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  1. #1
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    Cant shift into large chainring-help (just replaced crankset)

    I just bent a chainring and had to replace my entire crankset. The crankset install went OK I thought. Now, I am trying to get just front derailleur adjusted. However, once I adjust the front derailleur to where it shifts smoothly into 1 and 2 - I cant get it to shift into 3. To be clear, I CANT even get it to click into 3. It seems like I have the derailleur so tight that it physically cant move enough (via the chain tension) to allow the 3 to be entered.

    What seems weird is that based on the location of the largest chainring, it doesnt appear that the derailleur can move far enough to force the chain onto the largest chainring.

    This is my first time working on this part of my bike so I may just be doing something completely wrong - but I watched a few tutorials on this subject and none really addressed the issue I am running into.

    Please let me know if you have any suggestions... I can post photos if there is anything specific I can show you that might help with the troubleshooting...thanks.

  2. #2
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    Possible caues:

    1) "H" limit screw needs to be adjusted.
    2) New crankset is offset to the right. Check instructions for spacers, etc.
    3) Derailleur cage is hitting large chainring.
    4) Chainring is larger in diameter (more teeth) than your old one making the chain too short to get onto the large chainring.

    Try removing the chain and check/adjust derailleur travel.

  3. #3
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    Quote Originally Posted by billee
    Possible caues:

    1) "H" limit screw needs to be adjusted.
    2) New crankset is offset to the right. Check instructions for spacers, etc.
    3) Derailleur cage is hitting large chainring.
    4) Chainring is larger in diameter (more teeth) than your old one making the chain too short to get onto the large chainring.

    Try removing the chain and check/adjust derailleur travel.
    1. I have adjusted the H limit screw to allow the derailleur to move more but didnt fix the issue.
    2. What do you mean "offset to the right".... ? Do you mean the crankset needs to move closer to the center of the bike?? This seems reasonable but I think it is moved in as far as it can go.

    3. I had to adjust derailleur to fix this... was happening at first.

    4. the Large chainring on old crank and new crank are both 42.

    Been screwing with it for a couple hours now and have tried most things that seemed like possible solutions... it seems like if the crank could move further in towards the center of the Bottom Bracket then that might fix the issue... is there anyway I can tell if there is more room to move the crank in further? i really dont think there is more room but always a possibility that I did this wrong... THanks for help.

  4. #4
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    Here, I have the front derailleur in the furthest position that it will move outward. As you can see, the chain doesnt even have enough room to turn on the big ring without scraping the derailleur. I beleive it is at the correct height and it is parallel to the ring... it just wont move out far enough to allow the chain to stay on the 3 ring. Again - total noob with working on derailleurs so any advice would be appreciated... I wouldnt think that the new crankset isnt compatiable but am open to any possiblility at this point.






  5. #5
    FresnoGiant
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    Do you have any spacer rings on the drive-side of the crankset? These are metal rings that fit between the crank and the bottom bracket. If so, you can remove one or more to see if the crank is moved into the frame enough to clear the derailleur. Another possibility is the cage on the FD may be bent. Any way that could have happened while working on the crank install? One last question, sort of off-topic. Why didn't you just replace the bent chainring instead of a whole new crankset?

  6. #6
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    Quote Originally Posted by jersey0826
    Do you have any spacer rings on the drive-side of the crankset? These are metal rings that fit between the crank and the bottom bracket. If so, you can remove one or more to see if the crank is moved into the frame enough to clear the derailleur. Another possibility is the cage on the FD may be bent. Any way that could have happened while working on the crank install? One last question, sort of off-topic. Why didn't you just replace the bent chainring instead of a whole new crankset?
    The old crankset had riveted (all the chainrings are permanently connected to each other) chainrings so I couldnt replace them individually... I did buy a new crankset that would allow me to change them individually if I bend one again in the future though. You usually find this type of crankset on lower / entry level bikes.

    I dont believe the cage is bent.

