No, it just may feel like it because most bikes slow down so significantly when going through a rock garden, when hopping on something like a Lahar or a BMW with all very rearward travel, you slow down a lot less.This has been confusing me all night...
Is it actually possible that a bike can speed up over a hit due to chain growth and pedal kickback (so long as there is a rider on there and they keep their pedals in the same positions)?
The difference is a heck of a lot less than you might think. People seem to think that somehow a super high single pivot is some sort of magical thing that is going to help your suspension absorb bumps some incredible amount better. It's just not true. When you actually calculate forces in the suspension, most current suspensions are so close to each other that the difference is less than a couple percent. Most riders forget that the wheel is part of your suspension system. Your wheel is in essence a big lever that manipulates your swingarm. The wheel acts somewhat like a cam, and the action of your wheel levering your suspension over a bump really makes the reality of how suspensions absorb bumps a lot different than most riders envision suspensions functioning. Leverage rate, shock setup, and anti-squat all have huge impacts on suspension performance as compared to how rearward or not your axle path is.No, it just may feel like it because most bikes slow down so significantly when going through a rock garden, when hopping on something like a Lahar or a BMW with all very rearward travel, you slow down a lot less.
Sure, as long as your freewheel is not overrunning, which is commonly the case (like 99.9% of the time) when you are on a descent.This has been confusing me all night...
Is it actually possible that a bike can speed up over a hit due to chain growth and pedal kickback (so long as there is a rider on there and they keep their pedals in the same positions)?
it might not be a big difference on paper, but it is certainly tangible on the bike, yes. pretty neat, the relative 'lack of hanging up' does feel like acceleration through the big square edged hooky stuff.No, it just may feel like it because most bikes slow down so significantly when going through a rock garden, when hopping on something like a Lahar or a BMW with all very rearward travel, you slow down a lot less.
I've spent a lot of time years ago comparing a BB7 vs an FSR bike, timed, with data aquisition, and regardless of what you "think" you are feeling, the difference is negligible.it might not be a big difference on paper, but it is certainly tangible on the bike, yes. pretty neat, the relative 'lack of hanging up' does feel like acceleration through the big square edged hooky stuff.
Still if you feel the bike rides faster and it makes you more comfortable/confident with the bike the placebo may make you go fasterdw, that mention of the rear wheel being both a lever and a cam is helpful for me to understand suspension dynamics. thanks for that. and thanks also for stating the point that perception often doesn't match reality, that's a point I try to make with people in many subjects of discussion. people often perceive what they want to perceive. this is why pharma tests run placebos.
true. seat of the pants 'faster' does not always equate to significant time savings. just a perceptual observation for what it's worth. if you've got good geometry & properly tuned dampers, suspension platform probably doesn't make a huge difference (though it's amusing to squabble about); the guy on the bike is obviously the biggest factor.I've spent a lot of time years ago comparing a BB7 vs an FSR bike, timed, with data aquisition, and regardless of what you "think" you are feeling, the difference is negligible.
Just like people feel like they are faster on a 500CC 2 stroke MX bike, then compare their times to their 125 and find out they lapped slower on the big bike. In many, MANY cases, perception is not reality. This is why we have stopwatches and data acquisition to analyze suspension.
Hmm ineresting, how was this data aquistion carried out?I've spent a lot of time years ago comparing a BB7 vs an FSR bike, timed, with data aquisition, and regardless of what you "think" you are feeling, the difference is negligible.
Just like people feel like they are faster on a 500CC 2 stroke MX bike, then compare their times to their 125 and find out they lapped slower on the big bike. In many, MANY cases, perception is not reality. This is why we have stopwatches and data acquisition to analyze suspension.
Wow, I am flabbergasted because up til now, i always thought my BB7 "felt" faster in rock gardens compared to my Glory.I've spent a lot of time years ago comparing a BB7 vs an FSR bike, timed, with data aquisition, and regardless of what you "think" you are feeling, the difference is negligible.
It does "feel" faster. If post-enlightenment European philosophy has taught us anything it is that perception and reality can at times be disconnected. The proprioceptive responses of our central nervous system are highly advanced, but not in any sort of way that reliably notices changes in velocity.Wow, I am flabbergasted because up til now, i always thought my BB7 "felt" faster in rock gardens compared to my Glory.
