K2 / Proflex Riders Group
General => Tech Forum => Topic started by: keen on June 13, 2003, 04:02:04 pm
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I have an 01' Way Big disco Monkey. Psylo XC fork, Stratos Pro rear shock. I ride agressive XC. Everytime I hit the local trails I find that about 80% of the bikes run some sort of multi-link/ 4 link rear suspension. A few Santa Cruz bullits but they have 5th element shocks. Am I missing out running a single pivot? I have only owned/ ridden 2 full supension bikes - 97' Beast and the Monkey. Specialized Enduro's seem interesting but I haven't had any real experience, or what else? Any opinions?
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Sounds like you have a nice setup. You know, you always want what you don't have. Plus, those bikes are 3 or 4 grand .The rear suspension technology is what has changed . Stable platform definitely makes a difference, but not needed to have a good time. It all amounts to less bob. I wouldn't worry about it unless you're ready for a new bike. Rich
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See if your friends will let you try their 4 bar linkage set ups, or test them. I have tested a Trek Liquid, and I don't think it rides any better than my evo.
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I think the Evo is the best bang for the buck for a heavy-duty trail bike. The only weakness I have found is the tire clearance on the swingarm. I have put 2.3s on the back, but mud clearance really suck when things get sticky. I've been running 2.1s in case of those muddy days.
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I have an Oz. This year chose to ride a XC series. Many 4 bars/platform shock bikes but the most demanding, technical course of the year gave me the best race results by far on the simple single pivot. Sound's though you're looking for efficiency so consider the new 5th element air shock if that's the goal. Imho our single pivot delivers a good overall ride and misses only on the boring portions off road such as smooth gradual ascents that remind me of road riding.
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most rear suspension changes (notice i didn't say improvements) are in the order of increased travel and smoothness of ride especially initial travel movemement - small bump absorbtion. on a mono pivot such as ours, the 'bumps' are transmitted in the direction of the seat post and the multi linkage setups, 4 bar, fsr etc., cut the shock to the frame down substantially. but in doing so they are much more prone to 'pedal bob' etc. the newer shocks are designed to reduce or counter the problems with the more recent geometry designs, and can make substantial improvements in the mono pivot design as well.
moving to a new shock such as the 5th or fox will help with bob and shock on the monopivot over the supplied noleen.
a lot of the bike is in the fork, money is well spent there. moving to a new shock in the rear will make a good deal of difference and if you could 'try one out' on your frame, i'm sure you'd agree.
i don't lust over other bikes and their new fangled setups. i usually see it the other way around with many guys asking about my 5 year old, mono pivot rig.
most importantly and something to always keep in mind,
i'd rather be driving a supercharged 67 VW bug than a new Corvette with a poorly tuned engine.
OP
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One more thing to observe:
Many "so-called" 4-link suspensions are actually monopivot swingarms with an overly complicated shock actuation mechanism. The Specialized FSR is the most notable of these.
How do you identify a "pseudo 4-link"? Simple. If there is no pivot between the "main pivot" (i.e. the one nearest the BB) and the rear dropout, then the suspension is actually a monopivot type design. True 4-links have a pivot (sometimes called a "horst link") between the pivot at the BB and the dropout.
Think of it this way. If you take all the links off of the bike except the link connecting the main pivot to the dropout, the suspension travel will be defined by the arc swept out by that link. This is exactly the same as the swingarm on a monopivot design. On pseudo-4 link bikes, the extra links are just fancy ways of actuating the shock (however, they may add modifications to the spring rate - i.e. rising/falling rate - at the expense of extra pivots). On an EVO style frame, the shock is actuated directly by the link.
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Don't forget maintenance. I have ridden a ProFlex 5000 for four years(All year, snow, mud, blah blah) with very minimal maintenance. It is going to take a break as my Oz is a day away from being completed. ;D ;D ;D
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Many "so-called" 4-link suspensions are actually monopivot swingarms with an overly complicated shock actuation mechanism. The Specialized FSR is the most notable of these.