    I am not sure if there are any spacers or not... however, when I looked closer - it almost appears that the bottom bracket bearing is not seated properly... look at the image below with the red arrow... does that look wrong? I guess I can take the crankset back off if I need to look for any spacers... I dont recall there being any though but didnt really look.

    The BB could have been pulled out some when I bent the chainring and pedaled a few times which caused my bent ring to grind against my bike frame... I guess that tension could have caused the BB to pull out some which may be why it doesnt line up now.




  7. #7
    PCC
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    What cranks did you put onto your bike? I cannot tell from the pictures.

    1) If it is an older-style crank set (square taper or Octalink/ISIS) then you need to ensure that you have tightened the crank bolts enough to seat the cranks where they need to be. Measure from the middle of the downtube to the middle of the middle chainring. 50mm, or just a hair under 2" is what it should be.

    2) Did you disconnect the cable from the front derailleur at any time? If you did you might have indexed the shifter incorrectly. Click the release button on the shifter a few times like you are shifting to the smallest chainring. Pull on the cable to see if it pulls out any excess cable. If so try loosening the anchor bolt, take out the slack in the cable and tighten it again and see if this works.

  8. #8
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    Quote Originally Posted by PCC
    What cranks did you put onto your bike? I cannot tell from the pictures.

    1) If it is an older-style crank set (square taper or Octalink/ISIS) then you need to ensure that you have tightened the crank bolts enough to seat the cranks where they need to be. Measure from the middle of the downtube to the middle of the middle chainring. 50mm, or just a hair under 2" is what it should be.

    2) Did you disconnect the cable from the front derailleur at any time? If you did you might have indexed the shifter incorrectly. Click the release button on the shifter a few times like you are shifting to the smallest chainring. Pull on the cable to see if it pulls out any excess cable. If so try loosening the anchor bolt, take out the slack in the cable and tighten it again and see if this works.
    I bought a square taper crankset (Shimano Alivio) - I currently have the crankset off right now so I will make sure to measure the distance as you mentioned when I put it back on.


    I did disconnect the cable from the the FD. I have tried a bunch of different approaches to make sure the the tension is correct on the FD...however, I just cant seem to physically get the FD cage moved far enough for the chain to stay on the big chainring... at this point seems like the problem has to be that the crankset wasnt installed close enough to the downtube or their is a space in the way, etc. Working on checking that right now...

    Or to put it a different way - I have the FD cable disconnected and have been trying to manually put the FD cage in the proper position that would allow the chain to seat on the big ring properly and cant get the FD to move far enough over for the chain to stay on the big ring properly...

    Could you tell me if the way the BB is seated looks correct (red arrow) ?? I have never removd a BB so I am not sure if it is supposed to stick out a little bit or not...

  9. #9
    FresnoGiant
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    The BB looks fine, but there is a considerable gap between the frame and the chainrings. This is where there would normally be a spacer(or several). +1 on what PCC said. Measure the chainline to see if it exceeds the norm. If it does, you may not be tigheting the crank arm fully. If it is where it should be, then you may need a new FD. It is possible that it is not compatible with the new crankset.

  10. #10
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    I recently did the same thing with my daughter's Giant, which also came with a crank with riveted chain rings (MC-19). I found the first set of cranks (I think an Alivio) I tried placed the rings too close to the frame (the opposite problem to yours) and that an MC-440 maintained the original chain line. Shimano obviously has some different chainlines on its square taper bottom brackets, but I haven't seen anything that details what these are.

    Put the original cranks back on, tighten them up to spec and measure how far the smallest ring is from the frame. Try the same thing with the new cranks and this will show if the old BB and crankset produces a different chainline.

    I might have missed it in your post, but the simplest reason might be that you are not pulling enough cable. Try pushing the derailleur into the right position after completely remove the "h" limit screw to make sure this isn't affecting it.

    On my bike I also found that the e-type derailleur could not cope with the additional diameter of the 44 tooth chain ring compared to the original 42 tooth ring as there was no vertical adjustment.

    Tim

  11. #11
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    After skimming this thread, it seems to me that the new crankset has moved the chainline outwards past the point where the existing front derailleur can operate.

