Doesn’t seem very heavy when that’s the curb weight of a Ford Raptor, and I usually see those used for grocery shopping instead of the Baja...
Doesn’t seem very heavy when that’s the curb weight of a Ford Raptor, and I usually see those used for grocery shopping instead of the Baja 1000
Plus a Raptor would get its ass handed to it if you tried to drive similar terrain at anywhere near the same speed. They can do more than most people realize a factory vehicle can do, but they are about as close to a trophy truck as a cross country bike is to a DH bike.
the shock didn't have external tubes, though did it? they were the first thing i thought of when looking at these shocks : ) the 2:1 Foes Curnutt frame (whether it was good or not) was such a drool machine for me!
I was told that one year Foes had a bypass shock with a carbon fiber leaf as the spring. Not sure what year. Back in the day Foes was a part of the Nissan Factor team.
Plus a Raptor would get its ass handed to it if you tried to drive similar terrain at anywhere near the same speed. They can do...
Plus a Raptor would get its ass handed to it if you tried to drive similar terrain at anywhere near the same speed. They can do more than most people realize a factory vehicle can do, but they are about as close to a trophy truck as a cross country bike is to a DH bike.
Cascade has nailed it. As someone who has a Spec truck I feel like he has some really good info. My brand new spec truck is 5300 lb with a 92 gal fuel cell and 525 hp. The speeds we hit things at are crazy. I always say its like throwing a hammer through the desert. The frame of a raptor is not designed to take the big hits.
The reason the trucks are so heavy is that they are designed to take an insane amount of abuse. Plus the weight helps the truck settle into the holes instead of just bouncing off of them. My new truck is considered on the light side Watch a video of a class 10, they are light and just bounce around compared to a truck. Its the same reason a lot of pros are adding weight to their bikes.
the shock didn't have external tubes, though did it? they were the first thing i thought of when looking at these shocks : ) the 2:1...
the shock didn't have external tubes, though did it? they were the first thing i thought of when looking at these shocks : ) the 2:1 Foes Curnutt frame (whether it was good or not) was such a drool machine for me!
Not familiar with the internals of that Foes shock, but internal bypasses are common and have the same end goal minus adjustability. But generally anyone who's hitting things hard runs a coilover plus external bypass at each corner so I don't think there really are internal bypasses with the same level of capability. This is how Fox does internal bypasses:
Cascade has nailed it. As someone who has a Spec truck I feel like he has some really good info. My brand new spec truck is...
Cascade has nailed it. As someone who has a Spec truck I feel like he has some really good info. My brand new spec truck is 5300 lb with a 92 gal fuel cell and 525 hp. The speeds we hit things at are crazy. I always say its like throwing a hammer through the desert. The frame of a raptor is not designed to take the big hits.
The reason the trucks are so heavy is that they are designed to take an insane amount of abuse. Plus the weight helps the truck settle into the holes instead of just bouncing off of them. My new truck is considered on the light side Watch a video of a class 10, they are light and just bounce around compared to a truck. Its the same reason a lot of pros are adding weight to their bikes.
This is why I'm always surprised when people want to throw loads of power at their Raptor. You can easily overwhelm the suspension on them with 450 hp. Then with a tune you can hit spec truck power levels. And of course the R has more than a spec truck bone stock.
This is why I'm always surprised when people want to throw loads of power at their Raptor. You can easily overwhelm the suspension on them with...
This is why I'm always surprised when people want to throw loads of power at their Raptor. You can easily overwhelm the suspension on them with 450 hp. Then with a tune you can hit spec truck power levels. And of course the R has more than a spec truck bone stock.
I don't know about the F150 Raptor, but Jason Cammisa smoked the brakes to near failure on the Bronco Raptor during his review on the street.
It's easy to increase power on modern turbo engines with a tune, but that doesn't make the rest of the car/ truck more capable.
The saying still holds true " you can always add more power, but you can only have too little brakes once".
Obviously, I know what a hydraulic inerter is... But maybe you could explain it to sspomer here and I'll review?On the more serious note, is the...
Obviously, I know what a hydraulic inerter is... But maybe you could explain it to sspomer here and I'll review?
On the more serious note, is the RS touchdown tech purely for feel? I can't imagine unweighted bike damping bypass plays much of a role in suspension performance.
