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  1. #1
    jddist
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    Chain growth question for MR. DW

    Was wondering what amount of chain length growth the 5 spot has compared to the Firebird, less, same, or more? I ask because I have had a Firebird and a single pivot Yeti 7 for a year trying to figure out which one I liked more. As usual there are things I like and dislike about both. The main issue I have with the Firebird is that even though it feels very efficient while pedaling, due to the anti-squat thing going on, by the end of a ride it feels less efficient. By this I mean that my legs are toast after a ride on the bird compared to how they feel after the same ride on my single pivot 7. I really noticed this after riding the bird for 3 month straight, at which point I had to start taking an extra day or 2 off between rides to let my legs recover. Then i picked up a 7, and on the first ride on the same trail the bike felt 10 lbs lighter and at the end of the ride my legs felt great. Switched to the 7 for 2 months and no more leg problems. I attribute this to the large amount of chain growth, and therefor pedal kickback, the bird has when climbing in granny gear, which is half my ride. When slow pedaling over stuff that activates the rear end, the chain growth kicks back into the legs on each stroke requiring more leg energy. Yes, granted less pedal bob is the result, but at the expense of more leg energy required to achieve this. Basic physics at play here I think. I do however really like the braking and ride characteristics of the bird when going at speed, and was wondering if the spot might have less chain growth and therefore less pedal feedback. Thank for any feedback anyone might have.

  2. #2
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    Well, I have never heard that chain tension would cause so much more effort as to be tiring. On my dw spot, I can feel the tension while in the granny and actually have come to the opposite conclusion. I am actually less tired and my legs are less worn out after a ride on the dw spot than on my old ML. And I am in worse shape.

    Set up maybe? The dw link is an odd thing. I had put on a shorter stem and ran it really low to aid in climbing. Bike felt slow like this. Ran the stem high with most of the spacers underneath and the bike feels much better. On steep climbs the dw link seems to like, heck even require, the weight shift that stiffens the rear and really aids in climbing. You can have your front end work with you on the descents and on the climbs. Pretty nice if you ask me.

  3. #3
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    I used to be pretty obsessed with pedaling efficiency, always busied my mind with analyzing which suspension system would give a good balance between "pedaling efficiency" and "being active under braking", because like most guys doing MTB, I want to get up the mountain using the minimal amount of energy while still having an active rear end for the down. Read a bunch about single pivot, FSR, DW, bobbing, chain growth, platform, etc... Well all this analysis has now really become secondary in my mind due to much much improved leg stamina from 4 months of intense road riding! So what I'm saying is, train your legs, and you'll be able to ride pretty mucy any "all mountain" bike making your buddies look like snail, and you wouldn't be asking this!

  4. #4
    jddist
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    Yea, that is what I was thinking, but in reality, either due to age or medical issues or both, making those gains just has not materialized. These days I am happy to just be maintaining my current level of stamina, and need to take advantage of every little "trick in the book" I can find. It's not that I am hung on over analyzing all the bike tech out there, just looking at my personal experience and adding some logic to it.

