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Unwanted Chain Pickup - Very Grumpy Rider.

wolfsbane2kwolfsbane2k Posts: 2,950
edited July 2019 in Workshop
Ok, I'm fed up. Broken main bike means I'm back on the old one, which, despite having a new frame fitted and a full inspection/service post re-build from the shop and then stored for 8 months while I rode N+1 , I've still got issues.

Currently running a Triban 540 with shimano kit
Front Derailleur - Shimano 105 10 speed (FD-5700)
Rear Derailleru - Shimano 105 10 speed ( RD- 5700 )
Chainset - Shimano FC-5750 50-34 chainset.
Cassette Shimano 105 CS-5700 11-28
Bottom Bracket - BBR60 English
Chain - KMC X10-EL - brand new.

As far as I can tell, according the 2019-2020 Shimano Products compatibility information list, other than the chain being a KMC chain, this Is all meant to work, and I can't imagine the KMC chain being the cause - the bike comes with a KMC chain by default.

I've stuck a gopro on the seatstay looking at the drivetrain to understand what's happening during a ride.

What's happening is the chain is being picked up from the small chainring every now and again when in the 2 lower toothed gears, and either dropped back onto the smaller chain ring, or straight off the chainring entirely and into the frame.

It's also throwing the chain when shifting in the big ring from the T28 down two gears on the cassette at a time.

The derailleurs are set to the right limits, it's all dialled in. I've tried it with a CS-4600 12-28 cassette I had lurking around, and that suffers the same issues.

It feels like the chainset is about 1-2mm closer to the frame than it should be, but the crankset didn't come with spacers,

Given that this is happening randomly, I've found myself very in very precarious positions with the chain dropped and I'm quite scared by it happening and not being able to apply power/escape just when I need it.

My remaining thought is possibly a stiff rear derailleur not picking up any chain slack properly, but that seems overkill.

Ideas/clues/pointers really appreciated.
Intent on Cycling Commuting on a budget, but keep on breaking/crashing/finding nice stuff to buy.
Bike 1 (Broken) - Bike 2(Borked) - Bike 3(broken spokes) - Bike 4( Needs Work) - Bike 5 (in bits) - Bike 6* ...

Posts

  • jgsijgsi Posts: 5,025
    There is something very odd that your 5700 is playing up.
    I have it on my hack Ribble and it is 100% bombproof.
    I am going to suggest that the frame might out of true at the back or at least the hanger?
    You wouldnt or shouldnt even think about spacers on a standard HT bottom bracket and 5700 crankset... there is no requirement.
    Some hi res pictures of the bike from the rear , top and side might give us clues.
  • keef66keef66 Posts: 13,286
    Is the chain the right length? I know it's new but any stiff links? Is it joined by a KMC link and is that correctly snapped shut?

    Not an answer to the question but can you fit a Deda dog fang or a K-edge chain keeper to physically stop it dropping off the inside of the small ring?
  • wolfsbane2kwolfsbane2k Posts: 2,950
    edited July 2019
    keef66 wrote:
    Is the chain the right length? I know it's new but any stiff links? Is it joined by a KMC link and is that correctly snapped shut?

    Not an answer to the question but can you fit a Deda dog fang or a K-edge chain keeper to physically stop it dropping off the inside of the small ring?

    Yep, KMC 10spd quick link, snapped shut properly, no obvious stiff links.

    I ordered a deda dog fang yesterday...
    Intent on Cycling Commuting on a budget, but keep on breaking/crashing/finding nice stuff to buy.
    Bike 1 (Broken) - Bike 2(Borked) - Bike 3(broken spokes) - Bike 4( Needs Work) - Bike 5 (in bits) - Bike 6* ...
  • wolfsbane2kwolfsbane2k Posts: 2,950
    jgsi wrote:
    There is something very odd that your 5700 is playing up.
    I have it on my hack Ribble and it is 100% bombproof.
    I am going to suggest that the frame might out of true at the back or at least the hanger?
    You wouldnt or shouldnt even think about spacers on a standard HT bottom bracket and 5700 crankset... there is no requirement.
    Some hi res pictures of the bike from the rear , top and side might give us clues.

    That's my thoughts, and I just can't put my fingers on the problem. Will grab some hi-res pictures when I can.
    With a brand new frame fitted, I took it home and put it in long term storage on a hanger in the garage roof space (without riding it) which is pretty empty, where no one else goes or could knock it over, and then checked the hanger with a park tools alignment tool when I got it down ready to ride as a "just in case"; was bang on alignment. I'm really annoyed.

    Before the frame swap I was having similar issues, which is one of the reasons I N+1'd, but it definitely seems more pronounced now ( or after riding for 8 months on a 4700 equipped bike without any issues at all, i'm now significantly more aware of them)
    Intent on Cycling Commuting on a budget, but keep on breaking/crashing/finding nice stuff to buy.
    Bike 1 (Broken) - Bike 2(Borked) - Bike 3(broken spokes) - Bike 4( Needs Work) - Bike 5 (in bits) - Bike 6* ...
  • AlejandrosdogAlejandrosdog Posts: 2,007
    I would check the rear derailleur is pivoting feely and tha in its long rest hasn't suffered from some corrosion. (spray liberally with GT85 and manually cycle a few times)

    Also check that the chain is tensioning the derailleur a little on the small front small rear combo. (your description wasn't absolutely clear to me)

    It doesn't sound like a hanger issue but whilst youre fannying around id check that too if you have a hanger gauge.

