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  1. #1
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    Square edge hits and suspension design.

    I have mainly ridden VPP and far designs.
    Can someone share more light fore into this?
    Some people say DWlink is less prone to the negative effect of square edge hits, hanging and pull.
    How are the other designs perform in this area?

  2. #2
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    My old IH Sunday (DW Link) was pretty compliant with square hits likes curbs and stairs while urban riding. Didn't really buck or rattle me when it happened, but it also liked to soak up anything I could get a little air off of.

    Current Transition Dirtbag (Single Pivot/Faux-bar) is a lot more harsh with square hits, but pops off of kickers and soaks up big landings a lot smoother and more progressively than the Sunday did.

    As to how they both compare to VPP, Maestro, 4 bar, or anything else, I have no experience to give you.

  3. #3
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    In terms of DW vs VPP, I don't really notice all that much difference between the two in overall square-edge absorption. They feel a tiny bit different, but perform very similarly. The bigger difference lies in the bikes themselves, not just the brand of linkage. A Nomad will probably have a much cushier feel to it over square edges than a Blur, even though they are both VPP. Same with DW. A DW-Link on a Giant Trance is VASTLY different in geometry and feel than a DW-Link on a Turner DHR because each installation of VPP and DW are tailored to fit the purpose of each bike.

    The more techy answer:
    The best designs at cancelling out square-edge hits will be the design with the most rearward-moving axle path. On both VPP and DW-Link bikes, the axle path is often very linear, meaning that it doesn't follow the forward-arc path that very old single pivots used to have. This is dictated by the length of the linkage pieces, and the angles they sit at. It follows a line more or less tangent to the circular path, giving it a bit more rearward 'absorption' of the travel when you hit square edges. Mind you, linear axle paths are not usually considered rearward axle paths, even if they do equate to a bit of chain growth. But if you take something like the super sweet Canfield Jedi DH bike, that thing has 9 inches of upward travel, and 2.5" of rearward travel. So as the suspension compresses, it moves backward too. That rearward movement allows the bike to maintain its forward momentum much better, because it absorbs the impact: the rear wheel moves upward and backward, not getting hung up on the edge, resulting in much less momentum lost to the impact. The problem with rearward axle paths is that they equate to a lot of unwanted chain growth. That tugging and slackening of the tension on the chain is not good. Canfield created a very interesting idler pulley design to counteract that, making an effectual parallelogram that cancels out chain growth. That may adversely affect DW and VPP's ability to stiffen up under pedaling though, so they just take the easier [read: cheaper] route and create a same-ol linear axle path design and market it as being 'way super deep, plush, bottomless, velvety, etc'.
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  4. #4
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    ... or you can get a horst link and suffer the worst of all worlds. Don't get all butt-hurt people, just my opinion
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  5. #5
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    Look harder at the shock fitted and the rider than the frame layout.

    Bikes with a rearward enough axle path to actually make a real difference across 'square edges' are few and far between, they generate so much chain growth that an idler is needed. Aside from Canfield I can't think of any DW-like layouts that have that extreme of a rearward axle path.

    Also, a lot of people attribute to the frame layout things that are better explained by shock setup or technique. Dragging the brakes across ruts will feel crap on any type of bike, whilst poorly tuned and set up (or simply poor quality) shocks generate a lot of the bogeymen riders associate with frame layouts (for example brake squat often comes from shocks with poor high speed damping that simply pack down under stress, which affects all types of suspension much the same).

    Of course you can dispense with thse worries completely if you just buy a hardtail.

  6. #6
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    Fwiw, I find that the lower tire pressures I run, the more I seem to get hung up on square edge hits. It makes sense if you think about it, the rear suspension doesn't respond as quickly because the tire is compressing more/first. There is a trade off to make here...

  7. #7
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    Gt's I drive ( the sanction and force and fury version) Has quite a bit of rearward axle path.


  8. #8
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    DW vs VPP vs whatever buzzword doesn't tell you anything about the wheel path or leverage ratio, so it won't be instructive for this. (Or for anything else at all, but that's another argument.) Like charging_rhino was saying, the the bike designers can change everything by changing the pivot and linkage geometry.

