

 

[HardtailHack]

I still like the idea, the only good feature of a Kowa fork was the negative travel and for the three minutes they worked they felt really really good across the chop. Variable spring rate coils could work really well but most people play with leverage curves instead of messing with coils. There should be no reason that this bike would suck more than a 10" VPP bike it's just a different method to achieve the same ride characteristics.

The more people hate this the more my inner hipster wants one.

 

[4130biker]

and no: compressively wound springs and more springs in line don't work out because of reality. I know it seemz awesome and soundz great.

Well then inform us. This place is way more fun when people with knowledge share it.

 

[maxyedor]

springs in series work like one spring. http://en.wikipedia.org/wiki/Series_and_parallel_springs

Yes, but that's where sliders and coil-stops come into play. Spring1+Spring2/2=primary rate, until one spring enters coil-bind or the slider hits the coil-stop, at which point the race jumps to the main coil's rate.

Lets say your dual-rate Curnutt had a short 25lb spring, and a long 300lb, and the coil-stop was set to lock-out 3" into your 9" of rear travel. Your spring-rate from full extension through the first three inches of travel is 81.25lbs, which would feel like "zero" in terms of handling, after that secondary coil locked out, it would ramp back up to 300, which would feel normal. The problem is that without position sensitive damping, the amount of rebound damping required to keep the rear end in check during the main 6" of travel would be too much for the 81.125lb rate to overcome, and it would droop out too slowly to be effective.

Foes is running an airshock which cant be set-up as a dual rate, only more or less linear by using volume, and in order to get it light enough at the beginning of the stroke, it would ramp-up like mad at the end, and that's no bueno.


I don't know why people assume his set-up wouldn't be bunny-hoppable. From the normal riding position it would handle like any other DH frame, once airborne the wheel would sit a bit lower than a normal bike, but it's such a light rate that it would move up fairly easily if you tagged a rock with it.

 

[Wetbed0]

Two springs in line act simultaneously. They'll act with the rate 1/k=1/k1+1/k2. Put two 500lb/in springs in line, and you end up with 250 lb/in.
Putting a light spring on the small shock would lower the total spring rate throughout the entire travel.
They'd have to be isolated from each other in some way. I figure special windings would react the same, just with the spring rate increasing as the low rate coils bottoming out on one another. Giving you a more expensive, harder to tune, falling leverage rate. At least, that's how it works out to me. He can really only rely on damping to slow down the droop compression, and slowly compress the main shock. Giving 12" of sprung upwards travel but only 9" of sprung downward travel. So the wheel shouldn't rebound into holes like normal sag, it should drop slow like how the wheel falls with thes spring removed, but you'll have contact sooner apon reaching the other side of the hole.

Maybe I'll make an animation, this sounds better than when I first read it.

 

[Wetbed0]

Cool, Mobile let you beat me to it.

 

[dcamp29]

Seems like when the rear wheel is in contact with the ground- due to the travel of the 2nd shock- there won't be much weight/force pressing it onto the ground because of the super light 2nd springrate, therefore not much traction gained... sure the wheel is touching the ground, but no weight on it=no traction


Not to mention they are using a turd CCDB air shock as the primary

 

[IH8Rice]

Not to mention they are using a turd CCDB air shock as the primary

totally. cane creek makes crap right?

 

[dan-o]

because of reality.

This is the internet so that **** doesn't apply here.

 

[goodgrief]

What happens when you dive into a steep chute on the brakes and the weight shift causes the little shock to extend? Doesn't sound like a desirable situation to me.

 

[Wetbed0]

What happens when you dive into a steep chute on the brakes and the weight shift causes the little shock to extend? Doesn't sound like a desirable situation to me.

It most likely won't. The little shock would only extend if the rear wheel left the ground, even then, it won't take much to compress it.

 

[Vrock]

Seems like when the rear wheel is in contact with the ground- due to the travel of the 2nd shock- there won't be much weight/force pressing it onto the ground because of the super light 2nd springrate, therefore not much traction gained... sure the wheel is touching the ground, but no weight on it=no traction

That's why he said that he is goint to experiment with diferent springs rates and different damping ratios. Let's say it's a 50lbs coil, no rebound at all and a bit of compresion, that can put some weight on the tire. The coil can have a ton of Preload too, maybe he can set it up so it's the fastest damper to react when the tire leaves the ground...

 

[dcamp29]

totally. cane creek makes crap right?

you ridden a CCDB air back to back with a CCDB coil? I have.

Their damper is great; the air spring is garbage.

 

[dcamp29]

That's why he said that he is goint to experiment with diferent springs rates and different damping ratios. Let's say it's a 50lbs coil, no rebound at all and a bit of compresion, that can put some weight on the tire. The coil can have a ton of Preload too, maybe he can set it up so it's the fastest damper to react when the tire leaves the ground...

