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Relative Anti Squat Profiles Published! (finally)

12K views 92 replies 34 participants last post by  smilinsteve 
#1 ·
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.
 

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#52 ·
Right on!

mtnbiker4life said:
It's been my experience as an engineer that it's very easy to criticize someone elses design when you're staring at hardware but a lot harder to come up viable ideas when you're starring at a white sheet of paper or blank computer screen.
Very true. Since this is the internet, I'll throw in my 2 cents: I like the motivation of Iheart to try and quantify a feeling on the bike. How far off the numbers are...who knows.

Though I am curious about Iheart referring to inertia and then talking about F=ma. Those two aren't the same. I'd think if you are talking about leverage ratios and antisquat, you have to be talking about moments of inertia. Which, now that I think about it...that probably is what he was talking about when he (or someone) referred to being about the bike's center of gravity.

I also wonder if that software package is doing a static or dynamic analysis. Yes, a static analysis should give you a fair indication as to a frames ability to resist "bob." However, I'd argue that bob is a dynamic characteristic and doing a dynamic analysis...you need to consider the effect of rider weight shifts as well.

Anyway, I'd say the qualitative sense of the analysis he did though does seem to mach my experience (though I guess limited). Last summer I rented a Heckler with an RP23 in Downieville when I had issues with the ring drive on my CK hub that couldn't be fixed while there. I have a pushed RP23 on my 07 X-5. The heckler with unmodified RP23 felt a lot stiffer under pedaling than my X-5. However, I liked riding my X-5 better, for whatever reason. Also, (I haven't asked Push this myself), but someone on here once had issues with their pushed RP23...felt it was too soft and bobing too much. They reported that after talking to Push...the usually tune down the platform on the RP23 for the Ventanas. So, that may explain why the heckler felt stiffer under pedaling. But again, I liked the ride of my X-5 (same fork on both bikes) much better than the heckler.

And, FWIW, I just finished up my MSME and I've often thought about drawing up a frame in SOLIDWORKS and running an Analysis in ANSYS (which for me...modeling the rider input to the bike would be the biggest challenge). But, I'd rather ride my bike with my free time.
 
#53 ·
Uhhh. I have a Pivot and a El Cap and a El Rey. Engineering analysis aside, which I'm not qualified to perform, I have come to the conclusion that both designs have weaknesses and strengths. My PUSHed Ventanas feel better in the techy stuff. The Ventanas have better mud clearance. The Pivot and my old Blur packed up like crazy. Stiffness of the El Cap is unparalleled (I think). The El Rey and the Pivot are about equal as far as stiffness. The Pivot is a better pedaler. Not outstandingly so, but it is noticeable to me. I can tweak the Rey to be just as efficient, but then I lose the plushness. That being said, my Ventanas still put a smile on my face. I liked my Weyless XP either in AM or XC trim much more than the Blur I had at the time. The way a bike performs for a specific rider is much more important than graphs to me. That being said if the techno stuff turns you on, so be it.
 
#55 ·
+ / -

Does the selection of pivot location always involve compromises? If so, a good designer picks one which maximizes the positive aspects of that trade-off. I believe this to be true of all suspension designs, not just Ventana's. If he ends up with something satisfying the majority of users most of the time has he not chosen well?
 
#56 ·
I like my squatty ventana. I don't have extended fireroad climbs, I have ledgy, rocky, rooty climbs and I like a stiff rear end that is active.

Is it less pedal-efficient? Sure.
Is it more efficient to not have to use body english to get over everything? Sure!

Hey, Iheartarguingaboutbicycles...you have your work cut out for you. You can throw as many scienticians at this as you can hire, but you aren't going to change too many minds that like their Ventanas...and that is the majority of the people on this very quiet board. Good luck with that. You held out pretty well, and starting a new thread was good (note that I haven't really chimed in due to the tone), but you digress again in insulting people. Not going to get sucked into that.
 
#57 ·
squat on climbs is well documented.

Just another reference to it that I posted a long time ago:
CharacterZero said:
Saturday: 16ish mile ride. Good first leg to stretch out the legs and then lots of up/down/technical riding with a few creek crossings and steep switchbacks, followed by a sweeping descent that begs for little braking.