So the really neat thing about the spring-mass-damper system is that it is relatively analogous to an electrical circuit, known as the Mobility Analogy. The classical thinking is that mass acts as capacitance, dampers act as a resistor, and the spring and compliance acts as an inductor. And with those, velocity becomes the voltage and the current is the force. Some define these differently, but for the inerter problem this makes the most sense. So the problem with this thinking though is that mass actually doesn't exactly translate as an ungrounded capacitor. So Malcolm Smith in 2002 came up in defining what would be the mechanical equivalent of an ungrounded capacitor and that was what he ended up calling, an inerter. What this all means is that an inerter can produce "inertance" aka inertia but without the negatives of all the actual physical weight, now Smith might disagree with using that analogy but alas. So a small amount of mass can act many times it's effective mass under accelerations. The original inerters were gears or screws that spun up balls or flywheels to absorb excess energy as a spring-damper system had force applied against it, then as the force came off the system these flywheels would put the energy back into spring-damper driving it back down towards reaching equilibrium. Now-a-days inerters are done with the same hydraulic fluid that operates the damper.
With this system, a damper still provides "resistance" towards velocity while the inerter provides inertia towards accelerations. So at constant velocity the inerter should provide 0 kgf/lbf of inertia but as velocity changes, aka acceleration, it provides a force back. A lot of the benefits of the inerter are pretty similar to a mass damper, but there are two main items an inerter does much better. 1) A relatively small mass can act as a much larger mass. In the case of a hydraulic inerter you are talking about a very small mass increase (on a bike we're probably talking about a pound or less once the tech was mature, imho) resulting in potentially 100s of pounds of inertial force. 2) The acceleration sensitivity is the other key, mass dampers get tuned at a certain frequency and while they affect other frequencies, they are still a very targeted device. Whereas the inerter allows you to really act at all frequencies. So these things result in reduced tire contact patch load variation, reduced chassis movement, and less vibration returning to the meatbag controlling the vehicle. Though of course how much it affects each of these elements is a tradeoff and in a downforce heavy racecar, reducing body movement is the real winner. This is why when F1 changed rules a few years ago, cars started wildly osculating vertically. Most put the blame on the revised underwing rules, but few thought about the fact that they had lost the ability to run inerters...
So in the mountain bike world, it would be very interesting to implement this. Ohlins for sure has hydraulic inerter capabilities in house as they have IndyCar dampers with this. Would certainly be interesting to see if it's made it's way onto those Specialized Gravity bikes ever. But maybe there's packaging issues or something else I'm not smart enough to be aware of that isn't conducive to that...I would certainly spend my time and effort on adding an inerter over a tuned mass damper though. Far more tunable, far quicker to tune, and adds less weight to the bike.
Also while I have a soapbox, at some point bike companies need to stop being endlessly fascinated with just talking about kinematics and changes to them and actually get really serious about modeling their "vehicle" and what actually matters towards riding faster. Kinematics is just a gross simplification of trying to understand the dynamic forces and moments acting on the system that result in chassis ride height changes and the load on the tires which go back to producing forces and moments that cycle back around again ad-nauseum. i.e., if you are adding mass to a bike to go faster, what are you band aiding...
the shock didn't have external tubes, though did it? they were the first thing i thought of when looking at these shocks : ) the 2:1...
the shock didn't have external tubes, though did it? they were the first thing i thought of when looking at these shocks : ) the 2:1 Foes Curnutt frame (whether it was good or not) was such a drool machine for me!
Not familiar with the internals of that Foes shock, but internal bypasses are common and have the same end goal minus adjustability. But generally anyone who's...
Not familiar with the internals of that Foes shock, but internal bypasses are common and have the same end goal minus adjustability. But generally anyone who's hitting things hard runs a coilover plus external bypass at each corner so I don't think there really are internal bypasses with the same level of capability. This is how Fox does internal bypasses:
King does them like this:
Robby Gordon used to make large internal bypass shocks. He ran them on all his trucks. The main problem with them was oil capacity. In races like san Felipe they would over heat. This is one of the main advantages of 2 shock per wheel, more oil. Then when you make your bypass shock bodies 4.5", you can hold a lot of oil in them keep them cool. Another problem is they don't make coils big enough to go around a 4.5" body with tube's. Only know of 3" coils.
Yes. Have you seen what they drive through? Marzocchi had a super basic (like really basic) bypass compression circuit in the 888 from 2004, with progressively smaller...
Yes. Have you seen what they drive through?
Marzocchi had a super basic (like really basic) bypass compression circuit in the 888 from 2004, with progressively smaller holes drilled in the side of the tube and the Vorsprung Smashpot is a much more advanced version of that, both acting as HBO circuits.
DT swiss and some specialized brain forks had a touchdown-esque design that deactivated damping in the very top part of the stroke too
The Manitou TPC+ design is/was kind of speed + position sensitive - a second piston could float up and down until a large enough impact caused it to hit an end stop so oil was forced through it, and you could adjust how much float it had before it hit the stop.
I almost died in maybe the biggest crash of my life the first day I rode one of those 888's! I came through a fast piece...