    BUT it does sound like your chainwheel may be worn or have a high spot somewhere so check it against a known new ring and see. sometimes it doesn't look like the classic shark tooth sign of wear. The symptom of damage or chainring wear is the chain gets thrown infrequently and if youre unlucky ends in a frame gnarling chain-suck event. Plus check FD and the limit screws again just in case. Things get knocked in storage.

    re the inconsistent rear changing. check the cable where it's inside the shifter. You're looking for signs its fraying.
    Also pull manually, does it feel smooth or gritty, it should feel smooth. If its fraying replace the cable. if its not smooth replace the outers as well. I'm assuming the shop lifted finishing kit straight off the old frame and plonked it on the new one.

    You are right though, it should all work perfectly.

    if that doesn't work, put some soothing music on, turn off your phone get a cup of tea and rebuild the transmission parts. it should take less than an hour even if you've never done it before. 20 mins if you have. (maybe a smidge more if you replace your bartape)
  • faster97faster97 Posts: 33
    The first issue is not unusual in my experience and the answer is simply to not use that combination of gears - just use the equivalent combination in the big ring instead.

    I suspect the second issue is caused by setting the front derailleur up in such a way to make the small-small combination tolerable ie the front derailleur is adjusted far enough to the right so that it doesn't rub the chain in small-small, but this then increases the chance of throwing the chain off to the outside in the big ring.

    There is no good reason to ever use small-small.
  • Unless a mechanic discovers a point where the drivetrain works perfectly when cross chaining (small-small or big-big) then there is an increased risk of problems occurring. It has been said before that to guarantee trouble free functioning, the aforementioned extreme combinations should be avoided. 10 cogs may just give you 14 possibly 15 gear combinations that won't give you trouble. I am always mystified why anyone wants to be in the bottom gear on the big ring. Why do that? I doubt that the designers meant for that to be used.

    Insum, you are experiencing problems because you are cross chaining.
  • cyclecliniccycleclinic Posts: 6,863
    What about ring wear. I have had chainring pickup issues before due to ring wear. The thing is we are guessing..

    The a number of things that could cause this. Many of which have been mentioned already.
    http://www.thecycleclinic.co.uk -wheel building and other stuff.
  • If this was my bike I would check the following

    1. Putting a bike in storage, even in a garage, can corrode the small parts of the chain and they can stick. You may not notice it initially but its not until you literally bend every link that you can come across not enough play between some links. So go over the entire chain and wiggle every link by hand and spray WD40 on every link as you do this. If everything is fine then wipe off and apply chain lube.

    2. Front Mech might be out. Check out the width tolerances on the chain rubbing against the inside of the cage and make sure they are all ok. It might simply be that in its not been setup against the proper gear ratios for clearance seeing as you keep having issues when in the upper and lower end of the cassette.

    3. Check tightness of cranks and crank arm. Make sure they are tight against the bottom bracket and theres no play left and right across the BB.

    4. Check the chain space from the cassette using the B-screw on the rear mech. A chain i had once kept jumping gears and I found out it was too close the the cogs on the cassette.

    From what you are suggesting though it sounds to me like the High and Low screws need adjusting on the rear mech. I know you said that it all aligns but the fact is it can look like its aligned but still pop the chain out either end if theres too much leeway in the H & L setup. I would definitely re-check the upper and lower limits on the rear mech.
    Forget all the nonsense about not being in the big ring and big cog or little ring and little cog...yes it does put the most tension on the chain but the fact remains a proper setup gearing system is designed to be used this way if needs be, otherwise the manufacturers wouldnt have designed it this way in the first place. Ive run a 52 front to a 32 rear for decades and never had a problem even when i weighed 23 stone putting some proper effort through the cranks. Its an old wives tale.
  • photonic69photonic69 Posts: 994
    Hmm... Go back to basics and start all over again. Download the Shimano Dealer Guide and set it all up again from scratch:

    https://si.shimano.com/pdfs/dm/DM-GN0001-23-ENG.pdf

    Sounds like it could be the FD not perfectly aligned with the Chainrings? Easy to check by dropping chain, winding FD out so outer edge is in line with the big chain ring and using a long hex wrench against the outside of the big chainring rotate it back and forth ensuring the FD is completely parallel to it. Also check height of FD against outer chainring for a 2-3mmm gap.

    HTH

    Nick
  • faster97faster97 Posts: 33
    Forget all the nonsense about not being in the big ring and big cog or little ring and little cog...yes it does put the most tension on the chain but the fact remains a proper setup gearing system is designed to be used this way if needs be, otherwise the manufacturers wouldnt have designed it this way in the first place.

    This isn't always the case. Even when perfectly set up, you're quite likely to run into problems like the OP describes when trying to use small-small, especially with a compact crankset and short chainstays.

    Shimano know this. When set up with a compact crankset, many Di2 systems won't actually let you select the two gears the OP is having issues with for this very reason.

    The OP has correctly identified the problem in his first post - the crankset is a little too far over to the left to do what he wants to do. All the talk about derailleurs and adjustments above is pointless. The problem is (which I think the OP understands) is that if you draw a straight line between the small front ring and the 11t, the big ring is in the way.

    You could shim the crankset over a bit (presumably you'd have to machine a bit off the other side of the BB shell to do this) and make the bike work perfectly in small-small, but then you'd have a rubbish chainline in big-big.

    Both my bikes do exactly the same thing and sound like a bag of spanners in small-small. Everything rubs on everything else! This doesn't bother me at all, as all of the gears I actually use (including big-big) work perfectly.

    There is nothing wrong with the bike imo.
  • paulbnixpaulbnix Posts: 466
    I had a similar issue when I replaced the outer ring on an FSA chainset.
    The chain was catching on the inner side of the outer ring when I was in small front and the smaller rear cogs.
    I fitted a shim on the nds side and it fixed the problem. I think it was 1mm.
    I had a MegaExo bb and chainset so a different method of preloading the bearings but I don’t remember any issues.
    It was a while ago so I can’t remember where I got the shim from but I would suggest it’s worth a try.
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