  5. #5
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    Quote Originally Posted by istvisinet View Post
    Was wondering what amount of chain length growth the 5 spot has compared to the Firebird, less, same, or more? I ask because I have had a Firebird and a single pivot Yeti 7 for a year trying to figure out which one I liked more. As usual there are things I like and dislike about both. The main issue I have with the Firebird is that even though it feels very efficient while pedaling, due to the anti-squat thing going on, by the end of a ride it feels less efficient. By this I mean that my legs are toast after a ride on the bird compared to how they feel after the same ride on my single pivot 7. I really noticed this after riding the bird for 3 month straight, at which point I had to start taking an extra day or 2 off between rides to let my legs recover. Then i picked up a 7, and on the first ride on the same trail the bike felt 10 lbs lighter and at the end of the ride my legs felt great. Switched to the 7 for 2 months and no more leg problems. I attribute this to the large amount of chain growth, and therefor pedal kickback, the bird has when climbing in granny gear, which is half my ride. When slow pedaling over stuff that activates the rear end, the chain growth kicks back into the legs on each stroke requiring more leg energy. Yes, granted less pedal bob is the result, but at the expense of more leg energy required to achieve this. Basic physics at play here I think. I do however really like the braking and ride characteristics of the bird when going at speed, and was wondering if the spot might have less chain growth and therefore less pedal feedback. Thank for any feedback anyone might have.
    More than likely its a fit issue. Take measurements of the two bikes and find out if the seat is in the same place relative to the BB, handlebars, etc.
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  6. #6
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    Quote Originally Posted by chauzie View Post
    I used to be pretty obsessed with pedaling efficiency, always busied my mind with analyzing which suspension system would give a good balance between "pedaling efficiency" and "being active under braking", because like most guys doing MTB, I want to get up the mountain using the minimal amount of energy while still having an active rear end for the down. Read a bunch about single pivot, FSR, DW, bobbing, chain growth, platform, etc... Well all this analysis has now really become secondary in my mind due to much much improved leg stamina from 4 months of intense road riding! So what I'm saying is, train your legs, and you'll be able to ride pretty mucy any "all mountain" bike making your buddies look like snail, and you wouldn't be asking this!
    Yup. Road riding teaches you how to pedal. After spending some time on the road, you will be able to ride lots of different types of suspension bikes without having to worry about bob.

  7. #7
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    ^ yup.

    key thing in pedaling efficiency is to spin in granny gear, or if your leg can take it, spin in the middle ring. Spinning creates very minimal bob, because you're not so much pounding down on the pedals as you're using technique and leg muscle memory to turn over the cranks. FSR, DW, VPP, all work equally well under spinning.

    But admittedly, to get strong legs do require serious road training. But even 1-2 days per week spinning your mtb bike on the road will help out the legs tremendously. I know a guy almost 70 yr old who has been riding mtb for a while, and being close to 70 he thought this is all the stamina he's gonna see. Boy was he wrong. After he did serious road training with me, the young MTB bucks in their 20s and 30s are working hard to stay with him. So don't let age get you thinking "oh i'm old, i can't improve". Never.

  8. #8
    jddist
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    Thanks for all the advise, I will seriously take it into account and try your suggestions. One thing I think I need to clarify is that I am not really talking about general pedal bob as an issue. General granny gear pedaling/spinning, such as steep smooth trail or fire road conditions, is great. I don't have a problem with the slight pedal feedback in these conditions. What I am talking about is when you are climbing up steep technical stuff where there are 1 and 2 foot + step-ups all over the place where you can't just sit and spin. In these cases the rear will compress significantly, there is just no way around that, and when a bike has significant chain growth all that growth gets kicked back directly into the legs requiring significantly more force at that instant. So much so that if the legs are already a bit tired and you have to power up a steep steep rock section, the bike can stall on you at that instant due to all that extra force/power required at that instant. The exact problem of pedaling a longer travel bike with a high front pivot location up anything. On my 7 this is not an issue, same trails same everything. My thought is that if the spot has less chain growth than the bird it may work better for me. A bit less rear end travel would be an easy trade off if I can get rid of this one issue.

  9. #9
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    Quote Originally Posted by istvisinet View Post
    Thanks for all the advise, I will seriously take it into account and try your suggestions. One thing I think I need to clarify is that I am not really talking about general pedal bob as an issue. General granny gear pedaling/spinning, such as steep smooth trail or fire road conditions, is great. I don't have a problem with the slight pedal feedback in these conditions. What I am talking about is when you are climbing up steep technical stuff where there are 1 and 2 foot + step-ups all over the place where you can't just sit and spin. In these cases the rear will compress significantly, there is just no way around that, and when a bike has significant chain growth all that growth gets kicked back directly into the legs requiring significantly more force at that instant. So much so that if the legs are already a bit tired and you have to power up a steep steep rock section, the bike can stall on you at that instant due to all that extra force/power required at that instant. The exact problem of pedaling a longer travel bike with a high front pivot location up anything. On my 7 this is not an issue, same trails same everything. My thought is that if the spot has less chain growth than the bird it may work better for me. A bit less rear end travel would be an easy trade off if I can get rid of this one issue.
    I have experienced exactly what you described on your Bird, on my DW-Spot.