I almost died in maybe the biggest crash of my life the first day I rode one of those 888's! I came through a fast piece of track that dropped out in to a rutted 4wd track so much faster than I used to with my old Manitou that I was in no way ready for it 😅 Another nugget about that fork which I found funny is that Dirt ran a comparison between those, the (brand new) Fox 40, manitou Dorado and Rockshox Boxxer and declared it the winner even though the other forks were light years ahead technology wise. It just showed how good an open bath coil sprung fork with decent stanchions was, due to its low friction and the rest of the features arent that important (this holds true today by the way!)
Yes this! A friction-less well aligned system is absolutely more important then all the other items they fuss about today. That is a big part of the reason coils feel so good. Also open bath system are so underrated now a days.
the shock didn't have external tubes, though did it? they were the first thing i thought of when looking at these shocks : ) the 2:1...
the shock didn't have external tubes, though did it? they were the first thing i thought of when looking at these shocks : ) the 2:1 Foes Curnutt frame (whether it was good or not) was such a drool machine for me!
I hadn't seen a Foes with a bypass shock but their history page does refer to an early leaf sprung bike with a sway-a-way damper which might be what it refers to. Couldn't see more info but they took a lot of inspiration from racing trucks so it wouldn't surprise me
Those 2:1 bikes were one of my favourite bikes just for how wild they were, especially the 5 inch stroke shock with a dual rate spring! The one in the picture is so crazy it took a few looks before I noticed the small block eight xc tyres 😅
the shock didn't have external tubes, though did it? they were the first thing i thought of when looking at these shocks : ) the 2:1...
the shock didn't have external tubes, though did it? they were the first thing i thought of when looking at these shocks : ) the 2:1 Foes Curnutt frame (whether it was good or not) was such a drool machine for me!
The Curnutt shock had multiple grooves of different length on the inside of the damper tube. This worked very much like an external bypass. The grooves in the shock body allowed some of the damping fluid to "bypass" the main piston. As the shock moved deeper into it's travel it would pass the shorter grooves pushing more and more fluid through the piston and allowing less to bypass. Eventually there were no grooves and all the oil was going through the piston. I tried for about an hour to find a picture (I remember one from back in the day), but can't find it on the web.
The latest incarnation looks to use a different mechanism.
Plus a Raptor would get its ass handed to it if you tried to drive similar terrain at anywhere near the same speed. They can do more than most people realize a factory vehicle can do, but they are about as close to a trophy truck as a cross country bike is to a DH bike.
Some guy at Dakar after a few beers " why don't we just race the support trucks too?"
Some guy working for Unimog "we can make that happen"
Interesting thread! Thanks for sharing
Foes Curnutt shock had this technology on mountain bikes over 20 years ago.
the shock didn't have external tubes, though did it? they were the first thing i thought of when looking at these shocks : ) the 2:1 Foes Curnutt frame (whether it was good or not) was such a drool machine for me!
(Not mine)
https://www.vitalmtb.com/community/_,57806/setup,46320
I was told that one year Foes had a bypass shock with a carbon fiber leaf as the spring. Not sure what year. Back in the day Foes was a part of the Nissan Factor team.
Cascade has nailed it. As someone who has a Spec truck I feel like he has some really good info. My brand new spec truck is 5300 lb with a 92 gal fuel cell and 525 hp. The speeds we hit things at are crazy. I always say its like throwing a hammer through the desert. The frame of a raptor is not designed to take the big hits.
The reason the trucks are so heavy is that they are designed to take an insane amount of abuse. Plus the weight helps the truck settle into the holes instead of just bouncing off of them. My new truck is considered on the light side Watch a video of a class 10, they are light and just bounce around compared to a truck. Its the same reason a lot of pros are adding weight to their bikes.
Not familiar with the internals of that Foes shock, but internal bypasses are common and have the same end goal minus adjustability. But generally anyone who's hitting things hard runs a coilover plus external bypass at each corner so I don't think there really are internal bypasses with the same level of capability. This is how Fox does internal bypasses:
King does them like this:
This is why I'm always surprised when people want to throw loads of power at their Raptor. You can easily overwhelm the suspension on them with 450 hp. Then with a tune you can hit spec truck power levels. And of course the R has more than a spec truck bone stock.
I don't know about the F150 Raptor, but Jason Cammisa smoked the brakes to near failure on the Bronco Raptor during his review on the street.
It's easy to increase power on modern turbo engines with a tune, but that doesn't make the rest of the car/ truck more capable.
The saying still holds true " you can always add more power, but you can only have too little brakes once".
