Thanks to a local engineer to helped my find the linkage program - here are a few anti squat profiles showing how ventana's stack up compared to a DW link and GT Idrive. These are just a few examples for refernce purposes only.
Here's the ibis mojo...iheartbicycles said:Thanks to a local engineer to helped my find the linkage program - here are a few anti squat profiles showing how ventana's stack up compared to a DW link and GT Idrive. These are just a few examples for refernce purposes only.
Nope! But I am glad you brought that up. I think a lttle scepticism is healthy. I do not vouch for the program, but it appears to be well accepted in the community. I would be interested to hear of any faults it may have.mtnbiker4life said:Not to discount your results or data but have you researched the credibility of the linkage program? Please post this so it will add credibility to your results. :thumbsup:
http://www.ridemonkey.com/forums/showpost.php?p=3193283&postcount=393dw said:It makes me cry to see people comparing bikes with that Linkage program. As you've pointed out, unless someone measured the bike with a CMM, there is NO WAY THAT THE INFORMATION IN THE PROGRAM IS ACCURATE.
As a matter of fact, with short links like used on the Revolt, or a dw-link, a difference of 1mm makes a completely different bike. The pictures of leverage rate curves in this message are not accurate, and nobody should be basing anything off of them.
Dave
Actually if you tuned out Iheart and my discussion at the end, you missed out on some details on a killer Tahoe Ride...El Salt said:Help me understand. BTW, there is no disrespect, no baiting, no nothing hidden in this post.
Ok, now maybe some of this was addressed in the "other post" here on the Ventana board, but once things started downhill, I tuned out. I'm not interested in a war of words, or suspension design. I've ridden Ventana a long time, and haven't ridden a lot of other designs, so ignorance maybe is bliss for me. Also, for me and my riding style, I personally haven't had anything to complain about with my Ventanas. Yes, I goof around with my suspension settings, both shock and fork, when I get something new, but then I'm generally happy.
Ok, now that that is out of the way. Help me here -
Squat. Is this sag? If not, what is the difference?
Ok, so Ventanas, or the suspension designs similar to Ventana, squat(?) more than other designs in order to achieve full usage of the shock? (I'm asking, I don't know, but I think this is what I was reading on the other post.)
Ok, so this (amount of needed) squat is bad? Again, I don't know, but it seems that it is from this discussion. Its bad because? Is it bad because in order to get full usage of the rear shock I need to sag or squat so far into the stroke that I lose (effective) travel?
Ok, so for example, the suspension design of the day (and no doubt it is good, I have friends that are running it and love it), the DW, does not (need to) squat / sag as much, because of the frame design, so you are getting more usage of your over all travel? AND not "bobbing" as much, because your shock is not as soft???
Assuming that my understanding thus far is correct, does a design that "sits higher" / less squat / sag, have any issues with what I think of as "top out". I mean, does this design (i.e. DW) require additional rebound control, or is this a non-issue. Again, I don't know the answer, I'm just trying to picture the various suspensions actively cycling in my mind.
Thinking back over the past 20 years or so of mountain bike suspension styles, there have been some very interesting ones to be sure.
I always love to learn when it comes to bicycles, and suspension design is one place I need to study.
this software has security settings that don't allow this function.crisillo said:one more thing...please use "print screen" to capture the screen (or Alt + PrnScn to capture only the active application) to the clipboard and paste it as a new image in your favorite image program, that would make them easier to read
Thanks for the info
There aren't too many ventana's that have been plotted yet. THere is a 2007 Bruja showing the same antisquat as the 2005 salty. Being that pivot position is the same on the bikes (salty and bruja) and that antisquat is not a function of leverage ratio - I don't think it matters one way or the other.Ciclistagonzo said:Actually if you tuned out Iheart and my discussion at the end, you missed out on some details on a killer Tahoe Ride...
But first and foremost... No, Squat in the linkage program, is NOT Sag. Squat in this case is the force of the rider and bikes relative Center of Gravity moving backwards due to accelartion, causing the the suspension to compress ie Squat down. What I'm not sure about what the% means. But I'll assume the higher percentage number the more resistance to the "squat force" the linkage provide, what I don't know is percent of WHAT?
Another concern along the lines of what Mtbk4life is bringing up, how were the numbers for the Geometry derived? I ask because I see a nearly 10mm error in the Salty #'s for the Chainstay alone. That's a 2% error to START with. Granted if that error is carried out thru ALL the frames the relative differences stay the same.
EDIT : Not intended as critism or an attack, just trying to help in refining the numbers so they are more accurate.
EDIT II : The main pivot of the rocker is shown placed BEHIND the seattube and the head angle is a steep 71.4 degrees. Iheart did you use a pre-2005 Salty?
-A
A few points of clarification.iheartbicycles said:Thanks to a local engineer to helped my find the linkage program - here are a few anti squat profiles showing how ventana's stack up compared to a DW link and GT Idrive. These are just a few examples for refernce purposes only.
bummer..I have the older version 2 and still allows it.....iheartbicycles said:this software has security settings that don't allow this function.