The bike felt great! The TM is a stronger climber than the X-6 was (with the fork at any length). The front end was easier to keep on the ground, especially around uphill switchbacks. On the way down, the rear end felt very smooth, this was running both 5 clicks of compression and 0 clicks compression on the PUSH'd shock. (FWIW, PUSH removes the PP functionality - it is hard-wired based on rider weight/style. The PP lever then becomes a straight compression dampening function.). The performance of the shock is in line with what you expect from PUSH - it felt snappy on acceleration on the flats with minimal compression dampening, but wallowed a bit on the steeper stuff. Then again, I wouldn't sacrifice an active rear suspension for anything, so the bit of wallow is completely acceptable. The geometry is definitely a bit more drop-friendly; it took almost no body english to get the front end up while approaching ledges, just a slight tug. I didn't notice the longer wheelbase. Standover was fine (although close - but the wife says that it can only save us money on a vasectomy). BB height was noticeably lower (both in feeling just a bit lower and a couple pedal strikes in sections that I hadn't had before). .
 
#58 · (Edited)
CharacterZero said:
I like my squatty ventana. I don't have extended fireroad climbs, I have ledgy, rocky, rooty climbs and I like a stiff rear end that is active.

Is it less pedal-efficient? Sure.
Is it more efficient to not have to use body english to get over everything? Sure!

Hey, Iheartarguingaboutbicycles...you have your work cut out for you. You can throw as many scienticians at this as you can hire, but you aren't going to change too many minds that like their Ventanas...and that is the majority of the people on this very quiet board. Good luck with that. You held out pretty well, and starting a new thread was good (note that I haven't really chimed in due to the tone), but you digress again in insulting people. Not going to get sucked into that.
I can't tell if people simply don't understand what I am saying or are reading into what I am saying - but I am absolutely NOT arguing against ventana bikes as a whole. I am explaining with a level of exactitude the reasons why the bikes squat. This thread is a response to many, many threads posted on the subject wherein several users try to ascertain what the problem is. The problem is very specific.

With regard to technical climbs - you're absolutely right - my 6" travel bike is much better than either my 4" travel bike or even my hardtail - no question about it. I would even go so far as to say an active single pivot (in my case I have a Foes FXR, but it would probably hold true for the Ciclon and Terremoto as well) would climb better than a DW link!

BETTER THAN A DW LINK!

Because DW's stiffen noticably when pedalling, they do stiffen up and will skip a little over rocks.

I have owned the DW's and can make this comparison directly. It's one of the reasons I dropped the DW for my "all mountain" bike.

But with regard to a specific problem/question - the squatting that is so noticable with my Salty is directly due to the main pivot placement and lack of antisquat. So many other single pivots do not have this problem and that information is easy to come by.

With regard to "digressing into insulting people" (sic) go back and read the thread - I've only used the term "fanboi" and suggested people keep their heads in the sand - meanwhile I am called several names and no one seems to think anything of those.
 
#59 ·
iheartbicycles said:
With regard to "digressing into insulting people" (sic) go back and read the thread - I've only used the term "fanboi" and suggested people keep their heads in the sang - meanwhile I am called several names and no one seems to think anything of those.
Sorry, you are correct, you don't insult anyone in this thread.
No doubt there are some real fanbois around here.
 
#60 ·
mtnbiker4life said:
I think iheart did a great first swag at the analysis but like I stated in my posts it needs to be substantiate with mainstream analysis software coupled with hand calculations.....not forgetting a viable engineering test plan. Anything less is a SWAG with pretty pictures.

I like my Ventana with the good, bad and ugly. I like Sherwood....he's a great chap. Like most posters here they may or may not understand all the physics behind FS bikes. That doesn't discount their opinion on the fit, feel or performance of any FS bike. It's an opinion.

Since we're offering up design challenges here list up your half dozen things.......can you hand out hard calculations what you don't like or could better about your bikes? I don't think anybody here has their head in the sand....they are riding what they like for reasons told and untold. I personally would like to own a Turner if they did semi-custom front triangle changes like Ventana offers but they only offer color changes. So that puts Turner off of my list.

It's been my experience as an engineer that it's very easy to criticize someone elses design when you're staring at hardware but a lot harder to come up viable ideas when you're starring at a white sheet of paper or blank computer screen.
I haven't forgotten about this and I still intend to check all measurements myself. My guess is you will once again raise the bar or change the level of proof required.

That's ok. People who read this thread will make up their own minds. For me, I am always learning and you have actually caused me to think beyond what most people do.
 
