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any of you guys read these articles?

dhkid

Turbo Monkey
Mar 10, 2005
3,359
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Malaysia
http://www.santacruzbikes.com/news/index.php?JoesCorner=1&display=2

http://www.santacruzbikes.com/news/index.php?JoesCorner=1&display=1

is it just me or are there some fundamental flaws in those articles?

" If that pivot is above the chain-line, the bike will exhibit anti-squat (the suspension extends)characteristics when the chain is under tension while pedaling. The opposite is true when the pivot is lower than the line of force in the chain."

he just talks about that and nothing about the line between the rear tires contact patch and the intersection point between the vertical linem of the front tires contact patch and horizontal line fro the riders center of gravity.

and even better is how axle paths dont matter!!

if this guy is really the head engineer for sc, i would be worried.
 

Steve M

Turbo Monkey
Mar 3, 2007
1,995
23
Whistler
Yep, he's pretty full of crap. Be interesting to drag em into an internet argument about it... I'm sure THEY think they're right but there are plenty of flaws in both those articles, including the way in which they postulate chaingrowth is caused.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
i do give him a little credit for manning up and saying their marketing with the v10s s curve axle path was total rubbish. but from the new and updated crap he has in those articles i dont think he deserves any credit.
 

Steve M

Turbo Monkey
Mar 3, 2007
1,995
23
Whistler
i do give him a little credit for manning up and saying their marketing with the v10s s curve axle path was total rubbish. but from the new and updated crap he has in those articles i dont think he deserves any credit.
Yeah for sure - I think he THINKS he's being honest (which is good, and acknowledging that their previous marketing was false gets two thumbs up in my book) but on some stuff he's just flat out wrong.
 

ChrisKring

Turbo Monkey
Jan 30, 2002
2,395
4
Grand Haven, MI
I would cut him some slack since he might be trying to simplify it so that average people will understand it. Just look at the number of times DW has tried to explain this exact same thing and many people still don't understand it.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
no can do man, there is a difference between simplifying stuff and just being plain wrong.

read his article about axle paths not making a difference. so is the only main difference between say, a blindside and a bb7 the leverage ratio?
 

ÆX

Turbo Monkey
Sep 8, 2001
4,921
0
amarillo
[
and even better is how axle paths dont matter!!

if this guy is really the head engineer for sc, i would be worried.


Basically, the center of your rear wheel can't move much more than 20mm in distance from the center of the bottom bracket or your pedals feel like they are getting tugged around a lot. ............


yeah, he would not dare mention roller @ high pivot or two chain rigs
that allow no chain growth.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia


Basically, the center of your rear wheel can't move much more than 20mm in distance from the center of the bottom bracket or your pedals feel like they are getting tugged around a lot. ............
how accurate that number is i dont know, but his augment in that bit is correct. that is only referring to chain growth.


Here's something that nobody wants to hear: Axle path doesn't matter for bicycle suspension. At least, it doesn't matter nearly as much as some people say.


axle paths make big differences in how your suspension will react when it hit a bump doesn't it? he is saying it doesn't matter.
 

Heckled

Chimp
Feb 1, 2006
19
0
axle paths make big differences in how your suspension will react when it hit a bump doesn't it? he is saying it doesn't matter.
Axle path, he's right - all he's saying is that its not the most important point of suspension design; dynamic leverage ratio etc. have a much bigger role - it doesn't matter how good your path is if the rest of the system is wack!
 

Sandwich

Pig my fish!
Staff member
May 23, 2002
16,146
1,108
01776
Axle path, he's right - all he's saying is that its not the most important point of suspension design; dynamic leverage ratio etc. have a much bigger role - it doesn't matter how good your path is if the rest of the system is wack!
agree-
it's not the be all end all of suspension design, so it's not as important as some people think...but it still plays a role. IMO it's more important than he makes it out to be...kind of like counter-marketing, but there are so many factors that go into a suspension design...it's unfair to say one is the most important.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
ahh, alright then, good to see you guys are looking at it in a different way. so its just me then. its one of those glass half full or half empty situation.
 
