Describe in simple terms how having an idler improves the bikes suspension/pedaling performance?
I thought I understood, but I now think I don’t.
I thought I understood, but I now think I don’t.
Can Any Of You Nerds...(Idler question)
- Thread starter rideit
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Using them allows for a suspension design with a more rearward axle path by mitigating the pedal kickback you'd get from excessive chain-growth without one.
I guess I am stumbling on how it ‘mitigates’.
Look at this thing and imagine if the idler wasn't there. With such a high pivot the distance between the chainring and the cassette would increase quite a bit as the suspension moves through its travel, resulting in a lot of chain growth and thus in a major tug on the pedals as the suspension compressed. When you add the idler, the change in distance between the cog and the cassette as the suspension moves through its travel is comparatively much less since the idler is placed at/near the main pivot.
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Thanks, that helps.
I‘ll Have to go on a really long ride and really mull this over, there are still a few unanswered questions.
i can visualize it, but not totally grasp the physics.
like I said, long ride time.
I‘ll Have to go on a really long ride and really mull this over, there are still a few unanswered questions.
i can visualize it, but not totally grasp the physics.
like I said, long ride time.
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are you...druid-curious?
No, but that did prompt the questions.
My (limited) understanding is that the idler pulley should be located so that...
1) the chain line is aimed directly into the pivot point such that chain tension won't cause any rotational moment/torque around the pivot point, eliminating/minimizing pedaling-induced suspension bob. Moment = force x distance = 0 if the distance is 0.
2) top side of the chain swings around the same point as (or very close proximity of) the suspension pivot. The chain links wrapped around the cassette follow the same arc/path as the cassette, minimizing chain growth and kickback.
Not sure how it's supposed to work on Horst/idler combos found on GT and Norco Shore. I guess they aim the chain line to the instant center at sag?
Idler location of 2021 Supreme Commie
1) the chain line is aimed directly into the pivot point such that chain tension won't cause any rotational moment/torque around the pivot point, eliminating/minimizing pedaling-induced suspension bob. Moment = force x distance = 0 if the distance is 0.
2) top side of the chain swings around the same point as (or very close proximity of) the suspension pivot. The chain links wrapped around the cassette follow the same arc/path as the cassette, minimizing chain growth and kickback.
Not sure how it's supposed to work on Horst/idler combos found on GT and Norco Shore. I guess they aim the chain line to the instant center at sag?
Idler location of 2021 Supreme Commie
Another oversimplification: The further the pivot point gets away from the top of the chain ring/chain line, the more pedaling and bump forces will result in the chain pulling on the suspension one way or another. However, some people really like suspension designs with a high pivot (mostly for the slightly rearward axle path), which by design requires the pivot to be pretty far from the chain line. To get what they think is the best of both worlds, they essentially separate things by moving the chain line up to the pivot using an idler. Opinions vary on how great it is and whether it's worth the trouble, weight, complexity, etc., but that's the idea.
What's its antisplat curve like?
chain far from pivot, pull
chain no far from pivot, no pull
idley make chain no far from pivot. no pull
chain no far from pivot, no pull
idley make chain no far from pivot. no pull
THOSE were the layman’s terms that I was looking for!
well done!
well done!