Actually, the Specialized is THE real 4-bar linkage. They own the patent now and other companies pay them to use it (e.g. Giant and Intense). There is most certainly a pivot between the BB and the hub on the Specialized bikes.
Kona and Diamondback come to mind as good examples of the pseudo 4-bar linkage. The K2 Tirade is also a good example.
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I wrote:
"Many "so-called" 4-link suspensions are actually monopivot swingarms with an overly complicated shock actuation mechanism. The Specialized FSR is the most notable of these."
Matno, you are correct....That last sentence was meant to be at the end of the next paragraph and should have read:
"How do you identify a "pseudo 4-link"? Simple. If there is no pivot between the "main pivot" (i.e. the one nearest the BB) and the rear dropout, then the suspension is actually a monopivot type design. True 4-links have a pivot (sometimes called a "horst link") between the pivot at the BB and the dropout. The Specialized FSR is the most notable of these."
Aahh...the vagaries of "cut and paste" [smiley=disbelief.gif]
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;)
That makes more sense. I didn't really doubt your knowledge, you being our resident engineer and all... I just wanted to make sure somebody else didn't misunderstand. I am correct in saying that the Tirade is a "fancy monopivot" though, right? Seems like a lot of extra pivots for a simple design, but it must make SOME difference or you wouldn't see so many of them.
Oh, and Thunderchild: be sure to post pics of your Oz VERY soon. I've been waiting to see this thing for almost 3 years now! :o
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TC posted a thread a couple weeks ago that may be of interest.
http://idriders.com/cgi-bin/YaBB_K2/YaBB.pl?board=news;action=display;num=1054826516
For my two cents, I've ridden a few 4 bars and they are not all equal, just like 98 and later K2's are not the same as 97 Proflex's.
I can say for certain that single pivots kick back over sharp obstacles like roots and rocks far more than the FSR rear end. When folks say the FSR sticks like glue, they aren't kidding.
pic 1. http://www.verdigris-online.com/A2Jam/rider.jpg
This guy nearly face planted into a tree about 15 yards further down.
pic 2 http://www.verdigris-online.com/A2Jam/rider5.jpg
Different section but the same speed and similar obstacle. Note the rear wheel difference.
The K2 single pivot may feel softer, but when the back end is in the air, for even a split second, it's enough to cause real problems. Probably not such a big deal for average trail riding, but when going gets fast and sketchy and you're pointing downhill....
Having said that, on my local tech trail, I've seen a disturbing number of Enduros break. From broken welds to stripped BB shells. I can recall three out of four that I know of just last season.
ps, I run a Stratos Helix Pro on my DM.
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Very clear pics-what's your camera setup? The K2 rider would have much better results if he laid off the brakes, especially the rear to avoid the mono pivot kickback. We (monopivots) give up something in rear suspension action while braking and clearing logs has a way of making this Really obvious and a practiced hand at the bars helps a lot.
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Matno wrote:
"I am correct in saying that the Tirade is a "fancy monopivot" though, right? Seems like a lot of extra pivots for a simple design, but it must make SOME difference or you wouldn't see so many of them."
Yep...I'd consider the Tirade a "fancy monopivot". In fact, the K2 Razorback, Launch, Attack, and Tirade are all "fancy monopivots" in my book. Take a close look at the "swingarms" on all these bikes....notice anything similar? Save for possibly the lengths and/or material, they appear to be identical. The only differences in the suspension portion of these frames are the shock actuation linkage.
The only legitimate reason for having a complicated linkage actuating the shock is to change the shock actuation rates....I think this could be handled much easier with progressive rate springs and/or shock valving a la the 5th element shock.
Otherwise, it's just fashion. In other words "if it looks like a 4 bar, it must be as good as a 4 bar".
Simply a case of "me too" bike design.
