Chain Suck under torque in Granny Gear

[Deacon Patrick]

This isn’t happening when shifting, it’s new and happening when well established in gear with gear mostly happy (it makes some noise in lowest gear that it doesn’t in higher ones), cranking up a steep hill. Especially happens if I stand to peddle. All suggestions welcome.

Possible fixes would seem to be:

— remove, clean, lube chain (it’s been 18 months)

— monkey with front derailure adjustment. Help here appreciated. I’m over my head on that one.

— Other ideas?

With abandon,

Patrick

www.MindYourHeadCoop.org

www.OurHolyConception.org

[Steve Palincsar]

On 10/31/2013 06:35 PM, Deacon Patrick wrote:

This isn�t happening when shifting, it�s new and happening when well established in gear with gear mostly happy (it makes some noise in lowest gear that it doesn�t in higher ones), cranking up a steep hill. Especially happens if I stand to peddle. All suggestions welcome.

Possible fixes would seem to be:

� remove, clean, lube chain (it�s been 18 months)

� monkey with front derailure adjustment. Help here appreciated. I�m over my head on that one.

� Other ideas?

Bent chain ring tooth?

[Deacon Patrick]

"Bent chain ring tooth?"

Isn't that improbable on the granny?

With abandon,

Patrick

[Bill Lindsay]

Has it been 18 months on that chain?  It would be worth a measurement if it has been.  24 links should be exactly 12 inches.  Common rule of thumb is replace the chain every 2000miles

[hsmitham]

Deacon,

Ah yes replace chain...it's not expensive, you Scots. Grin

I've had chain suck once and it was my fault starting a climb as I waited too long to gear up and feather the front derailleur. I could imagine that though you geared up at an appropriate time that the chain wasn't fully engaged with said cog resulting in an alignment issue exacerbated at the trail end of the front derailleur pushing the chain down between chain stay and derailleur. 

~Hugh

On Thursday, October 31, 2013 3:35:22 PM UTC-7, Deacon Patrick wrote:

[Bill Lindsay]

Measure it before you replace it, though.  If it is horribly stretched, you may be replacing the entire drivetrain.  Chain + cogset + chainrings.  If the chain is horribly stretched and you only replace the chain, a new chain might be even worse.  Measure first to get a sneak preview.  

[Hugh Smitham]

Bill,

He needs to look at the chain ring teeth if they are sharp then he'll need to replace same goes for the cassette, my understanding is that the issue is throwing on a new chain with worn out chain rings and cassette teeth will result in poor shifting and destroy a perfectly good chain.

`Hugh

Best,

~Hugh

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[Deacon Patrick]

Scots are all about spending money in maintenance to save more money in breakage. This just started, so hopefully no drive train issues save the chain.

With abandon,

Patrick

[Edwin W]

I was having the worst ghost shifts with my 1x8 set up on my Sam. A good chain cleaning (1st in months) solved it. I used the PDW chain cleaning machine, but a stiff brush and cleaning fluid does the same.

Edwin "don't like to clean things much"

[Hugh Smitham]

Just funnin with ya Deacon...I'm from a long line from the Hebrides

Best,

~Hugh

[Deacon Patrick]

Absolutely, Hugh. Fun away! My ancestors are from the Argyle Peninsula, so just a few wee boat rides and portages away.

With abandon,

Patrick

[Joe Bernard]

Are you cross-chaining? You might be catching the chain on the front teeth sideways-like if the bend from the granny to the smaller rear cogs is too severe. I only use the granny in the 3-or-4 biggest/lowest-gear cogs.

On Thursday, October 31, 2013 3:35:22 PM UTC-7, Deacon Patrick wrote:

[ascpgh]

Deacon,

Wipe the chain enough to lay a ruler up to it, line the zero mark up on a pin center and see where the 12" mark hits relative the nearest pin. Sage advice is replace the chain if 1/16" stretch is detected. A field-expedient that is less precise is to pull the middle of the chain wrapped around your big chainring away from the teeth and see how far it goes; a little is fine, halfway off the tooth not so good, over a tooth is excessive.  This demonstration includes wear of chainring teeth and should be followed by more careful assessment. 

Wear beyond 1/16" eats chainrings and cassette cogs at a faster rate. At 1/8" stretch, the drivetrain degrades in finer functions in normal use and begin to misbehave like chain suck when "Just Riding Along" (term of art in bike repair).

If the chain is beyond the normal length between its pins, it doesn't lay well around the tooth profile of the chainrings. Wrapped around a granny gear, the stretched chain is forced into a smaller set of tooth gaps by riding a little bit high on each tooth provided you are really easing along on the pedals. The force generated by the granny ring sinks those links farther onto the non-matching teeth beyond being freely engaging. So as the chainring rotates from the top where it is pulling the run of chain off the cassette cog, it is creating a binding fit of the chain onto itself to the point of sticking to the ring until knocked off by your frame. 

Continued riding will erode the teeth of rings and cogs.

Andy Cheatham

Pittsburgh 

[Deacon Patrick]

Like you, Joe, I don't cross chain. I will use my four lowest gears in my granny gear, but generally only the bottom 2-3.

With abandon,

Patrick

[doc]

and if all else fails...http://n-gear.com/whatis.html

On Thursday, October 31, 2013 6:35:22 PM UTC-4, Deacon Patrick wrote:

[Patrick Moore]

I had this happen with distressing frequency on the Fargo when the chain was dirty. I installed a device to prevent chainsuck; forget the name.

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[Patrick Moore]

That's the one. It works.

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[Deacon Patrick]

Good call. In my case, my chain's been dirty for 17.7963 months before this started happening.

The plan is to get a new chain and see where I go from there.

With abandon,

Patrick

[Deacon Patrick]

Just got back from the LBS. Chain was "very stretched" and after replacing it and a test ride it needed the granny cog replaced. I'm about to head out and see how she does on the wee waterfall ride. Thanks for your expertise!

With abandon,

Patrick

[dougP]

Consider a stainless steel granny.  They last much longer than aluminum. 

dougP

[Deacon Patrick]

Great idea, Doug. For now, I got what they gave me, but next time...

With abandon,

Patrick

[Deacon Patrick]

Checked receipt. Steel to replace steel. I've got one steely-spined granny! Grin.

With abandon,

Patrick

[Deacon Patrick]

I got a grand chuckle out of the receipt labeling my bike as a "Hunq Apillar Cross." And when I asked about if a particular book was a good one for area trails, the owner said, "Well yeah, but that's for mountain biking." I said "That's what I do." "With that bike?" with a look of wild wonder that such a thing could be done. Being counter-cultural affords multiple opportunities for amusement. Grin.

With abandon,

Patrick

[Philip Williamson]

I think I consider you more "parallel-cultural" than "counter-cultural." 

Philip

www.biketinker.com

[Perry]

Surprised that the granny would need replacement without the cog set needing it as well. Cogs are usually the first to go with a stretched chain--especially the smaller ones.

• Perry