Disc brake, Chainline Question.
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  1. #1
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    Disc brake, Chainline Question.

    All. I am worried about the chainline on my son's bike. I have a solution for it, but I am not sure if this is the best solution. The bigger issue is this. I am worried about the fact that the chain is hitting his crank arm on his road bike. Here is the setup.

    Specialized Allez Sprint Disc (142 through axle rear spacing)
    FSA crankset, micro rings to help with Jr gearing.
    11 speed drivetrain.
    Garmin Vector 2 pedals.

    When he is sprinting, due to Jr. gearing, he is in his 11 creating a pretty tight chainline. As a result his chain is hitting the pod part on his vector 2 pedals. This keeps breaking and popping off the pod deal that fits in the back of the peddle. The concern is the fact that these pods keep breaking. The bigger worry is, the fact that the chain is THAT close to the crank. I am not sure the component groups are addressing chainline with the through axles and 11 speed drivetrains, but I am tempted to put some spacers on the spindles of his crank. Not sure if the spindle has enough room however to do so. Anyone have any thoughts one this? Thanks.

    BTW. I did call Garmin about this, and they did reference the issue, so this is not new, but they created the vector 3 as a result. This does not address the concerns of chainline.

  2. #2
    'brifter' is a lame word.
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    I don't think you understand chainline. On modern bicycles there really isn't anything you can do to adjust it. It is what it is. Chainline is also not what is causing problems w/ the pods hitting the chain. That said without seeing the bike in person it's doing to be hard to give you good advice.
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  3. #3
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    ^^^
    Yeah, this sounds odd. What is the chainring combo up front? Maybe a handful of detailed photos of the setup would help. Only thing I can dream up is that there isn't enough tension on the chain. When he's out of the saddle sprinting, the chain is flopping all over the place (below the chainstay) and hitting the pod.

  4. #4
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    I will see if I can get some photos. That said, with all of the newest bb combinations I know some require spacers to get a ďsuggestedĒ chainline. That said I would think you still have to have some level of normal or the front shifting becomes a challenge. Iím not entirely sure if this crankset chainring setup was initially 10 speed, and wonder if this impacts the chainline. Cxwrench. Maybe I donít understand chainline, but I have had to dig into understanding it for boost spacing and such on the mtb. I do know this. Having a chain that close to a crank in the 50-11 sure seams too close.

  5. #5
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    I want to be sure I understand what gearing you have there. It would seam to me that a 50x11 would be way to big for junior gear restrictions. A bunch of good photos of the drivetrain are essential to even comment further on this.

  6. #6
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    You are correct on the gearing sizing. I block out the lowers for racing, but the 50 gives us more room on the cassette to not have to bock out half the cassette.

    I am going to try and get pics up tonight.

  7. #7
    'brifter' is a lame word.
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    Quote Originally Posted by Rmabus View Post
    You are correct on the gearing sizing. I block out the lowers for racing, but the 50 gives us more room on the cassette to not have to bock out half the cassette.

    I am going to try and get pics up tonight.
    Wait...in your first post your said: "FSA crankset, micro rings to help with Jr gearing." As well as: "When he is sprinting, due to Jr. gearing, he is in his 11 creating a pretty tight chainline."

    You follow up with: "I block out the lowers for racing, but the 50 gives us more room on the cassette to not have to bock out half the cassette."

    You wouldn't have to block out 'half the cassette, just the 11, 12, and 13. If your kid is going to nationals you're not allowed to limit derailleur travel to achieve junior gear limitations. You must use a junior cassette that Shimano make,(if you're using a 50 or 52) it's a 14-28. If you're blocking out gears why is there an issue w/ the chain? Are you really using the smaller chainrings and then using the whole cassette?
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  8. #8
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    Good point. I only block them when he is racing. For the group rides with adults around here I drop it back to the 11. I have my opinions about jr gearing but thats a different forum topic. I was not clear on that. Sorry.

  9. #9
    'brifter' is a lame word.
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    Quote Originally Posted by Rmabus View Post
    Good point. I only block them when he is racing. For the group rides with adults around here I drop it back to the 11. I have my opinions about jr gearing but thats a different forum topic. I was not clear on that. Sorry.
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  10. #10
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    For sure. May be doing him a dis service to let him stay in regular gearing for group rides but he is races about 85% Mtb to 15% road right now, and mostly trains on the road for convenience with us living in Dallas.

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    Quote Originally Posted by Rmabus View Post
    For sure. May be doing him a dis service to let him stay in regular gearing for group rides but he is races about 85% Mtb to 15% road right now, and mostly trains on the road for convenience with us living in Dallas.
    So, the junior gearing thing has absolutely nothing at all to do with the issue he's having then? This is a standard compact crank on an 11 speed with an 11 tooth small cog right?
    Bottom line in this thread at this point is, pictures it's not worth talking about.

  12. #12
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    202. I know I know. We were racing cross last night and I now a few new mechanical issues need to be sorted on the xc bikes before we get to this weekend. I will get pics as soon as I can. Maybe tonight but I have a chain to replace, a buddies wheel that now needs Stans, and a sram shifter from said buddies bike that is not working properly. Oh, and a boa that somehow got cut on a rotor during an unfortunately "miss hap" with another rider.

  13. #13
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    Quote Originally Posted by Rmabus View Post
    202. I know I know. We were racing cross last night and I now a few new mechanical issues need to be sorted on the xc bikes before we get to this weekend. I will get pics as soon as I can. Maybe tonight but I have a chain to replace, a buddies wheel that now needs Stans, and a sram shifter from said buddies bike that is not working properly. Oh, and a boa that somehow got cut on a rotor during an unfortunately "miss hap" with another rider.
    See you then

  14. #14
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    Can you just use the data from the non drive side - set it up as a single sided power (vector 2s)_meter and pull the pod off the drive side? Unless he has a big left / right imbalance, the numbers are going to be close enough I would think for sure during a race.
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  15. #15
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    Srode. So funny you offer that. The theoretical answer is yes. The actual answer though is that the brain for the Garmin for communication is in the drive side pedal. So not really.

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    Quote Originally Posted by Rmabus View Post
    Srode. So funny you offer that. The theoretical answer is yes. The actual answer though is that the brain for the Garmin for communication is in the drive side pedal. So not really.
    are you sure, this article says the left or NDS

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  17. #17
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    Quote Originally Posted by Rmabus View Post
    Iím not entirely sure if this crankset chainring setup was initially 10 speed, and wonder if this impacts the chainline. Cxwrench. Maybe I donít understand chainline
    The chain line is the same for 9, 10, and 11 sp cassettes because the frame spacing and cassette width is the same. Just gears more closely spaced. I'm having a real hard time figuring out how the chain can get to the right of the crank arm in order to hit the pedal. If it was doing this it would also be doing significant damage to the pedal end of the crank arm. Most confusing.

  18. #18
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    So I did some looking into this. Fortunately I have the same frame in a Dura Ace setup. Goofy thing. The chainline appears to meet the minimum standard but in looking at it I think the chainring may be the issue. The spacing is way farther out. Maybe 1/4 inch.

    I have really come to a new realization. I think the issues with this setup have everything to do with the crankset and chainrings. The rings I was using were not FSA. I think as a result they impacted spacing all the way around. I went to a different chainring this weekend, and it really made a big difference in terms of getting the chainring a little farther away from the crank arm. That said, when dialing in the front DR, I noticed it now shifts like crap and was difficult to setup. I will be getting him some new chainrings soon designed for an FSA crankset. We can see if that finally makes a difference.
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    Last edited by Rmabus; 4 Weeks Ago at 08:07 AM.

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