sinister 'passion'
- Thread starter xy9ine
- Start date
That's the point, the shock won't be compressing or extending. If you were to just remove those two bumpers entirely, you would be able to move the whole rear triangle, shock and all. The linkages would move, the rear axle would travel, but there wouldn't be any pressure on the shock to make it compress. With that extra pivot point and the way the shock is mounted, there are points at which the linkages can move without compressing the damper - the bumpers keep the linkages from doing that.
So I interpret what you're saying as; that if the shock was replaced by a solid bar the suspension is still able to move?
I can't see how that could happen!? The only way the suspension can move (shock rebounding) is if the bottom link is returning to it's sag point while the rear axle is moving in a compressive direction.
I'd like to see what happens with a solid link in there.....
From what I can see, all the bumpers do is limit the range of movement of the bottom link/swing arm assy. and prevent harsh metal to metal contact.
G
I can't see how that could happen!? The only way the suspension can move (shock rebounding) is if the bottom link is returning to it's sag point while the rear axle is moving in a compressive direction.
I'd like to see what happens with a solid link in there.....
From what I can see, all the bumpers do is limit the range of movement of the bottom link/swing arm assy. and prevent harsh metal to metal contact.
G
Yes, that's what we're saying
You could build a pretty simple cardboard or paper model that would demonstrate exactly why there is free travel without those bumpers.
But you're describing a situation that doesn't exist, the bumpers ARE there and limit the movement of the links travel. (I'm pretty sure that if they weren't there, there would still be no "free travel" - I can't see anywhere it cold go. If the shock was attached to the frame I could see your point but as it is attached to the bottom link, whenever the rear axle moves and whichever direction it moves in, the shock is compressed. Put a solid link in there in place of the shock and the whole thing locks up. Or at least that's how I see it.Yes, that's what we're saying
You could build a pretty simple cardboard or paper model that would demonstrate exactly why there is free travel without those bumpers.
If what you're saying were true the thing would just sit on the floor when you sat on it.
You're just missing some points. Hypothetically so it can be understood better than I was writting it Brainyvisions suggested replacing shock with solid beam and removing the bumpers,there would then be movement because normally one of the bumpers is in contact with a part of the suspension.
So my point was the same,but the shock is compressed and the bumpers in place so therefore the shock is damping but against nothing in it's own little floating world,this would be only for a milllisecond before a bumper is contacted unless repetitive bumps are hit,and the only possible noticable affect would be some mild clunking,poor rear traction,and a weird loose ,sloppy feeling rear in some circumstances. Again I may be wrong but it would appear that way.
So my point was the same,but the shock is compressed and the bumpers in place so therefore the shock is damping but against nothing in it's own little floating world,this would be only for a milllisecond before a bumper is contacted unless repetitive bumps are hit,and the only possible noticable affect would be some mild clunking,poor rear traction,and a weird loose ,sloppy feeling rear in some circumstances. Again I may be wrong but it would appear that way.
Gahh this thread really makes me head hurt, really badly. Sinister bikes is not an engineering firm, and certainly no one there cares about anything other than if the bike goes fast and handles well and lasts a few seasons, which it does (and will).
The bike manuals and picks up very well as the stays stay pulled in and the bike is in the first, more vertical wheelpath for that sort of weight transfer action. Teh Huxx are powned.
The bike manuals and picks up very well as the stays stay pulled in and the bike is in the first, more vertical wheelpath for that sort of weight transfer action. Teh Huxx are powned.
No, because the direction in which the axle can freely move is mostly horizontal. Without the bumpers (and actually within some regions even WITH them), you COULD literally put a solid steel rod in there and be able to move the rear axle backwards and forwards (with a small vertical component as well). I have modeled this in Solidworks and it is indeed the case.
This thread is making my head want to explode.
That makes 2 of us.
I've only sketched it out so I'm a long way behind you on that one. Have you got an eDarawing or model of that?
Nah I just whacked it together in Solidworks so that it looked something close to the picture (proportionally anyway). Didn't save it or include the bumpers though. Just sketch it, dimension all the links (so that they have a length, nothing else, except for the two fixed pivots which you want to define relative to each other both horizontally and vertically), put the shock in, dimension it too (so its length is fixed as well), then click the point where the axle would be, and drag it back and forth. You'll see what I mean.
its like the energizer bunny it keeps going and going
Anyone wanna play with this?
Done as a bit of practice to get my hand into Solidworks again, it's all guestimated geometry and it's probably nowhere near scale but it should show the effects pretty much.
PM me and I'll send you a link to the Parasolid.
Done as a bit of practice to get my hand into Solidworks again, it's all guestimated geometry and it's probably nowhere near scale but it should show the effects pretty much.
PM me and I'll send you a link to the Parasolid.
You need to include both bumpers and possibly seat tube.Accuracy is fairly important too.
Seat tube was just for bumper referance,not neccasery.
Looks good.
Looks good.
L
luelling
Guest
I think it looks cool and is a great concept. IMO it doesn't really matter though. People are still kicking ass on pretty basic proven desings, like the Orange. It may feel slightly better but I think the rider makes the most difference. Not that this would deter me from buying one.....I dig concepts like BCDs 2x4 and the two stage bikes
Eh, where did everyone go?
I was watching this thread with heaps of expectation; and all you graphing calculator-types seemed on board for one of these never-ending tech threads. That we don't have any specific measurements off the prototype doesn't seem sufficient to defuse the forum on how this design works.
