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Discussion Starter · #1 ·
I was working on the DW Spot today and noticed something strange. With the rear shock removed I lifted the year tire to feel the smoothness of bushings, as I cycled through the travel I could see the cranks turning backwards. With each cycle of the swingarm the cranks would rotate. Holding the cranks I feel the suspention "lock-up". I can now recall going down some trails and feeling this peddal lock so to speak. So, is the DW not fully active or is my chain too short??? I don't remember this on my Horst or TNT Spot. Maybe I just never noticed it:skep:
 

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Stray Bullet
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Any time the chainstay length grows there will be pedal kick back. By your definition of 'fully active' the only suspension that will completely neutral is one with a pivot around the bottom bracket.
 

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Elitest thrill junkie
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Theoretically, yes. There is "100% anti-squat" designed into the bike when you have a normal amount of sag, as the suspension compresses this number decreases, as it's assumed the reason the suspension is compressing is due to bumps, but at that 100% level it also means that when pedaling, there is only enough anti-squat (hence 100% and not something more than 100%) to counteract the acceleration forces caused by pedaling. That means that if a bump comes along there is no force opposing the bump. If you are not pedaling there should also not be any sigificant forces opposing the bump.

This is in contrast to higher-pivot bikes that essentially have a lot more than 100% anti-squat. They pedal fine at times, but if you hit bumps you get a whole lot of interaction between the pedaling and suspension, making the suspension much less effective under power. Again, if you are just coasting it's not a big problem, but suspension that tends to "lock out" or at least "stiffen" when you pedal is not helping you maintain traction much. They can reduce the bob, but at the cost of reducing the overall suspension effectiveness and absorbing bumps during power. This is what DW achieves over high pivot bikes.
 

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Crazed Country Rebel
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Guitarzan415 said:
I was working on the DW Spot today and noticed something strange. With the rear shock removed I lifted the year tire to feel the smoothness of bushings, as I cycled through the travel I could see the cranks turning backwards. With each cycle of the swingarm the cranks would rotate. Holding the cranks I feel the suspention "lock-up". I can now recall going down some trails and feeling this peddal lock so to speak. So, is the DW not fully active or is my chain too short??? I don't remember this on my Horst or TNT Spot. Maybe I just never noticed it:skep:
Nothing is 100% fully active. All bikes have some feedback either from the drive train, braking or both.

DW's are very active though and seem to have a good balance of positive features with very few negatives.
 

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Discussion Starter · #9 ·
Figured it out.

Maybe,

I think the feedback I am experiencing is due to the rear derailer. It's the new Shimano shadow and these only rotate in the backwards direction. So when the suspension moves the chain shortens and with the "old style" derailers they rotate fwd/rwd thus giving a bit for the shortening of the chain....I think:thumbsup:
 

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Guitarzan415 said:
I was working on the DW Spot today and noticed something strange. With the rear shock removed I lifted the year tire to feel the smoothness of bushings, as I cycled through the travel I could see the cranks turning backwards. With each cycle of the swingarm the cranks would rotate. Holding the cranks I feel the suspention "lock-up". I can now recall going down some trails and feeling this peddal lock so to speak. So, is the DW not fully active or is my chain too short??? I don't remember this on my Horst or TNT Spot. Maybe I just never noticed it:skep:
This might help...or maybe not...
 

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Discussion Starter · #12 ·
Yep!

1niceride said:
This might help...or maybe not...
I totally see what the link is saying...I do think the rear derailer has alot to do with it. Look at the simulation and I think you will see that the RD does not move foreward in any of the comparisons, thus causing the padal feedback.
 

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Crazed Country Rebel
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Bikezilla said:
So GT minimizes pedal feedback by moving the pedals back and forth?

:eek:ut:
that's somewhat correct, but misleading. The idrive minimized pedal kickback/feedback by moving the bottom bracket towards the rear wheel as the suspension compresses.

Normally a bike will have a growing chainstay during compression. Too much chain growth creates pedal feedback.

The idrive reduces, but does not eliminate chain growth.

Some chain growth is good. Too much is no good.

You have to play with an idrive and take some measurements to realize how it works - becuase visually it appears the bb moves forward, when in fact it moves backwards.
 

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Lay off the Levers
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iheartbicycles said:
You have to play with an idrive and take some measurements to realize how it works - becuase visually it appears the bb moves forward, when in fact it moves backwards.
I'm just suggesting they are replacing (part) of an unwanted suspension element with another. Is a dynamically repositioned BB (and thus pedals) any less an issue as pedal feedback (given the same magnitude of movement/feedback) ?

Idon't know. I was being somewhat sarcastic in my first post. But it seems it's a tradeoff.
 

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Crazed Country Rebel
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Bikezilla said:
I'm just suggesting they are replacing (part) of an unwanted suspension element with another. Is a dynamically repositioned BB (and thus pedals) any less an issue as pedal feedback (given the same magnitude of movement/feedback) ?

Idon't know. I was being somewhat sarcastic in my first post. But it seems it's a tradeoff.
It's not a black and white issue, though. A small amount of chain growth is imperceptable. A small amount of BB movement is imperceptable.

This is what makes the dw and the idrive systems work - the designers have a window to work within to fine tune suspension characteristics without creating unwanted side effects.
 

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I agree that some chain growth is ok, and some bottom bracket movement is ok, if the overall result is a bike that pedals as well as the new DW Flux that I am riding. I would certainly trade off pedal feedback, due to chain growth then I would tollerate a lot of pedal movement. Does anyone remember the old Klein Mantra's or similiar unified rear triangles that the bottom bracket bobbed around on as the suspension cycled? In my mind it was as real pain to have a continually changing saddle position....

Ryan.

iheartbicycles said:
It's not a black and white issue, though. A small amount of chain growth is imperceptable. A small amount of BB movement is imperceptable.

This is what makes the dw and the idrive systems work - the designers have a window to work within to fine tune suspension characteristics without creating unwanted side effects.
 
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