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  1. #1
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    Here's a horse to beat - Horst vs. VPP vs. Split Pivot vs. ...

    I didn't find a thread (insert crappy search function comment here) specific to a discussion of rear suspension linkage. Having ridden single pivot, faux bar, four bar, & DW Links I think I like DW the best. It's not really fair given the different geo of each of those frames, but how important is the rear linkage to you when deciding on a new MTB?

  2. #2
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    These days, not really important at all.

    Originally, all of the "named" suspension designs had a specific, coherent goal that they tried to achieve. These days, pretty much all of the designs have strayed or completely abandoned that original goal.

    You can make almost all of those designs produce leverage curves and kinematic numbers that are at least approximately similar. It's not really possible to describe what a bike's curves look like solely based on the rough layout of the pivots.

    Each design still has inherent upsides / downsides, but those have more to do with stiffness, cost to produce, bearing loads, etc., and I don't find any of those factors to be compelling enough to really affect my buying decision.

    And to be clear, this is not to say that I think all rear suspension designs are created equal. It's just that I don't think there's any one type of design that is clearly superior for every purpose, and in every iteration.

  3. #3
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    I like full suspension that doesn't wallow or bob, and doesn't require flipping a switch to make it pedalable uphill. I generally like the "two short links" type of bike, with DW link the one I have the most time on, over a series of Ibis bikes. OTOH, I hated the first generation Tallboy I briefly had. Yet the Intense 5.5 VPP was fine (as far as the rear suspension). If I have to choose between better climbing vs plusher descending, I'll take the climber.

    The horst link bikes I've ridden have been wallowing yet plush Specialized bikes. I asked somewhere else here if horst bikes have improved that feel, and pedal better now, and someone said they have.

    I have a split pivot Devinci currently, which pedals fine - not quite as good as the Ibis Ripley it replaced, but totally acceptable to me. Also have a Diamondback Release which has a VPP type linkage, and climbs OK - I think the biggest difference in climbing feel between the bikes has to do less with the suspension design and more with the seat tube angle and tires: the Diamondback has a DHR II and a slacker STA.

    Interested to see what others think on this topic.
    Quote Originally Posted by powder11 View Post
    if you have to resort to taking advice from the nitwits on this forum, then you're doomed.

  4. #4
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    What Toast said.

    The various name brand designs differentiated themselves far more 10-15 years ago, when designers were figuring out what worked in terms of kinematics. Leverage and anti-squat curves in particular have converged a ton in recent years, so the differences in practice have grown much smaller. There are more dramatic differences in what you *could* do when designing a frame with various layouts, but people have kinda figured out that leverage curves that are pretty straight with some amount of progression, and anti-squat in the vicinity of 100% or a little higher at sag, falling off deeper in the travel works pretty damn well and most modern bikes end up being right along those lines.

  5. #5
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    Toast and HAB have it right. The important thing for stable climbing is the anti-squat number. For those who understand the VPP, anti-squat is sort of a virtual pivot built from a virtual pivot.

    With no front derailleur, the only appreciable difference between the various types (add single pivot to the list, it can work pretty well, too) is how well they maintain their AS number when squat changes, when pointed up hill, etc. Some designs can be dialed in to rider weight/COM height a little more by changing sag, but they will tend to be more sensative to sag so maybe more fiddly to own.

    Changes to the AS number outside the region where you'll be pedaling aren't really about squat anymore, so different wheel rates can be achieved in different ways mid/late in the travel--two bikes can each work fine and even feel similar without having similar AS numbers after ~40% travel.

  6. #6
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    https://www.pinkbike.com/news/behind...eti-sb140.html

    way more than you wana read ^^ about the engineering of the Yeti switch infinity, I like it and i almost never lock it out

    I had a Giant NRS (No Resonance System )which was a horst link with < 4" of travel and i really that system for an xc bike, it felt just like a hard tail until you hit something

    I guess I have had single pivot/horst/switch infinity



    edit: if yer an enginerd that ^^ link has about 6 pages of nerding, talks about DW, talks about the ripmo, has dynamic models, sez yeti is just a 4 bar with one infintely loooong link
    Last edited by XXX-er; 06-30-2020 at 12:04 PM.
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  7. #7
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    Good point by jono that the death of the front derailleur helped a lot. Having the line of action of the chain moving across multiple chainrings made balancing pedaling characteristics way harder, and lead to some compromises there. Not having to worry about that anymore simplifies things a lot.

  8. #8
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    The front der made for compromises in the chain stay/BB area
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  9. #9
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    Been on DW-link for 10 yrs now and like it. Prior to buying my current bike I test rode a ton of different designs. None were terrible.

    A few were ok but not great (Yeti, some Santa Cruz). The ones I liked best were Turner Flux (DW link) and Intense Primer (VPP w modified link). Ended up getting a too good to pass up deal on Mojo 3. Which is good since I don't think I'm Bro-core cool enough to ride an Intense. And Turner seems to have gone out of business.

  10. #10
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    Outside of hardtails, traditional single pivots, and weird one/off designs; I tend to overgeneralize the remaining designs into two categories:

    - Modified / linkage single pivots w/ multi-piece rear triangles - Most brands; Specialized, Trek, Transition, Devinchi etc. Typically more active. Typically cheaper.

