Bicycle Mechanics - Crank/ chain stay clearance issues

Hi grouppe-

I’m a somewhat recently new road cyclist who has learned a lot from browsing the forums…Thanks. I recently purchased a used 2003 Cannondale R600 that has had its drivetrain upgraded to Dura-Ace 7700?…I think.

I bought a Cateye computer that has wireless speed and cadence. The unit has an “arm” for sensing speed and another one for sensing cadence. My problem is that when I mount the unit I do not have enough clearance between the outside of the chain stay (where the cadence transmitter mounts), and the inside of the left crank arm. I also need to attach the magnet to the crank arm which will make the clearance issue even worse. The clearance between the crank arm and the chain stay is about the width of a dime without anything mounted. Is this amount of clearance normal? There is a lot more space for the right side crank arm. I’m also having front derailleur issues as well. I have a triple. When shifting from the top chain ring it will only go to the smallest ring and not the middle. When shifting up, it works fine.

Is it possible that I could have an incorrect or misaligned bottom bracket causing these clearance and shifting problems?

Thanks in advance and sorry for the long post.

Steve

Hi grouppe-

I’m a somewhat recently new road cyclist who has learned a lot from browsing the forums…Thanks. I recently purchased a used 2003 Cannondale R600 that has had its drivetrain upgraded to Dura-Ace 7700?…I think.

I bought a Cateye computer that has wireless speed and cadence. The unit has an “arm” for sensing speed and another one for sensing cadence. My problem is that when I mount the unit I do not have enough clearance between the outside of the chain stay (where the cadence transmitter mounts), and the inside of the left crank arm. I also need to attach the magnet to the crank arm which will make the clearance issue even worse. The clearance between the crank arm and the chain stay is about the width of a dime without anything mounted. Is this amount of clearance normal? There is a lot more space for the right side crank arm. I’m also having front derailleur issues as well. I have a triple. When shifting from the top chain ring it will only go to the smallest ring and not the middle. When shifting up, it works fine.

Is it possible that I could have an incorrect or misaligned bottom bracket causing these clearance and shifting problems?

Thanks in advance and sorry for the long post.

Steve The DA triple crank is supposed to have a 118.5 BB spindle. Only way to know if yours is right is to pull it and measure. The shifting most likely a derailer adjustment or alignment issue, assuming all the correct parts were used in the upgrade.

If your inner chainring clears the chainstay by more than a couple of mm, your BB may be mounted too far to the right. I am not familiar with the inner guts of DA, but both of my Campag. cartridge BBs have narrow shims which could be juggled to fine-tune the chainline.

To check your BB shell alignment, first center your rear wheel as well as possible between the chainstays, then measure the distance from each side of the BB spindle to the rear axle. If the spindle is not parallel to the axle, you do have a problem.

If your inner chainring clears the chainstay by more than a couple of mm, your BB may be mounted too far to the right. I am not familiar with the inner guts of DA, but both of my Campag. cartridge BBs have narrow shims which could be juggled to fine-tune the chainline.
A 'couple of mm' is minimum. It could be more and not be a problem with the BB at all.The simple answer is that a given crankarm/BB will have varyng clearance depending on the chainstay design even when everything else is right....But after re-reading how much clearance he actually has,it doesn't sound normal.If his BB isn't noticably shimmed on the drive side, and the spindle is 118.5,then he is stuck with what he's got.

Thanks for the info. The inner chain ring bolts clear the chain stay by no more than half the width of a dime...almost looks like its rubbing, but it's not. ( but it's the other side I'm having the issue with) Should the distance between the crank arm and the chain stay on both sides be the same?

Thanks for your comments

Thanks for the info. The inner chain ring bolts clear the chain stay by no more than half the width of a dime...almost looks like its rubbing, but it's not. ( but it's the other side I'm having the issue with) Should the distance between the crank arm and the chain stay on both sides be the same?

Thanks for your commentsYou can ask questions all day and everyone can take a guess. Pull the crank arms and measure the spindle length.It should be 118.5 for the DA triple.

You can ask questions all day and everyone can take a guess. Pull the crank arms and measure the spindle length.It should be 118.5 for the DA triple.

Yup. Sometimes one measurement is worth a thousand guesses.