• 02-09-2013
    DirtyMartini
    Suspension design, climbing, and BB height
    What modern frame designs use pedaling forces to help hold the rear suspension in the upper end of it's travel?

    I'm looking for my next AM/FR bike, I "like" to climb, but only for the sake of descending. I'm much more concerned geometry and a higher BB height when climbing than optimum pedaling efficiency. I don't mind accepting some pedal bob it means avoiding some pedal strikes when climbing the rocky sections.
  • 02-09-2013
    keen
    I think you have contradicted yourself a bit. if you don't want the rear squat you will need a suspension design that does not pedal bob. pedal bob is shock compression which equals a lower rear suspension. DW link should get you what you want.
  • 02-09-2013
    DirtyMartini
    I think most examples of "bob" are compression bob, but I think there are examples of extension bob. Here's an excerpt from Canfields site:

    "The main idea with Parallel link suspension is in setting up the chain line with virtual pivot under sag. The problems start when you run more than one chainring in the front using a front derailleur. When you shift from one chainring (like the 22t to the 32t) you change your chain-line height over an inch. We found that when most frames are designed around a 32t chainring and the frame is in the 22t, the suspension is overloaded by the extra low chain-line to virtual pivot. This pulls the suspension to the top of itís travel causing an inchworm effect under each pedal stroke."

    I'm assuming "inchworm effect" is referring to top of travel bob.

    Regardless, the DW link tries to isolate reward acceleration forces (that occur from pedaling) from the suspension. While this helps keep the suspension supple while pedaling and you don't waste energy compressing the shock by pedaling, pedaling doesn't pull the linkage in a way that raises the BB above the sag height DW link attempt to maintain the BB at the sag height while pedaling. I'm wondering if there's a system that raises the BB height above sag when pedaling.
  • 02-10-2013
    fsrxc
    Some Santa Cruz VPP bikes?
  • 02-10-2013
    Fuglio
    Quote:

    Originally Posted by DirtyMartini View Post
    I think most examples of "bob" are compression bob, but I think there are examples of extension bob. Here's an excerpt from Canfields site:

    "The main idea with Parallel link suspension is in setting up the chain line with virtual pivot under sag. The problems start when you run more than one chainring in the front using a front derailleur. When you shift from one chainring (like the 22t to the 32t) you change your chain-line height over an inch. We found that when most frames are designed around a 32t chainring and the frame is in the 22t, the suspension is overloaded by the extra low chain-line to virtual pivot. This pulls the suspension to the top of itís travel causing an inchworm effect under each pedal stroke."

    I'm assuming "inchworm effect" is referring to top of travel bob.

    Regardless, the DW link tries to isolate reward acceleration forces (that occur from pedaling) from the suspension. While this helps keep the suspension supple while pedaling and you don't waste energy compressing the shock by pedaling, pedaling doesn't pull the linkage in a way that raises the BB above the sag height DW link attempt to maintain the BB at the sag height while pedaling. I'm wondering if there's a system that raises the BB height above sag when pedaling.

    are you looking for justification to buy a bike you all ready decided you wanted?... just get the canfeild ONE it looks bad ass
  • 02-10-2013
    DirtyMartini
    Quote:

    Originally Posted by Fuglio View Post
    are you looking for justification to buy a bike you all ready decided you wanted?... just get the canfeild ONE it looks bad ass

    Oh no, not at all. My buddy just got a canfield ONE and it peaked my interest. I like long top tube bikes and it's one of the few AM/FR bikes that are made with a 17.5-18" reach. When my current bike (kona coilair) does a great job climbing because the magic link keeps a high BB when pedaling. However, I"m not really settling in the the bike on the DH, something just keeps feeling..."off"

    Anyway, I like the high BB when pedaling feature compared to my old old bike (Iron Horse 6 Point), which descended great but pedal strikes where a pain. I'm trying to find something with a more "standard" rear suspension setup (not magic link), but that has a high BB when pedaling feature.
  • 02-10-2013
    fracaxis
    I think you might want to start looking for something with a high pivot such as the old santa cruz bullets, Orange, Morewood. The higher pivot lines up with a bigger ring when descending and be relatively neutral or active. Then when climbing and dropping into the granny ring the chain pull would counteract some of the suspension action and keep the BB more where you like it.