Apr 16, 2006
392
0
Golden, CO
- agreed that too many people put wayyyy too much emphasis on axle path. It's was and and probably is still what most people who read mba etc. and think they know everything buy bikes for, its easy to market and simple to explain to the general public. Sure rearward paths are nice, but how much is too much? drastically changing wheelbase=changing Cog right? I agree with the guy in the article that chaingrowth to an extent is not good, but anyone can tell you that.
 

sanjuro

Tube Smuggler
Sep 13, 2004
17,412
0
SF
http://www.santacruzbikes.com/news/index.php?JoesCorner=1&display=2

http://www.santacruzbikes.com/news/index.php?JoesCorner=1&display=1

is it just me or are there some fundamental flaws in those articles?

" If that pivot is above the chain-line, the bike will exhibit anti-squat (the suspension extends)characteristics when the chain is under tension while pedaling. The opposite is true when the pivot is lower than the line of force in the chain."

he just talks about that and nothing about the line between the rear tires contact patch and the intersection point between the vertical linem of the front tires contact patch and horizontal line fro the riders center of gravity.

and even better is how axle paths dont matter!!

if this guy is really the head engineer for sc, i would be worried.
Ok, explain to me how this is a flaw, and could you prove it to me by showing me which bikes you design/engineer/manufacture?

Cause Joe is a real guy who is making real bikes.
 

go-ride.com

Monkey
Oct 23, 2001
548
6
Salt Lake City, UT
I think axle path is important in that it determines chain growth. However, many of the companies out there promoting certain characteristics about their axle path are not telling the truth. Many who claim a "vertical" axle path are just plain lying. In truth many of the FSR bikes have a decidedly forward axle path that makes them pedal well in the granny, but poorly elsewhere. Ahh… no need to start a big argument, but there is a lot of BS out there and MBA is more than willing to spread it if you pay enough for advertising.
 

Dogboy

Turbo Monkey
Apr 12, 2004
3,130
251
Chapel Hill, NC
Axle path, he's right - all he's saying is that its not the most important point of suspension design; dynamic leverage ratio etc. have a much bigger role - it doesn't matter how good your path is if the rest of the system is wack!
Pretty much how I interpreted it. Basically he is saying there is an overemphasis put on certain aspects of suspension design when in reality you have a very narrow window of usable ranges (like chain growth) and everything else is important too. Just my take FWIW.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
Ok, explain to me how this is a flaw, and could you prove it to me by showing me which bikes you design/engineer/manufacture?

Cause Joe is a real guy who is making real bikes.
i cant prove it by your terms since i dont make bikes.

but its a fact that anti squat or pro squat has nothing to do with the chain or where the chain force is.

(of course unless he is really simplifying stuff and i am just misinterpreting it again like the axle path thing.)

anti squat/pro squat has to do with where the instant center is in relation with the line that connects the rear contact path and the point of intersection between the horizontal line that intersects the vehicles center of mass and the vertical line from the front tires contact path.


honestly, i am not doing this to start arguments. read my post again, i am asking other ppls opinions also, coz i cant believe that those write ups can be as wrong as i think they are. as with the axle path bit, i was wrong and misinterpreted it.

coz if he is trying to clear up the marketing bull **** and making any errors in those post then he is not any better is he?


anyways, i got a feeling that this thread might go downhill fast. i'll see you guys in the morning. going out now.
 

sriracha

Monkey
Jun 9, 2006
496
0
805
didn't read the articles.

all i know is that my V10 pedals great, handles great and feels fycking smooth as baby poo mobin' over rocks.

and i have friends with nomads that say the same thing.
 

Heckled

Chimp
Feb 1, 2006
19
0
i
but its a fact that anti squat or pro squat has nothing to do with the chain or where the chain force is.
While placing drive force in the way that you suggest will have an effect on acceleration squat, again this is not the only aspect to consider, anti-squat is the sum of all of the factors reducing acceleration induced compression of the system.

Using chain torque is a very direct way of doing this, and very effective if implemented successfully (as part of a larger strategy), but the pitfalls of too much drive-chain interaction, ie Pedal Kickback etc. is a guaranteed recipe for bad design.
 

Alloy

Monkey
Aug 13, 2004
289
0
thousand oaks, ca
didn't read the articles.

all i know is that my V10 pedals great, handles great and feels fycking smooth as baby poo mobin' over rocks.

and i have friends with nomads that say the same thing.
Yeah, the guy makes awesome bikes... more people listed the Nomad as their favorite bike of all time than anything else... who cares what his article says.

...On second thought didn't he make fun of forum tech geaks? Is that why you dug this up?
 

Steve M

Turbo Monkey
Mar 3, 2007
1,995
23
Whistler
but its a fact that anti squat or pro squat has nothing to do with the chain or where the chain force is.