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so that's why i keep crashing on logs, I thought it was because i'm a crap rider! Seriously , I can jump off stuff and roll down some steep, gnarly shit no prob, but then I'll slam going over a twig. The Evo back end does bounce a bit at speed, adjusting the shock helps a lot if you can, I'd love to try the 5th Element. I don't find braking to be a big prob, you lose some action but it tends to sit lower rather than jack up, and i don't brake when jumping. To me the Evo is real easy to keep level in the air and land on the rear wheel if needed. It can be a problem if you have to clear a small obstacle on the edge of a drop, tends to kick up the rear as you launch and push the front down, I think that is just bad timing on my part tho'. Tried my friends Dare and it didn't feel any better to me.
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Scott wrote
"what's your camera setup?... "
I was using a Canon G2 for those photos with a Sunpak flash in most cases. The shot of the guy on the DM was in a very dark part of the course and I had to bump the ISO a lot, so there's a lot of noise. The rider on the BigHit was in a fairly bright area plus the flash gave a nicer image.
"We (monopivots) give up something in rear suspension action while braking and clearing logs has a way of making this Really obvious..."
I know there's a lot of dispute regarding brake jack on various suspension designs. I do agree that applying rear brakes on a monopivot does lockout the suspension to some level. Personally I think this is a big flaw, sometimes you have to ride the brakes!
Tom A wrote
"The only differences in the suspension portion of these frames are the shock actuation linkage."
Regardless of whether or not bike designs are fancy monopivots or not, the varying designs have very different riding characteristics or "feel" to them. I like the EVO style bike for jumps and drops and just fooling around. But, it's nearly killed me a couple times on DH runs though. For XC and also smaller jumping I still vastly prefer the ProFlex 957 over any other bike.
I think I've mentioned snippets of discussions a friend and I had over the course of the summer of 2000 regarding xc suspension rigs. Both of us had owned or at least ridden a good bit, lots of bikes. We finally came to agree that the best overall xc style was the mac strut monopivot. Noticeably the quickest, most durable, laterally stiffest and best accelerating frames on the market. At that time I was on a Razorback and he was on an off the shelf RacerX. Later I switched back the 957 and he went with a custom RacerX which later became known as the Hammerhead 100X. BTW, we agreed that the X and Razorback were equals as bikes, but with differing TT lengths (that great old Proflex geometry!). My large Rback was the same as his medium X.
So anyway I guess my point is that certainly while "design" is marketable (evidenced by the fact that strut frames are rapidly dying off because they aren't sexy like the newest flavor frame) and 4-bar is the king of marketable right now, minor changes in any design can make a huge difference in ridability. And further, ridability is in the eyes of the beholder.
Finally, shock technology has not progressed as fast as suspension design. It's going to be interesting to see how suspension changes to take advantage of the Romics and the like!
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The reason for a lot of 4bar single pivot designs vs. a larger swingarm is that the 4bar is supposed to resist twisting forces a lot better. the example explained to me was that if you took the axel out of the wheel and place a long steel bar that stuck out the sides by a foot or two in its place, if you lift one side of the bar and push down on the other side, the swingarm will twist far more than the 4 bar linkage. i don't know how that really translates to real world riding since any twist like that will deposit you on the ground if you are trying to balance on two wheels, but that's the explanation for the linkages on a lot of monopivots.
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I came across a pretty good website that takes an in depth look @ suspensions : dougal.co.nz . He discusses Horst link , seat stay , and mono pivot suspensions in detail. Horst link sounds good to me. The brake jack associated w/ mono's is a big negative for me. I was considering a Kona Bear until I found out that all 4 bars arn't created equal. I would like to find a horst link style rear w/ at least 4" of travel.
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Somebody was mistaken about the FSR. The FSR is a "horst-link" system and is not like a single-pivot. Many companies don't want to pay licensing fees on the "horst-link" patent and cheat by making a single-pivot with 3 more bars to look like a four-bar. The beauty of the "horst-link"/FSR 4-bar is that the drop out is allowed to move relative to the swing-arm. This is done to keep the distance from the bottom bracket spindle and the rear axle constant throughout the rear travel. The problem with 4-bars is when all those pivots loosen up from wear and tear.