    - Single-piece rear triangle with two mini links / four bar - Yeti, Santa Cruz, Ibis. Typically better pedaling. Typically more expensive.
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  11. #11
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  12. #12
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    If you're skilled, you feed the horse

  13. #13
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    Since it's a dead horse thread, here's more detail than anyone wants (TL/DR: since COM height varies with riders, YRMV.)

    I ran a bunch of simulations a few years back and found 3 resonance inducers in pedaling: weight transfer, chain tension, and leg inertia/COM movement. The first two can be mostly balanced against each other (DW seems to like doing that), although it's marginally easier/more effective to zero them independently by pointing the chain at the pivot point (virtual or otherwise) so the chain makes no torque around the pivot (that way gear ratio falls out, apart from any impact from changing the chain line, which can usually be minimized, too). Then point the line from the rear tire contact patch through the pivot to a point at the height of the COM over the front wheel. This ensures that forward acceleration pushes directly toward the pivot so that the weight transfer under acceleration passes through the rigid suspension members instead of compressing the spring. (The proof for that in my head uses the calculus definition of work, which seems like a shitty explanation of it but I'll share a simplified version if anyone cares. It's also akin to roll center heights in cars if that helps.)

    That leaves the legs' motion, and unfortunately the legs' mass moves around slightly out of phase with the change in crank torque. Fortunately, that effect is small, since there isn't much of anything that can be done to cancel it with the other two due to the phase difference. I looked into that, but found that raising or lowering anti-squat always increased bobbing in the simulations I ran (sims have the advantage of knowing the precise COM location, sag etc. so you can measure the effects of very small changes).

    Specialized made a lot of bikes with lots of bob. Some others copied them. Doing it wrong has been held against the Horst link ever since but, for example, the counter-rotating variety (little short/vertical link above the crank and long chainstays) can offer a stable 100% AS arrangement which pedals very well when done right. Move the pivots a little and anything can suck. And since COM height varies with riders, YRMV, and since nothing is perfect, even for one rider, the minor deficiencies of one design or another are easily overlooked if AS is kept close to 100%.

  14. #14
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    Quote Originally Posted by evdog View Post
    Been on DW-link for 10 yrs now and like it. Prior to buying my current bike I test rode a ton of different designs. None were terrible.

    A few were ok but not great (Yeti, some Santa Cruz). The ones I liked best were Turner Flux (DW link) and Intense Primer (VPP w modified link). Ended up getting a too good to pass up deal on Mojo 3. Which is good since I don't think I'm Bro-core cool enough to ride an Intense. And Turner seems to have gone out of business.
    I must be uber Bro-core cool then. Awesome.

    I've got an Intense Spider, and have demoed a number of SC bikes. The ride qualities for the two VPP brands have seemed remarkably different to me, with the SC having a much more planted feel and the Intense a lively poppy feel. Or dead and fun.

  15. #15
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    Quote Originally Posted by panchosdad View Post
    I must be uber Bro-core cool then. Awesome.
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  16. #16
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    Any thoughts on which design requires less maintenance or places less stress at the pivots? My 2 Santa Cruz’s lower bearings last about 3/4 to 1 season before they need re-grease or replacement whereas my old Ibis could make it a whole season or 1 1/2. My wife’s Pivot seems similarly durable but she’s light.

  17. #17
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    Quote Originally Posted by Mr. Toad View Post
    Any thoughts on which design requires less maintenance or places less stress at the pivots? My 2 Santa Cruz’s lower bearings last about 3/4 to 1 season before they need re-grease or replacement whereas my old Ibis could make it a whole season or 1 1/2. My wife’s Pivot seems similarly durable but she’s light.
    ETA: the right answer here is single pivot. The rest of this post mostly assumes you have selected a less right answer.

    Every design requires specific engineering to size the bearings and links appropriately. There are pros and cons to each type, but the thing you're most likely to notice in bearing life is how much margin that specific bike had. Of those pros and cons, the bigger issues probably relate to torsional stiffness, rather than kinematics. I'll admit to a small bias against the dual short link setups for that reason, but they can still be done right.

    It's kind of like how the bike feels overall: getting the spring and shock rates right is way more obvious than the relatively subtle kinematic differences, except when someone makes a mistake. The subtle differences stand out more when pedaling, and to an even lesser degree under braking. Otherwise wheel rate is more important and that's almost completely independent of your 4-bar's name.

  18. #18
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    Quote Originally Posted by Mr. Toad View Post
    Any thoughts on which design requires less maintenance or places less stress at the pivots? My 2 Santa Cruz’s lower bearings last about 3/4 to 1 season before they need re-grease or replacement whereas my old Ibis could make it a whole season or 1 1/2. My wife’s Pivot seems similarly durable but she’s light.
    I thought Santa Cruz offered a lifetime bearing warranty - but I guess it's still annoying to have to keep replacing them.

    My friend's Intense Primer (I think - not 100% on the model) has grease zerks in the lower link. I like that idea, no idea how well it works.
    Quote Originally Posted by powder11 View Post
    if you have to resort to taking advice from the nitwits on this forum, then you're doomed.

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