(of course unless he is really simplifying stuff and i am just misinterpreting it again like the axle path thing.)

anti squat/pro squat has to do with where the instant center is in relation with the line that connects the rear contact path and the point of intersection between the horizontal line that intersects the vehicles center of mass and the vertical line from the front tires contact path.
Sorry but that's flat out wrong - that kind of analysis ONLY applies to vehicles where the rear wheel is turned directly by a couple moment (ie shaft drive) and most definitely NOT to any kind of bicycle or normal chain-driven motorcycle.

He is however wrong about what causes extension/compression, and still has the false belief that change in BB-axle distance is directly proportional to actual chain extension.

The reality is that most people, including most of the people who design everyone's favourite bikes, don't understand this stuff fully. In this case, the SC guy is no different.
 

sanjuro

Tube Smuggler
Sep 13, 2004
17,412
0
SF
Sorry but that's flat out wrong - that kind of analysis ONLY applies to vehicles where the rear wheel is turned directly by a couple moment (ie shaft drive) and most definitely NOT to any kind of bicycle or normal chain-driven motorcycle.

He is however wrong about what causes extension/compression, and still has the false belief that change in BB-axle distance is directly proportional to actual chain extension.

The reality is that most people, including most of the people who design everyone's favourite bikes, don't understand this stuff fully. In this case, the SC guy is no different.
And once again, what bike did you engineer?
 

EVRAC

Monkey
Jun 21, 2004
756
9
Port Coquitlam, B.C., Canada
Sorry but that's flat out wrong - that kind of analysis ONLY applies to vehicles where the rear wheel is turned directly by a couple moment (ie shaft drive) and most definitely NOT to any kind of bicycle or normal chain-driven motorcycle.

He is however wrong about what causes extension/compression, and still has the false belief that change in BB-axle distance is directly proportional to actual chain extension.

The reality is that most people, including most of the people who design everyone's favourite bikes, don't understand this stuff fully. In this case, the SC guy is no different.
So I'm in an mech. engineering degree program and they certainly aren't teaching this there, so where can I learn about this? I've read some of Tony Foale's articles, but is there anything bicycle-specific?
 

djamgils

Monkey
Aug 31, 2007
349
0
Holland
And once again, what bike did you engineer?
And what bike did you design to be in the position of questioning their authority (is that a correct sentence).

So I'm in an mech. engineering degree program and they certainly aren't teaching this there, so where can I learn about this? I've read some of Tony Foale's articles, but is there anything bicycle-specific?
I guess at school they wont teach you specific bycicle dynamics. But at our school you get multibody dynamics, vehicle dynamics. Alltough the lectures are aimed at cars and trucks you should be able to translate that to bicycles.

To be a bit on topic. I have the idea that the articles are very basic and simplified. I could be wrong but I think there are only a few people who know whats really going on and it could be the guy from santa cruz but it doesnt show from these articles.
And for the record, I dont know whats going on, hope to know it in a couple of years.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
Sorry but that's flat out wrong - that kind of analysis ONLY applies to vehicles where the rear wheel is turned directly by a couple moment (ie shaft drive) and most definitely NOT to any kind of bicycle or normal chain-driven motorcycle.

He is however wrong about what causes extension/compression, and still has the false belief that change in BB-axle distance is directly proportional to actual chain extension.

The reality is that most people, including most of the people who design everyone's favourite bikes, don't understand this stuff fully. In this case, the SC guy is no different.
ohh, whoops. i'll have to get you to explain it for bikes some time then.
 

Steve M

Turbo Monkey
Mar 3, 2007
1,995
23
Whistler
So I'm in an mech. engineering degree program and they certainly aren't teaching this there, so where can I learn about this? I've read some of Tony Foale's articles, but is there anything bicycle-specific?
Get Tony Foale's book or any similar moto-related stuff, it all pertains to bicycles too in terms of what geometry causes what reaction. The only thing is the priorities on bikes and motos are a bit different - removal of "bobbing" isn't something motos have to deal with for example, and their centres of mass are a lot closer to fixed.

And once again, what bike did you engineer?
What have you built? Since it's nothing, shut up, you contribute nothing. If you want to have a technical discussion, do so, but I assure you I have a fairly good idea what I'm talking about.
 

binary visions

The voice of reason
Jun 13, 2002
21,663
411
NC
And once again, what bike did you engineer?
That's such crap, dude.