Mike
'99 4000
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Well I am glad I looked into suspensions before I made a purchase. I thought most 4 bars were alike. I like the Specialized design but question its durability. Any other true 4 bars that won't break the bank ? Thanx
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Example; 2001 Enduro Pro Specialized, 2years and many miles , pivots still tight and smooth. They do take a little more care, but not much. 4 bar is a great rear end. You ever heard anybody complain about their Turner, and they use bushings.
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On the other hand, I hear a ton of people raving about the Cannondale Gemini and Santa Cruz Bullit, both single pivot bikes with lots of downhilling in mind. Kind of makes me doubt that the problem of brake jack is all that noticeable. I used to think my EVO frame was bouncy when braking on rough sections, but since I switched to a Helix Pro in the rear, it feels completely smooth. On the other hand, by the time I switched shocks, I had learned not to use the brakes much on really rough stuff. Much safer that way!
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You're right matno. the helix makes a huge difference on the evo frame and really smooths out the trail. If you have your weight positioned correctly (ie. butt hanging back over the rear tire) brake jack is not really a problem on a single pivot frame and you should be rolling the really steep portions or very rough stuff with very little brake anyway. I guess the thing i notice about the fsr vs. single pivot thing is that the evo smooths the trail very effectively and i can hear the rear tire catching and losing traction, skidding and bouncing around while feeling very confident. on the fsr, i can feel a bit more trail action, but there is almost no skidding and you can feel the rear end tracking the contours in a different way. just my 'seat of the pants' impressions. I liked the FSR so much i just picked up another enduro frame(as a spare if anything happens first one.....yah that's it) to add to the stable. I think i have a problem with bike collecting, we (wife and I) now have 6 bikes and 2 spare frames.
-2000 Rocky mountain thin air
-2000 Giant XTC (frame only)
-2001 FSR enduro (one complete bike, one "spare" frame)
-2000 K2 evo
-2001 K2 attack 4.0
-2000 Giant NRS DS1
-2003 GT i-drive
does that count as a problem? As for a medical question? My wife ruptured her kidney in a mountain bike crash 3 weeks ago, got choppered out and spent 9 days in hospital. She's home now and we are signed up to ride the 24 hours of adrenaline in canmore on july 19-20. She's itching to ride it but the doctor says she shouldn't. how long does a ruptured kidney take to heal? It didn't require surgery and the docs said it would make a full recovery. psycho fall, no external bruising and no broken bones/head bonks at all. just squashed her kidney and bruised the organs around that area. Getting info is like pulling teeth with these docs so any info is appreciated. thanks
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Well, I'm no doctor, but I play one on TV... Okay, I just started clinical rotations 2 weeks ago, but I have enough personal experience with my own injuries to know that it's better to just do what the doctor says. It helps if your doctor understands your sport. (When I broke my hand, my surgeon just happened to share an office with my main riding buddy who's a physical therapist. I think that helped him to give me the okay to ride a couple of weeks early).
I would assure the docs that she's not going to be crashing (hopefully!) and see what they say, but ultimately, they should make that decision for you. They tend to know what's best in most cases, which may not apply to your wife, but of course, you're free to do what you want.
On the other hand, she's still got 1 good kidney... I did read an article last year about a guy who won a fairly large MTB race 6 weeks after donating a kidney...
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internal injuries are a bit of a mystery and we all heal at different rates.
never, never, never, never, never, never, never take a chance on internal injuries, especially a kidney and especially if it's not your kidney and especially if it belongs to your one and only wife -
i have friends on dialysis - best to be safe -
not know the extent of the damage, the doctors probably can't tell you because they probably don't know.
i hope she fully recovers and you'll be riding again together someday soon.
OP