    Square hit compliance is mostly a function of how squishy* the setup is, and how much rearward travel the wheel path has. The Canfield Jedi is one of the leaders in rearward traval (as Fix The Spade mentioned). And the Balfa BB7 looks like a solid contender as well. But both are pretty heavy DHers, usually sporting dual crowns (that said, I ride my Jedi all over the place so if you don't mind some extra weight, consider it). And GT's idrive probably comes next (as hitechredneck mentioned).

    You need to be creative with the chain path to accomodate a lot of rear travel, hence the extra pulleys on the Jedi and BB7. Or be creative with bottom bracket motion as GT is doing.

    And there are some straightforward single-pivot bikes with high pivots that look promising, like some of the Moorewood bikes for example. Then its the derailleur's job to cope with the chain growth. I'm leaning toward this approach for my next bike.

    I sure wish manufacturers would start publishing wheel path charts. And leverage ratio charts. Neither are unheard-of, but neither are common either.

    * It's a technical term.

  9. #9
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    My engineering intuition tells me that wheel path itself has nearly zero importance for "square edge hits". The wheel attached to the moving suspension assembly is big (comparing to travel and reasonable obstacle size), lightweight and moves backward (rotates) freely.
    But - wheel path is instrumental in chain-tension based anti-squat action and as such affects desired suspension behavior and tuning.
    In other words - soft and not overly damp suspension action is good for square edge hits but it might cause wallowing when pedaling which could be somewhat compensated by anti-squat design. Which in turn may lead to undesired pedaling feedback etc.
    When braking hard everything is more complicated - but even then path of the wheel _contact_point_ is always "backward" just because of bike geometry (it's like very high single pivot) and small differences in suspension design are not very important in my opinion.
    I played with CCDB settings which change damping significantly - and it affected reaction on square edge hits drastically.

  10. #10
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    I think leverage ratio and shock settings are much more important than and suspension acronyms and axle paths. Many world cup downhill bikes are flattening out their leverage curves in later iterations to keep them fast in the rough.

    People harp of rearward axle paths and in an isolated hit there may be some truth in that, but every time an axle moves rearward in compression, it's moving forward in rebound and that might not be so hot for repetitive hits.

  11. #11
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    It's very true, suspension does have a ton to do with what the rider feels or doesn't feel when hitting a square edge. I've got a CCDBair, and decreasing the high speed compression damping has done wonders for soaking them up. But it's undeniable after riding something like a Jedi: rearward axle paths very much affect square edge hit behavior. That bike soaks them up FAR better than anything else I've ever ridden, regardless of what shock/settings being run. It's on a completely different level than even the most revered VPP and DW-Link bikes like the V10 or DHR. Current VPP/DW-Link/etc chain tension-based pedaling systems do suffer with rearward paths, but it is undeniable when considering only square-edge hit perormance. Axle path does matter. A lot.
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  12. #12
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    I agree with Shepherd. I went from owning Nomads for 3+ years, demoed a friends single pivot Yeti ASR-7 and was blown away, sold my carbon Nomad in favor of my own ASR-7. I fell in love with active suspension and have since owned a few others. My fave so far is the Knolly 4x, currently building a Warden. Simply eliminates square edge where the VPP would get hung up and feel sluggish. Many climbers will squawk at active suspensions saying they give up too much efficiency but todays shock tech balances that out in my opinion. Active suspensions are so much fun to climb steep tech as well, staying glued to the terrain with a floating over feel.

  13. #13
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    ^ This. I ride a Canfield One, and it's got 8" of very active suspension. I couldn't agree more. It's fantastic. Especially when things get chunky, I can float up things that others impact then spin tires on. On most climbs around my house, I get faster climb times on the trails with my Canfield than I ever did with a lighter, more 'efficient feeling' DW-Link bike. It doesn't feel like it while pedaling, but the clock doesn't lie. I still like VPP or DW if I'm riding up heinously long fire roads, but other than that, I prefer an active rear wheel.
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  14. #14
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    What kind of square edge hits are you guys hitting with your rear wheels? I guess I'm having a hard time envisioning what those things would actually look like on home trails (laguna, ca). Even going down stairs isn't square, and I don't know anyone who intentionally rides their bikes into curbs at 25 mph without at least trying to un-weight :/ Maybe I'm just hanging out with the wrong groups though >_>

    Thinking back to my time in new england I can definitely think of some square-edge brutal trails, but they were never anything you'd need 8" of travel on, you simply can't ride them that fast.