That doesn't appear to be an indictiment of the program as much as the users. As the saying goes "garbage in, garbage out."Marshall Willanholly said:Here's what Dave Weagle thinks of the Linkage program:
http://www.ridemonkey.com/forums/showpost.php?p=3193283&postcount=393
I believe it's a percentage of inertia. If you know the bike is accelerating at a certain rate you can configure the initertia of the bike and it's rider. My guess is antisquat % posted is the resistance to this.Ciclistagonzo said:Actually if you tuned out Iheart and my discussion at the end, you missed out on some details on a killer Tahoe Ride...
. What I'm not sure about what the% means. But I'll assume the higher percentage number the more resistance to the "squat force" the linkage provide, what I don't know is percent of WHAT?
-A
That is what i assumed as well, but wanted to hear what others thought. I agree with your assesment about how we as rides are a dynamic being and are not a static force on our bikes. There is no 100% "efficient" design.iheartbicycles said:I believe it's a percentage of inertia. If you know the bike is accelerating at a certain rate you can configure the initertia of the bike and it's rider. My guess is antisquat % posted is the resistance to this.
The error I see in this is you can't assume 100% antisquat means the bike is 100% efficient because it doesn't take into account the rider is not a perfect machine - in addition to the downward force on the pedals, (and we all do this) we all have a tendancy to bounce a bit as we pedal. So even a bike with 100% antisquat will bob a bit. More anti squat is required to counter the effects of inertia combined with rider induced bob.
This is just my guess/understanding.
http://www.bikechecker.com/Ciclistagonzo said:That is what i assumed as well, but wanted to hear what others thought. I agree with your assesment about how we as rides are a dynamic being and are not a static force on our bikes. There is no 100% "efficient" design.
Any idea HOW anti-squat is plotted by the program? I'd like to see the equation(s)
Edit: Or a link to the program?
-A
This is simply a follow up on the many other threads where people have asked why their Ventana's squat so much while pedalling. Usually the people on the Ventana board recomend high levels of propedal and etc. This fix doesn't always work for one, and makes the suspension less active. When I brought up the idea that the suspension design itself was at fault, lacking in sufficient antisquat, it turned into an argument. So here you go.Stripes said:As a lay-reader and not a mechanical engineer..
While this is an interesting discussion, what are we supposed to take away from this?
all the designs I checked had significantly more anti squat than the ventana. The GT Idrive actually had the most. Of the Idrives, the DHI had the most (200%)Stripes said:We all need Propedal or some type of compression to offset the squat? I mean, it comes across like iheartbicycles is trying to prove something about the DW link being so much better than the Ventana designs
Ventana has never changed their anti squat profile. Being that the bike is a single pivot and that the pivots are in the same place from year to year - plotting a 2005 vs a 2009 doesn't matter. But just in case, I did go and check on a 2007 and it has the same antisquat.Stripes said:and not necessarily using current Ventana designs.
Yes, I did check one of the newer designs. The changes to the newer designs don't affect antisquat - they affect compression curves.Stripes said:Do you take into account any of the newer designs like the Bruja v2 or the Terremotto? What about running the bike with 30% sag (Sherwood recommends 30%) instead of 25% sag? Would that have an effect on the squat?
I just ride bikes, not design 'em
The program is 100% Accurate, the only problem is that pictures are not, they are always a little bit distorted, so the models are not perfect. If a bike has very small links the miskake is bigger, but it really depends on the picture that you are using to do the Linkage Model.Marshall Willanholly said:Here's what Dave Weagle thinks of the Linkage program:
http://www.ridemonkey.com/forums/showpost.php?p=3193283&postcount=393
My direct statement I thought was pretty clear. This thread is really a follow up to numerous other threads.bayareamtnbiker said:There definitely is some bob going on with my plush X5, and on long flat climbs often I crank up some propedal and even lockout the Pike. The shock and fork don't seem to get warm so I doubt any significant amount of energy is being converted to heat. I do get a lot less beat up & rattled than some of my virtual pivot friends on high speed washboards and fast downhill rocks (e.g. Baldwin, Rocky Ridge). Also, I believe the compliance helps get up and over things nicely sometimes (nicer than my virtual buds). Haven't had the pleasure of a direct comparison ride w/ a DW, just w/VPP.
Like Stripes, I'm still waiting for a direct statement of meaning from all this analysis. Are you saying a Ventana design wastes energy that a DW doesn't, or that it rides worse or harder under certain conditions, or doesn't climb well? Come on, we can handle the "truth" (as you see it).
K
Most peope do not like their bikes to bob and squat a whole lot. This is why every suspension bike company focuses so much on the issue - and it's why the subject is raised so often on the forums.LncNuvue said:I thought the bike accellerated great - i like the way it squats into the travel when you get on it and hammer out of the saddle or brake into corners. I got full travel on pretty much every ride. Sure it can bob but that's why you learn to pedal smooth circles. My DW does a lot of things I like too and some things that I don't. There's give and take with every design. Ventana shouldn't change anything.