Fair enough- i didn't listen to audio, and just saw how easy it was to pull the wheel up in the video.

 

[Wetbed0]

Other end of the spectrum, will we have to revalve for a change in unsprung weight? That could get old.

 

[WestCoastHucker]

removing a shock bolt would have been a cheaper option...

 

[maxyedor]

Fair enough- i didn't listen to audio, and just saw how easy it was to pull the wheel up in the video.

Remember though, at that point on a traditional design, your wheel is already off the ground. You're trading a wheel in the air for a wheel on the ground with minimal ground pressure.

 

[dcamp29]

maybe. Is that weak 2nd springrate strong enough to quickly push the wheel back in contact with the ground?

or did it just take away 3" of your bunnyhop? now you can't jump as much stuff as you once could... Good or bad? more testing needs to be done.

 

[Wetbed0]

Who's going to try it at inter bike?

 

[OGRipper]

maybe. Is that weak 2nd springrate strong enough to quickly push the wheel back in contact with the ground?

or did it just take away 3" of your bunnyhop? now you can't jump as much stuff as you once could... Good or bad? more testing needs to be done.

I had similar questions for a guy at the Foes booth at Sea Otter, but there wasn't really an answer. Even Brent admits in that video that they don't really know how it's going to work.

Not sure why they even showed it with so many unanswered questions, but I guess they needed to give people a reason to talk about Foes. Any publicity is good, right? Right?

 

[maxyedor]

maybe. Is that weak 2nd springrate strong enough to quickly push the wheel back in contact with the ground?

or did it just take away 3" of your bunnyhop? now you can't jump as much stuff as you once could... Good or bad? more testing needs to be done.

The spring will rebound almost instantly no matter the spring-rate as as the coil has virtually no damping, an air-spring has only stiction damping it, the exception is an elastomer which has it's own, unalterable, damping. The way it appears the Foes works is that there's an ultra light rate combined with ultra minimal damping to allow it to instantly droop-out when un-weighted and instantly compress when weighted. In stutter bumps the 3" of "bonus" travel could become active mid-stroke as the rear will usually come off the ground and back onto it so quickly that the main shock won't allow the rear tire to droop out fast enough, the secondary shock would allow it to drop into the hole.

Yes, you'd lose 3" of your bunny-hop, but in practice, not sure if that makes a difference as the rate would be light enough to just bump the tire up out of the way if it tagged a log or rock.

Not sure why they even showed it with so many unanswered questions, but I guess they needed to give people a reason to talk about Foes. Any publicity is good, right? Right?

I think it's actually pretty cool that they showed up with a concept in the infant stages. We never get to see anything new from bike companies until it's 99% production ready. All bike companies are trying new stuff, they just don't publicize it anymore since people freak out at the sight of an abnormal bike, and assume a failed concept means the company's engineers suck at life. Think about all the nutty stuff they tried back in the 90s, most of it didn't work, but if they hadn't tried everything they could think of, none of the stuff that actually did find it's way into production would have come about.

 

[Jm_]

All bike companies are trying new stuff, they just don't publicize it anymore since people freak out at the sight of an abnormal bike, and assume a failed concept means the company's engineers suck at life. Think about all the nutty stuff they tried back in the 90s, most of it didn't work, but if they hadn't tried everything they could think of, none of the stuff that actually did find it's way into production would have come about.

The reason you probably don't see this stuff is that it's nutty and it probably doesn't work.

 

[HardtailHack]

The way it appears the Foes works is that there's an ultra light rate combined with ultra minimal damping to allow it to instantly droop-out when un-weighted and instantly compress when weighted. In stutter bumps the 3" of "bonus" travel could become active mid-stroke as the rear will usually come off the ground and back onto it so quickly that the main shock won't allow the rear tire to droop out fast enough, the secondary shock would allow it to drop into the hole.

Ahhh yes good point there if it was setup quick enough that could work, however if it did happen feeling that secondary shock bottom out when you are mid stoke on the main shock could be weird.

After setting up my fork with about 30mm of neg travel I can run quite a bit less rebound damping without feeling like the bike will buck me.

 

[dcamp29]

The spring will rebound almost instantly no matter the spring-rate as as the coil has virtually no damping, an air-spring has only stiction damping it, the exception is an elastomer which has it's own, unalterable, damping. The way it appears the Foes works is that there's an ultra light rate combined with ultra minimal damping to allow it to instantly droop-out when un-weighted and instantly compress when weighted. In stutter bumps the 3" of "bonus" travel could become active mid-stroke as the rear will usually come off the ground and back onto it so quickly that the main shock won't allow the rear tire to droop out fast enough, the secondary shock would allow it to drop into the hole.