#61 ·
iheartbicycles said:
I haven't forgotten about this and I still intend to check all measurements myself. My guess is you will once again raise the bar or change the level of proof required.
The level of proof required is totally governed by how much creditability you wish to gain from the results you have put forth. Since, this topic is related to physics and engineering, I have mealy stated what you need to provide to be taken seriously in the engineering community. I am not saying your results are wrong and some on mtbr may blindly take them as absolute truth. But as an engineer, I have to ask for some test methodology if I am to take these results as reliable analysis.

iheartbicycles said:
That's ok. People who read this thread will make up their own minds. For me, I am always learning and you have actually caused me to think beyond what most people do.
I'm a little confused about this statement. Because you have stated there are folks on this forum that do not understand the physics regarding this type of analysis so they really can't make up their own minds, can they? I am sure there is a way to present this data so the lay-person can understand your methodology.

-
 
#62 ·
mtnbiker4life said:
I'm a little confused about this statement. Because you have stated there are folks on this forum that do not understand the physics regarding this type of analysis so they really can't make up their own minds, can they? I am sure there is a way to present this data so the lay-person can understand your methodology.

-
Ventana fanboi's aren't the only people who read this forum. Those with an open mind and a little technical knowledge will see the thread for what it is.
 
#70 ·
There is no magic bullet. Even if you have 100 pivots., ther is no getting around axle path/chain growth relative to the bottom bracket.(chain tension induced "anti squat") etc. Suspension performance is relative to the rider/style of riding. There are many types that have different charecteristics. Pick your poison. 1st gen VPP's have a lot of chain growth (chain tension induced "lockout"). So much so, that if set your chain up too short, compressing the suspension will rip the rear derailure off. Any suspension design can have a lot or little chain growth. The only thing unique I see about DW, is the chain growth has been tuned to be chainring dependant (or at least more so than other designs). That's why the man himself says the hammerschmidt will not work well with his design. Although I'll bet it works just fine for some people. The terrain on this planet as well as riding styles are too diverse for any single design to be "better" than another. This doesn't even take execution of the design in to account, which is a huge factor in performance.

my .02
 
#71 ·
This is very well put. Each rider will have preferences and a riding style that is met better by one design over another.

Your $0.02 is in reality, the gold standard.
 
#73 ·
Gruntled said:
Oh yes, climbing a La Bruja? Either dial in so much propedal that the shock doesn't work, or suffer the squat, the bob and the pedal strikes.
So answer this question - did you test ride the Bruja before you laid down that much cash? With all the shops and the Ventana demo program it's hard to put blame on the frame when it didn't work for you. I don't ride a Ventana because I'm a local "Fanboy" I ride one because it works for me. I also have other branded bikes. If I were to consider spending $2500 on a frame, better believe I would be taking a long hard demo or buy used.
 
#74 ·
iheartbicycles said:
Ventana fanboi's aren't the only people who read this forum. Those with an open mind and a little technical knowledge will see the thread for what it is.
I have never owned a Ventana but I can tell you that I'm a big fan. I could care less about anti squat theory. If it fits and feels good..it is good. The whole is the sum of the parts and that seems to be the main reason why the vast majority of Ventana owners are happy with their rides.
 
#75 ·
ronny said:
. If it fits and feels good..it is good. .
Did you miss all these threads?

http://forums.mtbr.com/showthread.php?t=521496&highlight=squat
http://forums.mtbr.com/showthread.php?t=554008&highlight=squat
http://forums.mtbr.com/showthread.php?t=519587&highlight=antisquat
http://forums.mtbr.com/showthread.php?t=549557&highlight=antisquat

Ventana's bob worse than just about any other bike out there. They have lower antisquat than any bike I know of. Yet all the Ventana fanboi's answers to the problem is to run tons of compression damping (propedal) to hide the problem.
 
#76 ·
Read em all and you seem to be the loudest voice on each thread. I know what you are getting at and you actually come across quite logically in most of the threads. Ventana bikes are single pivot and the pivot placement is pretty much the same on all the bikes except the dh model. I know that Ventana is going to bob a little more than most brands with a higher pivot placement or different suspension design. With that said, the vast majority of Ventana riders are happy with their rides. As said previously, the whole is the sum of the parts. Always a compromise.

One thing I am wondering is there is rarely any complaints about the Terremoto with excessive bob or squat. The pivot placement seems pretty low. I wonder if there is less complaints because Terremoto riders are using coil shocks or what? Does the extra travel mask the problem or would the bike not wallow in it's travel even more? Moto users please chime in. IheartVentana, what are your thoughts?
 
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