So the really neat thing about the spring-mass-damper system is that it is relatively analogous to an electrical circuit, known as the Mobility Analogy. The classical thinking is that mass acts as capacitance, dampers act as a resistor, and the spring and compliance acts as an inductor. And with those, velocity becomes the voltage and the current is the force. Some define these differently, but for the inerter problem this makes the most sense. So the problem with this thinking though is that mass actually doesn't exactly translate as an ungrounded capacitor. So Malcolm Smith in 2002 came up in defining what would be the mechanical equivalent of an ungrounded capacitor and that was what he ended up calling, an inerter. What this all means is that an inerter can produce "inertance" aka inertia but without the negatives of all the actual physical weight, now Smith might disagree with using that analogy but alas. So a small amount of mass can act many times it's effective mass under accelerations. The original inerters were gears or screws that spun up balls or flywheels to absorb excess energy as a spring-damper system had force applied against it, then as the force came off the system these flywheels would put the energy back into spring-damper driving it back down towards reaching equilibrium. Now-a-days inerters are done with the same hydraulic fluid that operates the damper.
With this system, a damper still provides "resistance" towards velocity while the inerter provides inertia towards accelerations. So at constant velocity the inerter should provide 0 kgf/lbf of inertia but as velocity changes, aka acceleration, it provides a force back. A lot of the benefits of the inerter are pretty similar to a mass damper, but there are two main items an inerter does much better. 1) A relatively small mass can act as a much larger mass. In the case of a hydraulic inerter you are talking about a very small mass increase (on a bike we're probably talking about a pound or less once the tech was mature, imho) resulting in potentially 100s of pounds of inertial force. 2) The acceleration sensitivity is the other key, mass dampers get tuned at a certain frequency and while they affect other frequencies, they are still a very targeted device. Whereas the inerter allows you to really act at all frequencies. So these things result in reduced tire contact patch load variation, reduced chassis movement, and less vibration returning to the meatbag controlling the vehicle. Though of course how much it affects each of these elements is a tradeoff and in a downforce heavy racecar, reducing body movement is the real winner. This is why when F1 changed rules a few years ago, cars started wildly osculating vertically. Most put the blame on the revised underwing rules, but few thought about the fact that they had lost the ability to run inerters...
So in the mountain bike world, it would be very interesting to implement this. Ohlins for sure has hydraulic inerter capabilities in house as they have IndyCar dampers with this. Would certainly be interesting to see if it's made it's way onto those Specialized Gravity bikes ever. But maybe there's packaging issues or something else I'm not smart enough to be aware of that isn't conducive to that...I would certainly spend my time and effort on adding an inerter over a tuned mass damper though. Far more tunable, far quicker to tune, and adds less weight to the bike.
Ultimately I'm sure I've made a grave mockery of the actual science in here, so I suggest reading what you can from Malcolm Smith, such as here https://www.annualreviews.org/content/journals/10.1146/annurev-control-…;
Also while I have a soapbox, at some point bike companies need to stop being endlessly fascinated with just talking about kinematics and changes to them and actually get really serious about modeling their "vehicle" and what actually matters towards riding faster. Kinematics is just a gross simplification of trying to understand the dynamic forces and moments acting on the system that result in chassis ride height changes and the load on the tires which go back to producing forces and moments that cycle back around again ad-nauseum. i.e., if you are adding mass to a bike to go faster, what are you band aiding...
A couple years ago we had a fascinating thread on MTB inerters, including real world testing!
https://www.vitalmtb.com/forums/The-Hub,2/Mountian-bikes-and-interters,…
Robby Gordon used to make large internal bypass shocks. He ran them on all his trucks. The main problem with them was oil capacity. In races like san Felipe they would over heat. This is one of the main advantages of 2 shock per wheel, more oil. Then when you make your bypass shock bodies 4.5", you can hold a lot of oil in them keep them cool. Another problem is they don't make coils big enough to go around a 4.5" body with tube's. Only know of 3" coils.
Yes this! A friction-less well aligned system is absolutely more important then all the other items they fuss about today. That is a big part of the reason coils feel so good. Also open bath system are so underrated now a days.
I hadn't seen a Foes with a bypass shock but their history page does refer to an early leaf sprung bike with a sway-a-way damper which might be what it refers to. Couldn't see more info but they took a lot of inspiration from racing trucks so it wouldn't surprise me
Those 2:1 bikes were one of my favourite bikes just for how wild they were, especially the 5 inch stroke shock with a dual rate spring! The one in the picture is so crazy it took a few looks before I noticed the small block eight xc tyres 😅
The Curnutt shock had multiple grooves of different length on the inside of the damper tube. This worked very much like an external bypass. The grooves in the shock body allowed some of the damping fluid to "bypass" the main piston. As the shock moved deeper into it's travel it would pass the shorter grooves pushing more and more fluid through the piston and allowing less to bypass. Eventually there were no grooves and all the oil was going through the piston. I tried for about an hour to find a picture (I remember one from back in the day), but can't find it on the web.
Post a reply to: Bypass tubes on mountain bike shocks or forks? (Trophy truck tech)