Mary EBB, How to adjust chain tension- Mtbr.com
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  1. #1
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    Mary EBB, How to adjust chain tension

    Alright, had my Mary a couple of weeks and have started to stretch the chain. Anyone know where to find documentation on how to adjust the BB or could you explain in a nutshell?

  2. #2
    ridin' Mary
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    I recently got a Mary, and changed out the chainring, so it needed some retentioning. I loosened the two grub screws that secure the EBB, but it wouldn't rotate easily. I have the full circle Bottom Bracket tool, but this required that I remove the crank arm on one side to get the BB tool onto the bearings so I could use that to move the EBB. Not optimal.

    Since then I dug through my toolbox and found an old Sugino BB too that is the half-circle with a pin variety. When I readjusted my EBB into an uppermost position to avoid pedal strikes, then I used this tool and it worked great without having to remove the crank arms.

    You just need something that can give you some leverage on the bottom bracket so that you can move the EBB. Then tighten up the grub screws. But not too tight, as reports here on MTBR say that overtightening the EBB grub screws can lead to a creaky EBB.

  3. #3
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    1. Loosen up the 2 set screws on the bottom of the BB shell.
    2. Place a screwdriver, allen key, or similar device in one of the holes in the side of the EBB through one of the windows in between the crankarms.
    3. Pedal forward with the screwdriver/allen key still in place. This will move the EBB. Pedal forward until you reach the desired chain tension.
    4. Too much tension? Pedal backwards.
    5. Once you get your chain to the desired tension, tighten set screws back up and remove screwdriver/allen key.
    6. Go ride!

  4. #4
    All day long
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    One thing I noticed on my Mary SS is that the chainring was not centered on the crank spider so I had a tight spot in the tension. I loosened the chainring bolts a little, turned the crank 90 degrees at a time and squeezed the chain together to get the chainring centered. Tightened it all up when I was done and now I don't have any tight/loose spots in the chain.

    After adjusting the chain tension as described by the previous posters, check to be sure your chain tension is consistant...if not, center the chainring.

  5. #5
    ridin' Mary
    Reputation: OhNooo's Avatar
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    Thanks Jill,

    I never saw those little holes in the drive side of the EBB before. That makes sense to use a hex-key as a lever against the crank arm spider. Much easier than the method I suggested of using a BB tool to put force on the BB bearings to move the EBB.

    This would be a great tip to have in a user manual. Unfortunately, the user's manual is dated 2004, and doesn't give anything more useful than "use a helmet or you will die".

  6. #6
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    Yeah, it's just a standard manual that comes with all bikes. But that's a great idea; I might look into getting a little EBB adjustment tag made up for the bikes. Or at least post something on our website.

    People often ask why we don't put "techy-er" info into the manual and unfortunately, much of the reason we (and many other manufacturers) don't is because of liability. Let's face it...even with the best instructions, some people just aren't mechanically inclined. Our biggest fear is that you start giving "how-to" instructions, people follow them unsuccessfully, and wind up either really messing up their bikes or getting hurt because they failed to adjust something correctly. Then they blame us, which could result in a lawsuit. Bummer it has to be that way, but much of today's society is all about not taking responsibility for your own actions.

  7. #7
    mtbr member
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    Thanks, worked like a charm.

  8. #8
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    Sweet!

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