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  1. #1
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    Replacement crankset options - what is compatible?

    Hey all, I am a newbie at crankset replacement, but have learned a lot in the last week. I have removed my old crankset and been looking at replacement options. The only thing I have not been able to figure out is what will definitely work as a replacement crankset. Am I right to assume that the new type of cranksets with external bearing BBs have all of the spacers I need to make them work on my bike?

    I have a 2002 Cannondale Jeckyll with a Shimano BB-ES70 73 x 113mm Octalink bottom bracket... Are all of the new outside bearing bottom brackets compatible? Is the chainline adjustable on this type of bottom brackets? Can I just buy any new Truvative Stylo crankset with the GXP BB and expect to be able to adjust it to fit and align?

    Thanks in advance for your superior crankset wisdom!

  2. #2
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    New outboard BB crankset works with 68 or 72 mm, and comes with spacers to adjust chainline if needed.

  3. #3
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    hmmmm.... so I bought a new Truvative crankset with the GXP BB and got it installed - torqued to the right specs, etc.... cool! Now I know how to replace cranksets! Unfortunately, the chainline for the new crankset does not line up with my front deraileur. My old BB is 68 mm, so I had to use a spacer on each side to install the GXP BB. I unscrewed the outer limit screw and adjusted the deraileur as far as possible and it still would not go into the big ring. So I took the BB apart and reinstalled with both spacers on the non-drive side. A little better, but still not enough... I cannot shift into the big ring. And there seems to be no way to move the crankset closer to the frame. Is there a way to move or adjust the front deraileur even further than the limit screws allow? Or do I need a new front deraileur or different crankset?

  4. #4
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    You definetly don't need a new FD. Doesn't matter what derailleur you have they are all the same.....no difference in chainline between them.

    Something doesn't sound right with your install.

  5. #5
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    Quote Originally Posted by mar_tad
    hmmmm.... so I bought a new Truvative crankset with the GXP BB and got it installed - torqued to the right specs, etc.... cool! Now I know how to replace cranksets! Unfortunately, the chainline for the new crankset does not line up with my front deraileur. My old BB is 68 mm, so I had to use a spacer on each side to install the GXP BB. I unscrewed the outer limit screw and adjusted the deraileur as far as possible and it still would not go into the big ring. So I took the BB apart and reinstalled with both spacers on the non-drive side. A little better, but still not enough... I cannot shift into the big ring. And there seems to be no way to move the crankset closer to the frame. Is there a way to move or adjust the front deraileur even further than the limit screws allow? Or do I need a new front deraileur or different crankset?
    What is the distance from the center of the seat tube (where the FD mounts) and the middle chainring? It should be close to 50mm.

  6. #6
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    Distance from center of tube to middle ring is about 50mm - the chainline stated in the install instructiuons for this crankset is 51mm, so moving both spacers to one side has created a 50mm chainline. Unfortunately it looks like I need a crankset with a 45mm chainline. Everything about the installation seems right and the crank works fine, it is the chainline that is a problem.

    So apparently Strafer is incorrect and cranksets with outboard BBs are not adjustable and I cannot buy just any Outboard BB crankset and make it work with my bike. Apparently different cranksets have different chainlines, so it seems I wasted my money on this crankset and need to find a crankset that has a narrower chainline.

    Can someone confirm this is correct? Do different BBs have different chainlines and they are not universal? Do I need to find a crankset that has a smaller chainline?

    If so, how do I compare cranksets based on their chainlines? This is not an apparent specification for cranksets. Is there some resource that compares cranksets that includes their chainline measurement? Or do I need to dig into the specifications for each crankset to find the chainline range?

  7. #7
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    Quote Originally Posted by mar_tad
    Distance from center of tube to middle ring is about 50mm - the chainline stated in the install instructiuons for this crankset is 51mm, so moving both spacers to one side has created a 50mm chainline. Unfortunately it looks like I need a crankset with a 45mm chainline. Everything about the installation seems right and the crank works fine, it is the chainline that is a problem.

    So apparently Strafer is incorrect and cranksets with outboard BBs are not adjustable and I cannot buy just any Outboard BB crankset and make it work with my bike. Apparently different cranksets have different chainlines, so it seems I wasted my money on this crankset and need to find a crankset that has a narrower chainline.

    Can someone confirm this is correct? Do different BBs have different chainlines and they are not universal? Do I need to find a crankset that has a smaller chainline?

