[saruti]

hi guys

after demoing a bike few months a go, I found out that zero kickback is really great when riding a bike.
I want to make an idler pulley for my current bike.
the question is, how can I find the place for the idler pulley?
is it just by tying? or is there a way to know exactly where to place it?

thanks

 

[Flo33]

It's not that easy. It depends on the kinematics of rear sus (and the retaining force of your clutch rear derailleur).

E.g. on a high single pivot you would want two chains, one from your crankset to the pivot and another one from the pivot to your rear wheel if you rally want zero kickback in all situations.

 

[jonKranked]

It's not that easy. It depends on the kinematics of rear sus (and the retaining force of your clutch rear derailleur).

E.g. on a high single pivot you would want two chains, one from your crankset to the pivot and another one from the pivot to your rear wheel if you rally want zero kickback in all situations.

 

[saruti]

thanks fFo33. I know all that.
I asked maybe someone know a way of figuring that without too much work. an app or something.

 

[Sandwich]

check with Corsair, they used idlers.

 

[buckoW]

What pulley are you planning on using? How are you going to mount it?
The clearance needed between your chainring and idler pulley wheel will define your chainline and put it too high. You'll end up with very little antisquat so the bike will pedal like a wet pillow. What frame are you looking to do this on? If your mainpivot is above your chainline you might have a chance otherwise you'll have to run a very small chainring to create the clearance.

 

[Flo33]

Me want moar chainz!

 

[SkaredShtles]

I thought that was what SRAM gold links were for?

 

[TrumbullHucker]

first thing that came to mind

seems to be welded to the swingarm though, i think

google " blenki idler "

 

[saruti]

i think of maybe connect it to the ISCG with aluminium plate
the bike is SB6c YETI

 

[slimshady]

An idler pulley on a virtual pivot system like the one on the Yetis would be a very bad idea, unless properly executed, like Canfield used to do. And for that to happen, you would have to attach the idler to one of the links, which would be unnecessarily complicated in the Yeti.

 

[HAB]

An idler pulley on a virtual pivot system like the one on the Yetis would be a very bad idea, unless properly executed, like Canfield used to do. And for that to happen, you would have to attach the idler to one of the links, which would be unnecessarily complicated in the Yeti.

Well, with the Yeti, it's actually easy to keep track of where the instant center is, because it's just at the pivot on the slidey bit. But yeah, it's way too low for an idler to work well. As @buckoW said, by the time you've gotten an idler on that bike, it'll have to be up above the chainring, and therefore way above the instant center anywhere in the travel, and therefore pedal like shit.

 

[dcamp29]

Whatever you do- make sure the pulley is mounted really solid. I've had a few home-made idler things and unless they are super solid the chain torque will flex and it feels 'soft' when you're pedaling. And bigger idler=better. Small idlers feel grindy.

 

[hmcleay]

hi guys

after demoing a bike few months a go, I found out that zero kickback is really great when riding a bike.
I want to make an idler pulley for my current bike.
the question is, how can I find the place for the idler pulley?
is it just by tying? or is there a way to know exactly where to place it?

thanks

If you want exactly zero chain growth, then the chainline needs to be parallel to the Axle-IC line.
For a single pivot bike, the simplest way would be to mount an idler on the pivot, and size it the same as the middle cog in your cassette. This will give zero chain growth throughout the entire range of travel, but only for that one gear in your cassette.

As pointed out by BuckoW, it's unlikely you'll physically be able to achieve this unless your bike has a very rearward axle path (by 'conventional drivetrain' standards).
What bike are you planning on doing this to? And what bike did you demo that made you think zero kickback was a great thing?
If you create zero chain growth on a bike with a 'conventional' axle path (one that works with a conventional drivetrain), then you're going to end up with about zero Anti-Squat at sag, so it will pedal like shit.

EDIT:
I missed the bit where you already said it was a Yeti SB6c.
The IC on this bike only moves a short distance, which is roughly horizontally through the lower floating pivot. These posts have some more detail on that suspension configuration:
Ad infinitum from Yeti
Ad infinitum from Yeti



Hope that helps.
Cheers,
Hugh.

 

[saruti]

thanks @hmcleay
I demo a Focus Spine. and it was amazing. only 120mm of travel hat felt like much more.