  10. #10
    Daniel the Dog
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    I doubt it is design but probably fit as mentioned.

    I hear singlespeeding really helps one learn how to use their body and pedal stroke more efficiently.

  11. #11
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    Quote Originally Posted by AndyN View Post
    I have experienced exactly what you described on your Bird, on my DW-Spot.
    I think this is one area where DW may not be as good as other, lower antisquat bikes.
    Stupid, but sometimes witty. Occasionally brilliant. Slow and fat though.

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  12. #12
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    Here is a little comparison in Linkage looking at chain extension and pedal feedback in the granny gear for the Pivot Firebird, Turner 5 Spot, and the prototype Knolly Chilcotin.

    Now, I know that _dw says that every time someone runs a Linkage model calculation a baby seal gets clubbed, but here is what I find curious and interesting in this particular analysis. If you compare the Spot and the Firebird, two completely independent models for different bikes designed by different manufacturers (presumably with totally uncorrelated errors in the translation of the linkage geometry to the model) almost match the chain extension perfectly throughout the travel range. This seems to hint at a design characteristic that _dw aims for in his suspension platform.

    As a comparison, I plotted also the prototype Knolly Chilcotin chain extension (4x4 suspension) to show an example of a more neutral design. Of course, the more neutral platform will squat more under acceleration and hard pedaling, so pick your poison and find which trade-off works best for you and the terrain where you ride.



    Last edited by nybike1971; 12-10-2011 at 10:27 AM.

  13. #13
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    It seems that with an adjustable link between the chain and seat stay one could tune chain growth to one's liking.

  14. #14
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    While I only have a few rides on the bird, I do own a dw and have ridden several vp and dw esque bikes with noticeable pedal feedback. Let me let you in on a little secret, there is a simple way to overcome it..... run a larger front granny. Try a minimum of a 26tooth or a 28 tooth or even better a 32tooth front granny. Problem solved, you will get less bob, and better suspension action under pedaling load to boot. If you can't handle that big of a granny run a 36 tooth rear cog which will offset the bigger granny.

  15. #15
    jddist
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    WOW! All great information, especially from NYBIKE. Thanks a bunch. I have thought about increasing granny ring from 22 to 24 and the cassette from a 34 to a 36 to offset this and still have the same gearing. Big JC, have you done this? Don't want to change the overall granny gearing because I use this all the time on every ride but changing front and back might solve some of this. Thanks

  16. #16
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    Quote Originally Posted by istvisinet View Post
    WOW! All great information, especially from NYBIKE. Thanks a bunch. I have thought about increasing granny ring from 22 to 24 and the cassette from a 34 to a 36 to offset this and still have the same gearing. Big JC, have you done this? Don't want to change the overall granny gearing because I use this all the time on every ride but changing front and back might solve some of this. Thanks
    Yeah mang, me and countless upon countless others run bigger grannies to get rid of the feedback. 24t front will definately help and may get rid of it. If not try a 26t which seems to be the consensus where people can no longer feel it at all (bike dependent),.You will be surprised how much a 36 tooth cog can offset a larger granny. Lots of 36t cassettes on the market now, give it a try. I switched to a 2 ring front set up many years ago and never missed triple chainrings then switched to a single 32 front ring which took at least a season to get used to but now love it and feel it has made me a better rider, especially on steep punchy climbs.
    Last edited by WHALENARD; 12-10-2011 at 02:52 PM.

  17. #17
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    I agree that running a bigger chain-ring will lessen anti-squat, and DW has confirmed this.
    But doesn't anti-squat increase as rear cog size increases? Making the use of a larger granny ring with larger cog a wash?

  18. #18
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    Quote Originally Posted by AndyN View Post
    I agree that running a bigger chain-ring will lessen anti-squat, and DW has confirmed this.
    But doesn't anti-squat increase as rear cog size increases? Making the use of a larger granny ring with larger cog a wash?
    Nope, with a larger granny and larger rear cog the anti-squat and the kickback is going to get smaller. The only problem here is how fit is the OP, because not everyone can run a 26-36...

