# position of chain & rear derailleur when in the small gears



## rockyroller (9 Dec 2020)

does this look too high up? is the chain way too long? shud I remove a link? or is it normal & just caught my eye & freaked me out?


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## Specialeyes (9 Dec 2020)

Well, technically it's not maxxed out.... I'd stick it in big-big and if the rear derailleur doesn't look overstretched, then take a link out


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## rockyroller (9 Dec 2020)

Specialeyes said:


> Well, technically it's not maxxed out.... I'd stick it in big-big and if the rear derailleur doesn't look overstretched, then take a link out


thank you. looks OK to me, how about you or others?


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## si_c (9 Dec 2020)

Looks a bit marginal to me - almost like it could do with a link taking out. The angle of the first photograph doesn't help - when in the small-small how much slack is there in the chain on the bottom?


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## Ajax Bay (9 Dec 2020)

I'd leave it as you have it (assume first image is small/small). The return section of the chain isn't touching the chain round the guide jockey wheel, is it? You could probably take a link (one inch) out but then it'd be pretty tight large/large.


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## rockyroller (9 Dec 2020)

si_c said:


> when in the small-small how much slack is there in the chain on the bottom?


thank you. not sure how to determine that. it doesn't "droop" if that's what you mean


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## rockyroller (9 Dec 2020)

Ajax Bay said:


> The return section of the chain isn't touching the chain round the guide jockey wheel, is it?


thank you. no but it's close


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## Joffey (9 Dec 2020)

It is borderline - maybe just don't ride in little - little if it can be helped.


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## rockyroller (10 Dec 2020)

Joffey said:


> It is borderline - maybe just don't ride in little - little if it can be helped.


thank you. I can do that, but

I only have trouble w/small in front & big in back when the chain is dirty. it gets sucked up & jammed against the chainstay, stopping me cold in my track. that really stinks on a standing climb. probably need a new chain & chainrings


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## weareHKR (10 Dec 2020)

I would suggest taking a link out personally. 
Not a direct answer to your question, but you're getting into the areas of extreme cross chaining, ie, small/small & large/large generally are not good combinations, this also can cause excessive wear on your drive chain. This doesn't mean you can never use those combinations but they're not ideal. 
It also depends on the chain line of the bike, how the front
rings line up with the back in a straight line.
You could possibly increase peddling resistance too due to the extremes of cross chaining! 
With a tripple or double chainrings I would suggest you can achieve nearly all the combinations of gears without actually 
cross chaining!


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## fossyant (10 Dec 2020)

I'd take a link out !


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## fossyant (10 Dec 2020)

And get rid of the wheel reflectors


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## rockyroller (10 Dec 2020)

thanks CC'ers. I just may do that before the next ride

think I'll keep the dorky reflectors tho cuz sometimes I ride the bike on a busy road to the woods at night, also across/thru a busy intersection


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## Ajax Bay (10 Dec 2020)

rockyroller said:


> I only have trouble w/small in front & big in back when the chain is dirty. it gets sucked up & jammed against the chainstay, stopping me cold in my track. that really stinks on a standing climb. probably need a new chain & chainrings


You have introduced new information (chain suck occasionally in lowest gear).
So 'yes' take a link out, provided the chain will still go large/large.
Replace the inner/small chain ring. The other ones should remain entirely suck-free. The chain only needs changing if its elongation is more than the rider's self-imposed threshold or it means it starts skating over one of the rear sprockets. A new chain will just increase chain-suck _ceteris paribus_.
Chain suck - I learnt this the hard way (knowing there's was a problem - new chain and suddenly suck) climbing east-west over Wrynose and Hardknott Passes.
This is a useful and comprehensible article: http://fagan.co.za/Bikes/Csuck/ (referenced from Sheldon Brown's site).
A mitigation I used (and actually have left it there) is a chunky ziptie round the right chainstay up where the chainstay joins the BB shell. The idea was that a chain about to suck would knock against the ziptie and 'un-suck'.


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## Once a Wheeler (10 Dec 2020)

My rule of thumb is to put the chain on the biggest front chainwheel and the biggest rear sprocket and then shorten it to the minimum length which the arrangement allows. The problem with going to the limits at the other end of the range is that when the chain whips around during gear changes it tends to chip and damage the chain stay.