Favorite post in days.It does "feel" faster. If post-enlightenment European philosophy has taught us anything it is that perception and reality can at times be disconnected. The proprioceptive responses of our central nervous system are highly advanced, but not in any sort of way that reliably notices changes in velocity.
yeah, for sure! that's more important in the long run for getting faster -- being confident, being comfortable. I'd eat any placebo that helped me relax and feel more confident when things get hairy!Still if you feel the bike rides faster and it makes you more comfortable/confident with the bike the placebo may make you go faster
I try not to eat anything too hairyyeah, for sure! that's more important in the long run for getting faster -- being confident, being comfortable. I'd eat any placebo that helped me relax and feel more confident when things get hairy!
I don't think a super high pivot does much, but an axle path that is lightly rearward vectored for most of it's path (lapierre dh920) will have more ease at transfering the potential energy of the bike+rider to the shock than to the bump. It may not be much, but it is definitly noticeble to me in both feel (which is by far the most important to me) as well as speed.The difference is a heck of a lot less than you might think. People seem to think that somehow a super high single pivot is some sort of magical thing that is going to help your suspension absorb bumps some incredible amount better. It's just not true. When you actually calculate forces in the suspension, most current suspensions are so close to each other that the difference is less than a couple percent. Most riders forget that the wheel is part of your suspension system. Your wheel is in essence a big lever that manipulates your swingarm. The wheel acts somewhat like a cam, and the action of your wheel levering your suspension over a bump really makes the reality of how suspensions absorb bumps a lot different than most riders envision suspensions functioning. Leverage rate, shock setup, and anti-squat all have huge impacts on suspension performance as compared to how rearward or not your axle path is.
dilzy, one of the things I think of when I read that statement is, "isn't he really saying that he's faster on the Cove?"I've ridden a Demo 9 that has quite a forward path past sag and my cove is definitely faster over a long downhill rock garden one one of our regular runs.
Yeah I see what your saying, It's a bit of a dodge test, but I remember following a mate on that demo going down at the same speed not pedalling and I caught right up to him by the end. He said he didn't use any brakes.dilzy, one of the things I think of when I read that statement is, "isn't he really saying that he's faster on the Cove?"
I don't see how the bike is faster, I don't know how it can be, unless you can let the Demo and Cove ghost-ride from the same start position and same start speed.
am I making sense? I'm saying it sounds like you are more comfortable in the rocks on the Cove, and that means you're faster in the rocks on the Cove.
to get some proper results from a test like this you would need identical bike builds ( so weight and suspension performance would be the same. the same distance between ground and handlebars, ground vs pedals so that the weight distribution is the same ) geometry, tire pressures , suspension set up, riders (same weight, riding style, skill level). they would have to be riding exactly the same line, and even than differences in weight shifts/distributions over obstacles or in the corners would mess it up... all in all... nearly impossible.Yeah I see what your saying, It's a bit of a dodge test, but I remember following a mate on that demo going down at the same speed not pedalling and I caught right up to him by the end. He said he didn't use any brakes.
I disagree, the vestibular apparatus of the inner ear allow us to balance by accurately measuring changes in the direction of the acceleration due to gravity. In addition, any change in velocity is an acceleration which results in forces tangible to the entire body. While I concede that a person's sense of time is not accurate enough to judge the speed of an entire race run, it is possible that for small sections of terrain a rider may accurately deduce, if given a direct comparison, the faster of two velocipedes.It does "feel" faster. If post-enlightenment European philosophy has taught us anything it is that perception and reality can at times be disconnected. The proprioceptive responses of our central nervous system are highly advanced, but not in any sort of way that reliably notices changes in velocity.
you use your mouth prettier than a $20 whoreI disagree, the vestibular apparatus of the inner ear allow us to balance by accurately measuring changes in the direction of the acceleration due to gravity. In addition, any change in velocity is an acceleration which results in forces tangible to the entire body. While I concede that a person's sense of time is not accurate enough to judge the speed of an entire race run, it is possible that for small sections of terrain a rider may accurately deduce, if given a direct comparison, the faster of two velocipedes.