    If so, how do I compare cranksets based on their chainlines? This is not an apparent specification for cranksets. Is there some resource that compares cranksets that includes their chainline measurement? Or do I need to dig into the specifications for each crankset to find the chainline range?
    No, Stafer IS correct. 50 (or 51) IS the standard chainline for an 8 or 9 speed cassette, so your crankset is fine. Standard chainline on the Shimano Octalink cranks from that time should be ~ 50mm as well, it is puzzling why yours was different. Maybe ask about this in c-dale forum.

    The problem sounds like your front deraileur setup. What kind is it? Can you take a picture of the crank/fd area?

  8. #8
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    Raceface crank on Jekyll ?

    This may help. There were other thread that showed up when I searched, so look around.

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    I could not find any relevant content on the Cannondale forum, so I created a separate post there. Jekyll 3000 Chainline issues - crankset options?

    I have a Shimano XT bottom pull front deraileur. The issue is that a crankset with a 51mm chainline will not fit my bike, and I need something closer to 45mm. Bottom line is it seems the new type of outboard BB crankset are not compatible with all newer MTBs. What cranksets are available with a 45mm chainline and how do I find one?

    For others out there considering replacing a crankset, be certain to measure your chainline and confirm that the new crankset has a matching chainline before purchasing. Chainline distance is measured from center line of the frame that holds the FD, to the middle chain ring. Apparently 51mm is common, but not universal.

  10. #10
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    I always thought cannondale's had a 48mm-50mm chainline...at least close to that. I would have thought spacers would have taken care of the difference if any.

    So are you selling your cranks?

  11. #11
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    Quote Originally Posted by mar_tad
    I could not find any relevant content on the Cannondale forum, so I created a separate post there. Jekyll 3000 Chainline issues - crankset options?

    I have a Shimano XT bottom pull front deraileur. The issue is that a crankset with a 51mm chainline will not fit my bike, and I need something closer to 45mm. Bottom line is it seems the new type of outboard BB crankset are not compatible with all newer MTBs. What cranksets are available with a 45mm chainline and how do I find one?

    For others out there considering replacing a crankset, be certain to measure your chainline and confirm that the new crankset has a matching chainline before purchasing. Chainline distance is measured from center line of the frame that holds the FD, to the middle chain ring. Apparently 51mm is common, but not universal.
    You bike does not need a 45mm chainline. Look at all the threads talking about the different cranks that people have put on the Jeckyl, including the race face external bb, which has a 49-51mm chainline. Not once does anyone mention needing a 45mm chainline. As I said before, the desired chainline is determined by the position and type of caseette/hub. Pretty much any 8-9 speed 135mm mtb hub is going to be in the same lateral possition on a bike (with the wheel centered). Further, since ~50 IS the standard, any front deraileur shoudl be able to acomodate it. You issue is not that you bike has a shorter chainline (it's got nothing to do with your bike) it that you DERAILLEUR can't accomodate it.

    However, if you do look at that thread I linked to, there is a clue as to what the problem may be. It looks like there were issues with the left crank arm of some cranksets clearing the rear triangle, and some people needed to cheat the whole crank assemble to the non-driveside to clear. It could be possible that the crankset that was on your bike had such a problem, so the crank was cheated over, thus shortening the chainline, and the front deraileur was modified to accommodate that. In any event SOMETHING is screwy with your front der if it cannot accommodate a 50mm chainline. If your cranks can spin without hitting the rear triangle, you should not need to cheat it over.



    However,

  12. #12
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    Rather than trying yet another set of cranks, try a new front derailleur.
    You can find LX for around $20, a lot cheaper than trying another crankset.

  13. #13
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    You need to adjust the FD to work with your new cranks.
    If I disagree with you, it's because you are wrong.

  14. #14
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    Quote Originally Posted by mar_tad
    I could not find any relevant content on the Cannondale forum, so I created a separate post there. Jekyll 3000 Chainline issues - crankset options?

    I have a Shimano XT bottom pull front deraileur. The issue is that a crankset with a 51mm chainline will not fit my bike, and I need something closer to 45mm. Bottom line is it seems the new type of outboard BB crankset are not compatible with all newer MTBs. What cranksets are available with a 45mm chainline and how do I find one?

    For others out there considering replacing a crankset, be certain to measure your chainline and confirm that the new crankset has a matching chainline before purchasing. Chainline distance is measured from center line of the frame that holds the FD, to the middle chain ring. Apparently 51mm is common, but not universal.
    Here, search some more.....

    External BB/Cranks on a Jekyll

    LOTS of external bb cranks on Jeckyls. Race Face, Shimano SLX and XTR, Truvativ. They are all standard chainlines.