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## rockyroller (10 Dec 2020)

Ajax Bay said:


> You have introduced new information (chain suck occasionally in lowest gear).


thank you, I'll look into changing just the small chain ring. I've been dealing with this for some time ( a year or two) & I'm been keeping out of the mud, because of it. I've had to stop & clean the drivetrain on a cpl trips, even go so far as this


View: https://youtu.be/JMdL6hTGATI


I've read about the ziptie thing but haven't tried it yet. I should. thanks for that link, it must be the only article on chain suck I haven't read


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## rockyroller (10 Dec 2020)

Once a Wheeler said:


> My rule of thumb is to put the chain on the biggest front chainwheel and the biggest rear sprocket and then shorten it to the minimum length which the arrangement allows. The problem with going to the limits at the other end of the range is that when the chain whips around during gear changes it tends to chip and damage the chain stay.


I don't understand "shorten it to the minimum length which the arrangement allows". when I was investigating last night, live w/ fellow CCers, I noticed when in big, big, the rear derailleur was in what looked like a vertical position, and easily moved forward if I tugged on the chain. I doubt you are suggesting shorten the chain until the rear derailleur can no longer accommodate any more tugging


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## itboffin (10 Dec 2020)

i'd take two full links out


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## rockyroller (10 Dec 2020)

Ajax Bay said:


> a chunky ziptie round the right chainstay up where the chainstay joins the BB shell


I've seen photos but not way up front at the BB. also, some photos show ppl leaving some of the ziptie tail & some others just have the nubs. suggestions about cutting the tail off?


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## Ajax Bay (10 Dec 2020)

I cut the tail off - it would interfere with normal running. This is on a road bike.
When the chain is running normally on the inner ring the ziptie on the chainstay is not in the way, but if the chain sucks it rises up to chainstay level and the ziptie's 'block' (where the ratchet/internal serrated surface is) tips the sucking chain and dislodges it from the teeth, and the tension/force provided by the rear mech spring overwhelms the force holding the chain on the ascending teeth. If it were more visible I'd share a photo, but it isn't.


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## rockyroller (11 Dec 2020)

Ajax Bay said:


> I cut the tail off


thank you. how many nubs? 1 or more?


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## Ajax Bay (11 Dec 2020)

See the tail? That's the bit I cut off. I cannot guess what 'nubs' is a typo for .


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## rockyroller (11 Dec 2020)

Ajax Bay said:


> See the tail? That's the bit I cut off. I cannot guess what 'nubs' is a typo for .


lol, the lock, that part you put a pic up of. the black bump that the chain strikes. but how many did you use? I've seen pics of ppl using 1,2,3 & even 4. I suppose if I'm really smart I could use just one, but barring that, I'd think 3 or 4 would be less precise but more likely to work


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## rockyroller (11 Dec 2020)

well, I got 1 big one on, real tight. when I push the chain up where it would get lodged, it strikes the zip tie lock


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## Ajax Bay (11 Dec 2020)

Spot on (I used a black one to keep it incognito, mind) and check its position regularly. But best sort out the cause of the chain suck: I commend careful reading of the link I offered.


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## Once a Wheeler (11 Dec 2020)

rockyroller said:


> I don't understand "shorten it to the minimum length which the arrangement allows". when I was investigating last night, live w/ fellow CCers, I noticed when in big, big, the rear derailleur was in what looked like a vertical position, and easily moved forward if I tugged on the chain. I doubt you are suggesting shorten the chain until the rear derailleur can no longer accommodate any more tugging


Missing from my post is a consideration of the derailleur in question. Your observation is absolutely right for most people's equipment and setup because nowadays the wrap-round rarely gets anywhere near its limits. In this case 'one or two links less' would be the advice as others have noted here. Some gears, though, are very mean with their wrap-round capacity and, for these, taking it to the limit in the big-big combination is the best one can do. Hours of fascinating comment on this and similar subjects on the following site, which you may well be familiar with: http://www.disraeligears.co.uk/Site/Home.html


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## T4tomo (11 Dec 2020)

rockyroller said:


> I don't understand "shorten it to the minimum length which the arrangement allows". when I was investigating last night, live w/ fellow CCers, I noticed when in big, big, the rear derailleur was in what looked like a vertical position, and easily moved forward if I tugged on the chain. I doubt you are suggesting shorten the chain until the rear derailleur can no longer accommodate any more tugging


I wouldn't go as far as no longer accommodating any movement, but pretty close to that. 
Reason being is that an overly slack rear D / slack chain tension can cause imprecise rear shifting, so a shorter chain will give you slicker shifting. (*)

hence in situations where its "should I take out a link or not?" I'd err on taking a link out.