I realise you've done the DAQ work and that, and to some degree and in some cases I agree with what you're saying - but particularly as angles of incidence get higher (ie larger square bumps) the difference becomes more pronounced (from my empirical experience, not actual measurements). The wheel acts as another bar of the suspension, yes, but any force components that are perpendicular to the direction of the bike's movement (ie horizontal) will act to decelerate the bike, which is that hanging up sensation you get. If the horizontal impulse is reduced (by having the wheel able to decelerate in the horizontal axis without taking the whole bike with it) then it is irrefutable that the bike will slow down less. As the bump gets closer and closer to the critical angle, the difference becomes more and more pronounced. If I get time I'll draw up a simulation of it - theoretical I know, but I honestly believe there is merit to fairly rearwards axle paths (wheel rate etc all being equal) in terms of straight-line bump absorption.Just to make sure that my point isn't taken out of context, let me reiterate the important parts.
There are other factors in a suspension design (wheel diameter, wheel rate/ leverage rate, shock setup) that have a much larger effect on a suspension's ability to absorb bumps than the rearwardness of your suspension travel. You could have the most rearward axle path in the world, but if your suspension isn't engineered to work properly with your damper, then it's not going to matter. This doesn't even get into the fact that too rearward of an axle path is detrimental to cornering. I've written a lot about this in detail in the past on this board, I'm sure someone could dig it up if they were interested.
I think that we are making the same point. I'm not saying that rearwardness of axle path is completely insignificant, I'm just stating that mathematics and data acquisition show that other suspension factors are incredibly more significant when it comes strictly to effectively absorbing bumps.I realise you've done the DAQ work and that, and to some degree and in some cases I agree with what you're saying - but particularly as angles of incidence get higher (ie larger square bumps) the difference becomes more pronounced (from my empirical experience, not actual measurements). The wheel acts as another bar of the suspension, yes, but any force components that are perpendicular to the direction of the bike's movement (ie horizontal) will act to decelerate the bike, which is that hanging up sensation you get. If the horizontal impulse is reduced (by having the wheel able to decelerate in the horizontal axis without taking the whole bike with it) then it is irrefutable that the bike will slow down less. As the bump gets closer and closer to the critical angle, the difference becomes more and more pronounced. If I get time I'll draw up a simulation of it - theoretical I know, but I honestly believe there is merit to fairly rearwards axle paths (wheel rate etc all being equal) in terms of straight-line bump absorption.
Isn't there also a factor of having the wheel "push" down the backside of bumps? In which case a suspension design with initial rearward AP to forward is actually faster with a good rider on there?The difference is a heck of a lot less than you might think. People seem to think that somehow a super high single pivot is some sort of magical thing that is going to help your suspension absorb bumps some incredible amount better. It's just not true. When you actually calculate forces in the suspension, most current suspensions are so close to each other that the difference is less than a couple percent. Most riders forget that the wheel is part of your suspension system. Your wheel is in essence a big lever that manipulates your swingarm. The wheel acts somewhat like a cam, and the action of your wheel levering your suspension over a bump really makes the reality of how suspensions absorb bumps a lot different than most riders envision suspensions functioning. Leverage rate, shock setup, and anti-squat all have huge impacts on suspension performance as compared to how rearward or not your axle path is.
That's one bump. How does it all change when hitting multiple bumps really fast?I realise you've done the DAQ work and that, and to some degree and in some cases I agree with what you're saying - but particularly as angles of incidence get higher (ie larger square bumps) the difference becomes more pronounced (from my empirical experience, not actual measurements). The wheel acts as another bar of the suspension, yes, but any force components that are perpendicular to the direction of the bike's movement (ie horizontal) will act to decelerate the bike, which is that hanging up sensation you get. If the horizontal impulse is reduced (by having the wheel able to decelerate in the horizontal axis without taking the whole bike with it) then it is irrefutable that the bike will slow down less. As the bump gets closer and closer to the critical angle, the difference becomes more and more pronounced. If I get time I'll draw up a simulation of it - theoretical I know, but I honestly believe there is merit to fairly rearwards axle paths (wheel rate etc all being equal) in terms of straight-line bump absorption.
That's where your shock setup has vastly more effect. The extra forward momentum of a wheel swinging back into place on a high-pivot would be nearly immeasurable.That's one bump. How does it all change when hitting multiple bumps really fast?
unfortunately, most of it has been lost in very old threads which have been deleted. i have tried finding them many times before with no luck.I've written a lot about this in detail in the past on this board, I'm sure someone could dig it up if they were interested.