Yes, you'd lose 3" of your bunny-hop, but in practice, not sure if that makes a difference as the rate would be light enough to just bump the tire up out of the way if it tagged a log or rock.

I'm not so sure- your swingarm and rear wheel have substantial weight 10+ lbs... is that weak spring rate enough to quickly change the direction of that heavy swingarm assembly? If a 500lb spring can't keep the wheel on the ground, how exactly is a lesser spring going to do that? No damping? Pro's run fast rebound settings anyways.


I wish foes had just made that bike without the 2nd shock- they could probably sell some.

 

[WestCoastHucker]

...I wish foes had just made that bike without the 2nd shock- they could probably sell some.

i'm sure that was/is their intention all along. they just wanted to generate some hype ahead of time...

 

[Bikael Molton]

Does Foes sell frames though?

 

[troy]

it is like having 3 inches of play in the rear.

So it's like riding a bike made by Intense?

 

[IH8Rice]

you ridden a CCDB air back to back with a CCDB coil? I have.

Their damper is great; the air spring is garbage.

yup. for about a month. ive had the air on my dh bike for the past two years

 

[dcamp29]

yup. for about a month. ive had the air on my dh bike for the past two years

what bike and shock configuration (length x stroke)? I tested on a Trek Session 8.75x2.75.

you're on coil now? what do you think?

I loved the DB coil, hated the air. Obviously both were quality, well made pieces, but the air spring was SUPER wallowy. We tried all combos of volume spacers etc. Nothing worked, I'd rather have an extra 5 lbs on the bike than run that air spring.


That is why I question any DH rig with CCDB air.

 

[blindboxx2334]

has anyone else had no luck with a ccdba? i think youre the first person ive heard/read that didnt like the air..

 

[jackalope]

I have one on my trail bike and I'm still a terrible rider, so maybe the air spring is crap.

My lack of offroad cycling prowess aside, my ccdba has certainly been a revolutionary upgrade compared to the OEM Fox Float CTD, but I've never tried one out on a DH bike. I know several guys run them on V10s and I'm sure on other bikes as well, and it seems like they've worked well in those applications. I'm not familiar with the leverage curve of the Session, but perhaps it needs the larger volume can if it's pretty progressive - although I'm not sure if or how that would really address the dreaded "mid-stroke wallow", as it would seem you need moar progressivity rather than less.

 

[jonKranked]

what bike and shock configuration (length x stroke)? I tested on a Trek Session 8.75x2.75.

you're on coil now? what do you think?

I loved the DB coil, hated the air. Obviously both were quality, well made pieces, but the air spring was SUPER wallowy. We tried all combos of volume spacers etc. Nothing worked, I'd rather have an extra 5 lbs on the bike than run that air spring.


That is why I question any DH rig with CCDB air.

which canister were you using?

 

[dcamp29]

Not sure about the canister- it was definitely a large volume 'outer canister' IE the air piston rode on another layer inside this can. we played with volume reducers for quite a while and never got anywhere good. one issue is a lack of negative air volume- we took it apart and there is almost no volume for negative spring volume. I think part of the issue is the 8.75x2.75 shock is one of the smallest/tightest packaging wise, and maybe canecreek ran out of room for negative volume on that one configuration.


It felt like the neg spring was only effective for the first 10% of travel or so. then you just get 60% travel is used by wallow, then she ramps up hard. so you'd end up skipping around topped out (relatively), then hit some medium bumps and use way too much travel. The difference was just soo big compared to a plain old coil. Could be session's leverage rate? I don't know- the session seems to have a fairly average leverage rate.

 

[dcamp29]

has anyone else had no luck with a ccdba? i think youre the first person ive heard/read that didnt like the air..

yeah me too- everyone else seems to love them, but I had a bad experience with them. That is why I'm wary of people spec'ing or buying the air shocks... That said, I'd run the coil no problem.

 

[tacubaya]

Weird. I run a 8.75x2.75 CCDBA on a Canfield The One (XV air sleeve with 1 big volume spacer and 2 small ones) with no issues..

 

[dcamp29]

Weird. I run a 8.75x2.75 CCDBA on a Canfield The One (XV air sleeve with 1 big volume spacer and 2 small ones) with no issues..

is that the only shock you've ever had on that bike?

 

[tacubaya]

is that the only shock you've ever had on that bike?

No, I ran an X-Fusion HLR Coil and a HLR Air on it previously.

 

[Muddy]

When and if any pedaling has a need, how is this setup not going to spike the shock used for the normal function on the suspension??

This has got to be a rough draft - the concept only applies to the segment of bikes which have a somewhat perpendicular shock arrangement.