(*) as this is cyclechat someone will no doubt tell me this is wrong , but the cycle mechanic who advised me of this knows his onions.


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## T4tomo (11 Dec 2020)

apparently I posted that in the future?? WTF?


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## rockyroller (11 Dec 2020)

T4tomo said:


> I wouldn't go as far as no longer accommodating any movement, but pretty close to that.
> Reason being is that an overly slack rear D / slack chain tension can cause imprecise rear shifting, so a shorter chain will give you slicker shifting. (*)
> hence in situations where its "should I take out a link or not?" I'd err on taking a link out.
> (*) as this is cyclechat someone will no doubt tell me this is wrong , but the cycle mechanic who advised me of this knows his onions.


oh OK, thank you. it shifts fine in front & rear


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## rockyroller (20 Dec 2020)

last ride out was fine, as usual. no chain suck but it was a dry ride. chain stayed clean. regardless, I had some free time Saturday morning so I took a cpl links out, especially after looking at other bikes online & that we have in the house. also watched several "chain sizing" videos. I could have used a different technique to size it but I opted to just remove 2 links. seems OK & the bike easily shifts into all combinations on the workstand. I did use a tip from 1 video, a short section of coat hanger, w/ bends in the ends to hold the chain in place while I worked on it. also ordered a new chain


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## Ajax Bay (20 Dec 2020)

Better ^^^ than the image in the OP, noting "bike easily shifts into all combinations on the workstand".
The first item to replace is the small chainring. If you fit a new chain then, if you're getting chain suck occasionally now, you will swiftly become the world's expert with a worn ring / new chain combo. Refer to the image in my post #14.
The ziptie bodge is a mitigation not a solution.


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## rockyroller (21 Dec 2020)

Ajax Bay said:


> first item to replace is the small chainring


I intend to, but I'll have to drop it off at a shop for that


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## WesternBikingGirl (22 Dec 2020)

I'm not sure what this chain suck is. If someone want's to help me understand it I'd be grateful.


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## rockyroller (22 Dec 2020)

WesternBikingGirl said:


> I'm not sure what this chain suck is. If someone want's to help me understand it I'd be grateful.


when the chain is in the small chainring, and the chain doesn't release as it should, it clings to the small chain ring, getting sucked up in between the chainring & the chainstay. for me, it happens when the chain gets dirty, usually under load, like an out of the saddle climb


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## WesternBikingGirl (22 Dec 2020)

Got it, thanks. I assume lube helps?


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## rockyroller (22 Dec 2020)

WesternBikingGirl said:


> Got it, thanks. I assume lube helps?


not if it's thick gooey wet lube mixed w/ mud. a clean chain, properly lubed (w/ a "dry" product") helps


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## rockyroller (1 Jan 2021)

Ajax Bay said:


> Better ^^^ than the image in the OP, noting "bike easily shifts into all combinations on the workstand".
> The first item to replace is the small chainring. If you fit a new chain then, if you're getting chain suck occasionally now, you will swiftly become the world's expert with a worn ring / new chain combo. Refer to the image in my post #14.
> The ziptie bodge is a mitigation not a solution.


howdy, took the MTB out on a route that would normally produce the chain suck. featuring mud & a particular steep climb out of the saddle; no chain suck. I think the chain was monstrously filthy & my previous attempts to clean it were pathetically ineffective at best. finally did a proper job, off the bike, twice. maybe taking 2 links out helped too? regardless I ran the "trouble route" 3 times late yesterday w/ no chain suck. your thoughts?


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## Ajax Bay (1 Jan 2021)

No chain suck = happy days. Still using old chain but well cleaned and oiled, right?


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## Gunk (1 Jan 2021)

fossyant said:


> And get rid of the wheel reflectors



Every bike I buy, they’re the first to go in the bin!


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## rockyroller (1 Jan 2021)

Ajax Bay said:


> No chain suck = happy days. Still using old chain but well cleaned and oiled, right?


correct


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