  15. #15
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    How about climbing?
    Is the bikes suspension behavior in regards to square edge hits effected differently on climbs than descents?

    My main issue with hanging on rocks was on technical climbs.

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    Aah, interesting. Growing up in NE I guess I just learned to muscle the bike with my upper body over stuff. Riding tech on a 20" frame hard tail c-dale (in the early 90s) when you're 5'7" was interesting, heh.

    A technical 'up' in OC that I can think of off the top of my head is over at Oaks, the 'waterfall' section at the top of chutes. While it doesn't have many square edges, I'd say 90% of being able to climb that is to toss the bike over things with your upper body. I'd venture it's the same with square edges - you don't want to pedal over them, you want to plant and just toss the bike up/forward.

    Maybe some people from Sedona will chime in

  17. #17
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    Quote Originally Posted by probiscus View Post
    Thinking back to my time in new england I can definitely think of some square-edge brutal trails, but they were never anything you'd need 8" of travel on, you simply can't ride them that fast.
    The North of England (and Scotland) is full of trails built on slate, it's not so much square edge as every kind of edge you can imagine, indefinitely. The sandstone I ride about on locally is full of nice sharp edges thanks to the rain cutting it up all year too.

    Also, waterbars, fecking waterbars are everywhere round here.

  18. #18
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    Quote Originally Posted by jazzanova View Post
    How about climbing?
    Is the bikes suspension behavior in regards to square edge hits effected differently on climbs than descents?

    My main issue with hanging on rocks was on technical climbs.
    yes, it is affected differently on climbs. VPP and DW like to stiffen up a lot, and that acts sort of like a lockout. While that may feel efficient, the bike does something bad. When you climb over a tall root, rock, or edge, the back tire hits the edge, hesitates momentarily, climbs up the obstacle, then keeps rolling forward with a reduced speed. That is what is called 'inactive' suspension, because the suspension is effectively locked out due to the tension you are putting on the chain, and the vector of that force (basically the downward angle of the chain).

    Active suspension is what you want if you get that hung-up feeling when doing technical, chunky climbs. The suspension is allowed to move a bit, which absorbs a bit of that hesitation when you impact the face of the edge. That little bit of absorption allows you to keep your forward momentum a bit better. You do have a bit more floaty feeling while climbing, and some may whine about feeling inefficient. But it has made a huge difference for me when climbs get rocky. I can float up almost anything, I don't lose traction, and I keep more forward momentum.

    Regarding DW and VPP, they are both very similar in overall feel while descending, in my book. Same with climbing. Neither are very active when climbing, and both are very smooth while descending. To get a more active suspension feel, you'll probably have to get a bike geared more toward descending, or look for another suspension type altogether that doesn't have such a strong pedal-induced stiffening of the rear triangle.
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  19. #19
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    Re: Square edge hits and suspension design.

    Quote Originally Posted by charging_rhinos View Post
    yes, it is affected differently on climbs. VPP and DW like to stiffen up a lot, and that acts sort of like a lockout. While that may feel efficient, the bike does something bad. When you climb over a tall root, rock, or edge, the back tire hits the edge, hesitates momentarily, climbs up the obstacle, then keeps rolling forward with a reduced speed. That is what is called 'inactive' suspension, because the suspension is effectively locked out due to the tension you are putting on the chain, and the vector of that force (basically the downward angle of the chain).

    Active suspension is what you want if you get that hung-up feeling when doing technical, chunky climbs. The suspension is allowed to move a bit, which absorbs a bit of that hesitation when you impact the face of the edge. That little bit of absorption allows you to keep your forward momentum a bit better. You do have a bit more floaty feeling while climbing, and some may whine about feeling inefficient. But it has made a huge difference for me when climbs get rocky. I can float up almost anything, I don't lose traction, and I keep more forward momentum.

    Regarding DW and VPP, they are both very similar in overall feel while descending, in my book. Same with climbing. Neither are very active when climbing, and both are very smooth while descending. To get a more active suspension feel, you'll probably have to get a bike geared more toward descending, or look for another suspension type altogether that doesn't have such a strong pedal-induced stiffening of the rear triangle.
    Thank you. Good info.

  20. #20
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    Quote Originally Posted by jazzanova View Post
    How about climbing?
    Is the bikes suspension behavior in regards to square edge hits effected differently on climbs than descents?