Also, I'm surprised at all the comments along the lines of "technology has nothing to do with mountain biking". I do understand this viewpoint, but if you really feel this way then why do you care about this thread, or Sinister's new bike? As I see it the whole point of the Passion, and the discussion regarding it, is the novel way its rear suspension functions. If that's not interesting to you then go ride your bike.
Ya friggin Luddites.
And lastly: I do not understand this idea of "free play". When I visualize the rear axle moving I see it moving along a fixed, linear wheel path. One DOF. I mean, the links all have fixed lengths, they're going to rotate in the same fashion every time. The only variable left over is the fact that the whole assembly swings on its own link attatched to the frame. This axis, which I'm arguing you can't call a DOF in reference to the wheelpath, is what's controlled by the bumpers, right?
Oh and what colors will it come in?
I was watching this thread with heaps of expectation; and all you graphing calculator-types seemed on board for one of these never-ending tech threads. That we don't have any specific measurements off the prototype doesn't seem sufficient to defuse the forum on how this design works.
Also, I'm surprised at all the comments along the lines of "technology has nothing to do with mountain biking". I do understand this viewpoint, but if you really feel this way then why do you care about this thread, or Sinister's new bike? As I see it the whole point of the Passion, and the discussion regarding it, is the novel way its rear suspension functions. If that's not interesting to you then go ride your bike.
Ya friggin Luddites.
And lastly: I do not understand this idea of "free play". When I visualize the rear axle moving I see it moving along a fixed, linear wheel path. One DOF. I mean, the links all have fixed lengths, they're going to rotate in the same fashion every time. The only variable left over is the fact that the whole assembly swings on its own link attatched to the frame. This axis, which I'm arguing you can't call a DOF in reference to the wheelpath, is what's controlled by the bumpers, right?
Oh and what colors will it come in?
Well I had a play with it and came up with this and it did seem as though the "free play" contingent were wrong - well not strictly wrong but the ways it can move while not loading the shock are not directions that it would ever see.
Here's an eDrawing of the model - Passion Mockup - hope that works (only works in IE5.5+ - firefox won't have it). Anyone wants a parasolid of it to play with PM me.
I like it. I'm not sure it's the holy grail of suspension design but I like the lateral thinking.
Gaz
Here's an eDrawing of the model - Passion Mockup - hope that works (only works in IE5.5+ - firefox won't have it). Anyone wants a parasolid of it to play with PM me.
I like it. I'm not sure it's the holy grail of suspension design but I like the lateral thinking.
Gaz
There is a new video coverage from pinkbike on the bike from interbike:
http://www.pinkbike.com/news/Sinister-Interbike-2006-Video.html
http://www.pinkbike.com/news/Sinister-Interbike-2006-Video.html
And which directions are "not directions that it would ever see"? Any kind of weight input by the rider = upwards. Square edged bump = backwards and upwards components. Rebound = downwards. Chain pull = forwards. Between these, you've got all directions covered. So is there a new direction that I'm not aware of, like maybe forwards in time, that no forces act in?
The "directions it would never see" refer to the movement with a solid link in place of a shock. The only direction this can occur according the the model I mocked up (admittedly not to scale) is, with a fixed frame, down and back. IE not a loading that the suspension will ever "see". There will always be load on the suspension, either from the rider's weight or the shock rebounding.
There is never a situation once the suspension is at sag where there is a situation like you are worrying about. What have I missed?
There is never a situation once the suspension is at sag where there is a situation like you are worrying about. What have I missed?
That was a good video. So by growing the chainstays over square edged hits, you'd get some interesting pedal feedback. I wonder how much GT would charge him to license their iDrive? 
I want one.
I want one.
Only if you happen to be pedalling at the time of course......
or standing on the pedals, or looking at them....pedal feedback happens when your feets is on the pedals. When the wheel moves back, it's going to pull the pedals backwards...that's going to happen whether you're pedalling or coasting.
If there's any rearward sag, that will cancel out EVERY TIME you pedal.
If there's any rearward sag, that will cancel out EVERY TIME you pedal.
There's not a bike on the planet that gets "pedal feedback" when coasting, is there!?
Watch the crank arm when he pulls back on the swingarm...
When you are airborne, for one...
Yes.....and? What's your point? When the bike is airbourne it doesn't matter what path the axle takes to get back to neutral
Rebound damping takes time,that's the point of it. In this time(however short)there is no shock for the suspension in the window of space provided by the compressed shock. It probably won't be to noticable or make much difference and the flaws may be far outweighed by the wheels superior tracking to the grounds surface.In the air as mentioned above it may produce an uneasy floppy feeling rear or a clunking,who knows.
It's a great idea for alot of problems but it appears to leave some doors open.
I wonder how long the bumpers are lasting,and if the geometry is noticably altering with the rear wheel following different axle paths.
It's a great idea for alot of problems but it appears to leave some doors open.
I wonder how long the bumpers are lasting,and if the geometry is noticably altering with the rear wheel following different axle paths.
when is the jam coming out?
my buddy had a protype. used it for a slope bike
Could you elaborate?
he rides for sinister, on the pro team. hes the man, sasha, look it up. he got it for crankworks colorado. he rides bmx and hardtail, locked out fork, one breaks style. soo he didnt have much of an opinion on the suspension.