  15. #15
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    Not all front derailleurs are created equal in terms of chainline. Road derailleurs are optimized for a 43.5 mm or 45mm chainline, older mountain derailleurs at 47.5, most current ones at 50. You sure you're using that high limit screw correctly?
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  16. #16
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    You know I have had a FD that had worn so bad where the HL screw mates that adjustment was impossible. I sure wouldn't think it is the problem seeing that it worked before the swap.....but hell...I'm just talking out loud.

  17. #17
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    How about a picture or 5 to help us help you?

  18. #18
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    Thank you Larlev, good point. I bought the bike new and I am replacing the crankset for the first time after 4000+ flawless miles. The Shimano Octalink with CODA crankarms worked perfectly with the FD - never a problem. Now with the new crankset, the FD barely shifts into the middle ring and is about 5mm from shifting into the big ring. All BB threaded parts are properly torqued and the installation is otherwise perfect. There is no extra play in the FD - it is not a limiter screw issue. The issue is the FD does not have enough reach. Keep in mind this is a Jekyll 3000, which is somewhat unique and may be slightly different in design compared to other Jekylls and other year models, but I am not certain on this. The vertical part of the rear triangle where the FD attaches is slightly offset from the seat tube by design, so you cannot compare to a hardtail for example.

  19. #19
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    photos of the offending part

    here are some photos....
    Attached Images Attached Images

  20. #20
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    And those photos are to illustrate just what?
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  21. #21
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    Quote Originally Posted by Bikinfoolferlife
    And those photos are to illustrate just what?
    We asked him for pictures.

  22. #22
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    Quote Originally Posted by mar_tad
    Thank you Larlev, good point. I bought the bike new and I am replacing the crankset for the first time after 4000+ flawless miles. The Shimano Octalink with CODA crankarms worked perfectly with the FD - never a problem. Now with the new crankset, the FD barely shifts into the middle ring and is about 5mm from shifting into the big ring. All BB threaded parts are properly torqued and the installation is otherwise perfect. There is no extra play in the FD - it is not a limiter screw issue. The issue is the FD does not have enough reach. Keep in mind this is a Jekyll 3000, which is somewhat unique and may be slightly different in design compared to other Jekylls and other year models, but I am not certain on this. The vertical part of the rear triangle where the FD attaches is slightly offset from the seat tube by design, so you cannot compare to a hardtail for example.
    So, the tube that the front der clamps to sits to the non-drive side of center? If that is the case, I guess that explains why the der does not reach. Find out on the C-dale forum if they are all like this (I would guess they are), and if so, what deraileurs worked with standard chainlines.

    I'm sure you've done this already, but just to be sure, in addition to letting out the limit screw, you did tighten (shorten) the front der cables, right?

    I think your solution to this is going to be in figuring out how to get a 50mm chainline to work. The only way to get a shorter chainline is to get a non-external bb and play with the axle length and possitioning. The problem you will likely run into if you just get a shorter spindle is that (according to many of the posts on the c-dale forum discussing this) that the rear triangle clearance is tight on the non-driveside. So you may need to get a 73mm bb and then put spacers on the non-drive side to cheat the crankset over. Honestly, this is not a great solution, because your pedals will be off center. They may have been this entire time.

  23. #23
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    Quote Originally Posted by kapusta
    So, the tube that the front der clamps to sits to the non-drive side of center? If that is the case, I guess that explains why the der does not reach. Find out on the C-dale forum if they are all like this (I would guess they are), and if so, what deraileurs worked with standard chainlines.

    I'm sure you've done this already, but just to be sure, in addition to letting out the limit screw, you did tighten (shorten) the front der cables, right?
    Correct, the tube where the FD attaches sits just off-center to the non-drive side on this bike. I tried to tighten the FD cable, but there is no play... the FD is extended to it's maximum and it is not far enough.

    Are there bottom pull FDs that extend 5mm farther than a normal XT? I would think FD reach is a pretty standard distance. Seems like my only choice is to find a different crankset with a thinner chainline.

  24. #24
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    Quote Originally Posted by mar_tad
    Correct, the tube where the FD attaches sits just off-center to the non-drive side on this bike. I tried to tighten the FD cable, but there is no play... the FD is extended to it's maximum and it is not far enough.

    Are there bottom pull FDs that extend 5mm farther than a normal XT? I would think FD reach is a pretty standard distance. Seems like my only choice is to find a different crankset with a thinner chainline.
    I've not heard of alternate fd's, nor if they can be modified a bit. Have you run this by the folk on the Cannondale board here?
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  25. #25
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    I have never heard of a FD that travels further than another, they are all made the same. Have you called cannondale and asked what the chainline is? I would have bet a finger that it would have been 48mm-50mm which is standard. Can you use more spacers in the BB install?

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