    My main issue with hanging on rocks was on technical climbs.
    Even though people complain about it being "too active" this is where FSR/HL shines. I had an old Stumpy which climbed over bumps with practically no hang up.
    But, I also had a Reign X, which hung up badly, until I put a softer spring into it, then it rolled and got great traction over roots and smooth rocks. Currently on a Marin MT Vision and it also likes the rear shock to be fairly soft.
    Based on my (limited) experience, virtual-pivot designs are very sensitive to spring rate, most like to be in the 30% sag range to stay "active" under power.

  21. #21
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    I disagree, my FSR bikes (and I have a newer one) suck so much power when climbing due to no anti-squat that it greatly increases the difficulty in steep terrain. It basically gets worse as the terrain gets steeper and you try to ride in the middle ring (as opposed to the granny), which is sometimes the only way to power through technical terrain, as the granny simply makes you spin out. Other designs do not digress anywhere near as bad when it gets steep and you start putting out more power. In particular, I noticed the dw link sucked up the sharp hits much better than my Horst link bikes, while still maintaining the "flat ground" acceleration and efficiency. More than 100% anti squat was an issue back in the day with a lot of high pivot bikes that were put on the market, this was good for rearward path, but bad for suspension action while pedaling, due to the stiffening over 100% anti squat that is generated when you pedal. Most (but not all) single pivot bikes are designed these days to have the chain line close to the front ring, and 2x and especially 1x set ups now allow for good characteristics with less variance between the different front cogs, although not every manufacturer selling a 1x front setup bike has optimized the suspension for it yet.

    Unfortunately, square edge bump absorption has always been poor with my low-pivot Horst link bikes. Horst links are usually, but not always, low pivot bikes, with a virtual pivot very close to the BB pivot. Disregarding the Horst link and adding all of my low pivot bikes together, this does seem to be a common issue. To combat the earlier mentioned uphill pedaling issues, compression damping does help, but it will also further sacrifice bump absorption. I invested a bunch in a custom shock ion two of my FSR bikes to fix the suspension issues, and the investment was worth it, but I realized it was only a stop gap, as I can tell from riding other designs that these issues do not need to exist to the extent they do on the Horst links, and the custom shock did not make my ride equal those.
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    like they say - different strokes for different folks. Demoed most VPP, DW bikes this season. Own a Giant Maestro Anthem 29er - garage queen now - but when new saw everything I could throw at it in CO and UT. Owned a Kona Satori last season and now on the Norco Sight which is the best overall balanced bike ive yet owned. First off - i have really taken to an active rear suspension - and learned that even if the Satori wasnt the most "efficient" climber in the world - if I could keep my ol legs moving - i could tractor up and over anything - inc multiple consecutive stair step type terrain - if I simply showed some patience and felt the bike's sus do what it should. The Sight is even better and the Norco engineered FSR rear works so well - both up and down - i know they optimized some of the pivot points diff from Speshy - so that's likely why its so good. Just sayin - for me its a win. I liked all of this years bikes I demoed - and there was NOT a BAD one in the bunch, and on the same demo loop it was the Sight that made me giggle like a school girl over the others. BTW - I do have the new Debonair rear shock as replacement for the RT that came with it - and its a true delight. no doubt this enhances my perspective on the bike, but even before I bought it - the rt was doing everything fine on the Sight's rear design.

  23. #23
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    I demoed the Norco Range and agree, a great riding suspension. I am super happy with my decision to go for the Warden but the Range wasn't too far behind.

  24. #24
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    Norco claims to have some anti-squat built into their FSR design so that would be a nice combo.

  25. #25
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    The Norco Sight rides awesome. Horst Link is associated by a lot of people with bobbing and poor climbing efficiency because of older Specialized bikes where the design goal was to maximize active suspension and minimize chain influence. Specialized has changed their suspension characteristics a lot of the last few years.

    These days, priority has been taken away from having a super active rear end during climbing. Now less movement during climbing is prioritized at the expense of small bump compliance. Although DW wants everyone to think only the DW link can do this, all the suspension designs these days can be optimized to perform similarly, and most are performing pretty damn well.
    You can design in any amount of anti squat into a HL bike just like you can in any other suspension design. Check out the Anti Squat numbers for the Norco Sight here:

    Norco Sight Carbon 2014 - Linkage Design

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