Not having designed and made the specific item you're questioning doesn't mean you have no right to point out flaws with it. My computer expertise is with hardware and application troubleshooting mostly, but that doesn't mean I don't know a shoddily programmed piece of software when I see it.

Engineering concepts can be discussed without having personally applied them to the subject in question.
 
Apr 16, 2006
392
0
Golden, CO
ohh, whoops. i'll have to get you to explain it for bikes some time then.

Yea same here. There should be a stickey'd post with a basic diagram and FBD and a brief general explanation of the correct role bump, pedal and braking forces play in bicycle suspension dynamics - with content only able to be added by the knowledgeable few (i.e. DW) so that we dont need 5 pages of every rear suspention related post designated to reteaching known physics and theorys of the bicycle sort. :lighten:
 
Oct 14, 2007
394
0
So I'm in an mech. engineering degree program and they certainly aren't teaching this there, so where can I learn about this? I've read some of Tony Foale's articles, but is there anything bicycle-specific?
I feel you, taking the same thing at McGill U, no similarity what so ever
 

HAB

Chelsea from Seattle
Apr 28, 2007
10,605
917
Seattle
I was amused by his geo post. Basically he said "don't worry about geo, we've got it all taken care of." I find this funny, because I have issues with the geo of a lot of their bikes. BB heights are often too high, CS too long, etc.



Is the VPF no more? I don't see it on their website...
 

no skid marks

Monkey
Jan 15, 2006
2,514
26
ACT Australia
Axle path, he's right - all he's saying is that its not the most important point of suspension design; dynamic leverage ratio etc. have a much bigger role - it doesn't matter how good your path is if the rest of the system is wack!
So if we forget steering for a second,do you think it wouldn't matter much if you ran your front forks facing the opposite direction?
 

HAB

Chelsea from Seattle
Apr 28, 2007
10,605
917
Seattle
So if we forget steering for a second,do you think it wouldn't matter much if you ran your front forks facing the opposite direction?
Well, the axle path is going to be very, very close to being exactly the same (except for being shifted back slightly), so uhh... yeah... Steering will be fubar though.
 

no skid marks

Monkey
Jan 15, 2006
2,514
26
ACT Australia
Well, the axle path is going to be very, very close to being exactly the same (except for being shifted back slightly), so uhh... yeah... Steering will be fubar though.
No I didn't mean just turn the forks 180 in the headset,I meant if the forks ran pointing backwards so the wheel was trailing. So the front axle would be near the BB and the headset out in front. Impossible I know,but my point was,would they work as well if they weren't pointed towards the bumps.
 

HAB

Chelsea from Seattle
Apr 28, 2007
10,605
917
Seattle
No I didn't mean just turn the forks 180 in the headset,I meant if the forks ran pointing backwards so the wheel was trailing. So the front axle would be near the BB and the headset out in front. Impossible I know,but my point was,would they work as well if they weren't pointed towards the bumps.
I see what you're saying, and no, I don't imagine that would work worth sh*t. That said, that's a way bigger difference than any variations in rear wheel axle path. You're talking about a HUGE change, whereas the deviation in rear wheel paths isn't all that big.
 

Steve M

Turbo Monkey
Mar 3, 2007
1,995
23
Whistler
I see what you're saying, and no, I don't imagine that would work worth sh*t. That said, that's a way bigger difference than any variations in rear wheel axle path. You're talking about a HUGE change, whereas the deviation in rear wheel paths isn't all that big.
True, but it's a legitimate point all the same - to claim that axle paths "don't matter" is flat out wrong, they can make a world of difference to bump absorption (in the macro scale - how rearwards they are, small changes obviously make much smaller differences) and pedalling efficiency (on a tighter scale - they have to be tuned relatively accurately there). If you limit the acceptable chain extension then yeah there's less deviation, but I thought it was a bit funny of them to go "more than 20mm is too much" then "we have 30mm on the V10". It's ok, that's only 50% more than what you deem acceptable...

That diagram about Jagged Peaks of Anti Squat and the Pro Squat Volcanoes was pretty funny though. Wrong, but funny.

Edit: I sound like I'm being a bit harsh here. I will give SC full points for being open/honest about previous mistakes, and in that geometry article they even say "we make plenty of mistakes". For the record, I think their bikes are pretty cool, they just haven't nailed suspension dynamics yet. Just read that bearings one too - ok I haven't seen this kind of openness from any bike company so far. Kudos for that.