    Verify that the installation of the new crankset is correct. If it is correct, you'll most likely need a different front derailleur to accommodate the new chainline.

  12. #12
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    Looks like the BB spindle is too long!

  13. #13
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    Unfortunately - I already trashed the old crankset so I cant do any comparisons. Being the rookie mtb mechanic that I am - I really didnt even think this type of issue would arise... oh wel - live and learn.

    As far the installation of the new crankset - I really dont see how it couldn't be installed properly. It is tightened down and sits completely flush with the bottom bracket so there is not any room for it to move any closer to the center of the BB.

    The large ring size didnt change - old and new are both 42.

    LIke a few of you have said - I guess the new crankset is not compatible with the FD. I just find it kinda stupid that are not compatible - but maybe, just maybe - they have a method to this madness! Thanks for all the help guys... will see what I can find out today by calling the LBS that sold me the crankset.

    Is there any risk to running my bike as a 2 X 8 right now until I change out the FD??

    ALSO - I think front derailleur on my bike (Shimano C050) is typically matched with a BB that has a 47.5mm chainline. My guess is that my BB and crank is setup larger that 47.5mm (maybe more like 50mm) ... does that make sense??
    Last edited by Mikey_Dawg; 07-06-2009 at 05:29 AM.

  14. #14
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    Quote Originally Posted by Mikey_Dawg
    Is there any risk to running my bike as a 2 X 8 right now until I change out the FD??
    Using your current derailleur and confining your use to the small and middle rings should be okay.

  15. #15
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    You need a new BB

    The BB spindle length is wrong for the crank you have. Every square taper crankset uses a different length BB spindle. I believe tha Alivio uses a 113 mm spindle length. You said you have the original BB in there still and that is the problem as it has changed your chainline and is out of your front derailleur spec range. The cranks you have must be matched to the proper BB spindle length.
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  16. #16
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    Quote Originally Posted by danoalb
    The BB spindle length is wrong for the crank you have. Every square taper crankset uses a different length BB spindle. I believe tha Alivio uses a 113 mm spindle length. You said you have the original BB in there still and that is the problem as it has changed your chainline and is out of your front derailleur spec range. The cranks you have must be matched to the proper BB spindle length.
    That's my guess as well - BB spindle is too long.
    When I see an adult on a bicycle, I do not despair for the future of the human race. ~H.G. Wells

  17. #17
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    Quote Originally Posted by cutthroat
    That's my guess as well - BB spindle is too long.
    Thanks... little annoyed with LBS since they said this crank would work just fine but I should had been more educated myself before just buying what they suggested.

    I guess my only option is to get a new BB that will work with my new crank now since my crankset is used...

    I beleive the old crankset was compatible with a 122.5mm spindle from what I have read.

    So I need to find a square taper BB with a 113mm spindle? Correct?

    How do I konw if I need a 65 x 113mm or 73mm x 113mm? Is the 65/73 just the diameter of the botttom bracket?

  18. #18
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    68/73mm is the width of the BB shell
    I'm a member of NSMBA and IMBA Canada

  19. #19
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    Here's what I think you need

    MOST mtn bikes especially older ones use a 68mm shell with so I would use this bb.

    http://www.bikeman.com/CR5368.html


    Or if you want to be sure you can take your old bb out and it should say the shell size right on it.
    Early to bed early to RIZE makes a man healthy, wealthy <(scratch that) and wize.

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  20. #20
    PCC
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    Can you get a better picture of the cable anchor? It's the part at the bottom of this picture:

  21. #21
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    Quote Originally Posted by PCC
    Can you get a better picture of the cable anchor? It's the part at the bottom of this picture:
    Later tonight if you think it would be useful...

    You thinking I reconnected the cable wrong? I wouldnt put it past myself... seems like a couple different ways that you could secure... none of which seemed to be the obvious choice IMO...

  22. #22
    PCC
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    From the angle of that picture it looks like it was incorrectly mounted but I need a better shot/angle to be sure.

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