  19. #19
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    Quote Originally Posted by Vrock View Post
    Nope, with a larger granny and larger rear cog the anti-squat and the kickback is going to get smaller.
    Are you suggesting the chain angle off horizon has nothing to do with anti-squat?

    Not saying you're wrong, but, numbers please.

  20. #20
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    Quote Originally Posted by AndyN View Post
    Are you suggesting the chain angle off horizon has nothing to do with anti-squat?

    Not saying you're wrong, but, numbers please.
    I have crunched the Linkage analysis for 22/30, 22/36, and 26/36 (very close gear ratio to 22/30) on the Firebird and the pedal feedback charts at zero front travel are shown below.

    You can read about the pedal feedback calculation here, but in essence there are several factors contributing to pedal feedback as the suspension cycles and the total amount depends in principle on both the front and rear gears. While it is true as you say that the bigger rear cog to preserve gear ratio will negate some of the benefit of the bigger chainring, the effect of the bigger chainring dominates and the two don't balance each other out exactly.

    Basically, the angle of the chain affects the overall pedal feedback to a lesser degree than the backward rotation of the cranks to account for the chain length change between cogwheels' upper contact points. While the chain extension (measured in mm) is essentially independent of the gearing, the feeling of the extension at the cranks is given by the ratio of the extension itself to the radius of the front chainring (bigger front chainring, less feedback).






  21. #21
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    Quote Originally Posted by nybike1971 View Post
    there are several factors contributing to pedal feedback as the suspension cycles and the total amount depends in principle on both the front and rear gears. While it is true as you say that the bigger rear cog to preserve gear ratio will negate some of the benefit of the bigger chainring, the effect of the bigger chainring dominates and the two don't balance each other out exactly.
    This is essentially the point I was trying to make. Feedback/anti-squat can be mitigated to a minor degree using non-conventional gearing, but not eliminated.

    Thanks for the detailed explanation.

  22. #22
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    Quote Originally Posted by AndyN View Post
    This is essentially the point I was trying to make. Feedback/anti-squat can be mitigated to a minor degree using non-conventional gearing, but not eliminated.

    Thanks for the detailed explanation.
    Graphs and ratios are great but there is also an aspect to science called "in the field". Take an actual bike on an actual trail and run an increasingly larger ring until the feedback is imperceptible. There is another force at work here that I don't think has been covered. The bigger the ring the further the chain is away from your bb axle thus the less force it can exert on it, and the less distance it would travel backwards (feedback).

  23. #23
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    Quote Originally Posted by big JC View Post
    Graphs and ratios are great but there is also an aspect to science called "in the field". Take an actual bike on an actual trail and run an increasingly larger ring until the feedback is imperceptible. There is another force at work here that I don't think has been covered. The bigger the ring the further the chain is away from your bb axle thus the less force it can exert on it, and the less distance it would travel backwards (feedback).
    I rode a DW Spot for 2 1/2 years "in the field". Feedback was always perceptible, even in the 32t middle ring.

  24. #24
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    Quote Originally Posted by AndyN View Post
    I rode a DW Spot for 2 1/2 years "in the field". Feedback was always perceptible, even in the 32t middle ring.
    Wellllllll..... I guess perception is certainly subjective, especially if you have a completely neutral hl bike in your stable. My experience has been that around a 28t granny it's all but gone

  25. #25
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    Quote Originally Posted by AndyN View Post
    I rode a DW Spot for 2 1/2 years "in the field". Feedback was always perceptible, even in the 32t middle ring.
    That's impossible. You were riding it wrong, had it set up wrong, or were in the wrong terrain.

  26. #26
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    Quote Originally Posted by big JC View Post
    Wellllllll..... I guess perception is certainly subjective, especially if you have a completely neutral hl bike in your stable. My experience has been that around a 28t granny it's all but gone
    Yeah, subjective for sure. My knees are pretty sensitive, and I have a neutral bike in the stable.

    YMMV

  27. #27
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    Is the dw anti-squat magic determined by the the amount of teeth engaged by the chain under load (sorry, I'm a newb)?

    If not, may I ask what other drivetrain factors might affect dw-link performance?

    Such as:

    Does the addition of a chainguide/tensioning system affect it?

    How about different derailleur cage lengths?

    Links in a chain?

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