Advertise on Bikeforums.net



User Tag List

Page 1 of 2 12 LastLast
Results 1 to 25 of 38
  1. #1
    Senior Member
    Join Date
    Oct 2008
    Posts
    2,930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Chain Ring Rubbing Chain Stay

    I changed the chain rings on my bike recently. I put a 47T inner ring on in place of the 42T that was on it. The thing is, it is very close to the chain stay (~1mm) and if the frame flexes (accelerating, cornering, etc) that ring will scrape the chain stay. Yes, the bike has a very tight rear triangle.

    Is there any way to shim the spindle-crank interface to move the rings outboard a bit. I did some calculations and a 0.004" shim will move the rings 0.125" outboard. I'm sure that would do the job.

    I tried a copper shim but it is too soft. It extrudes out of the way when crank is tightened. Should I use aluminum foil, stainless steel shim stock or what? Does anyone make a pre-formed shim for this? How do you hold the shim in place as the crank is installed?

    Is shimming the wrong way to go with this problem?

  2. #2
    Senior Member Unapomer's Avatar
    Join Date
    Nov 2008
    Location
    Left Coast, U.S. of A.
    Posts
    52
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Headset spacers for 1" headset will fit (file the tit off the inside diameter of the spacer) between the fixed cup and the bottom bracket shell, thus moving the spindle further outboard. The adjustable left side cup will compensate by adjusting accordingly. Of course this works if you have an old style BB.

  3. #3
    Senior Member Coyote2's Avatar
    Join Date
    Sep 2005
    Posts
    2,393
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I presume this is a SS or FG bike, otherwise I can't imagine why you would have a 47t chainring. If this presumption is correct, why not just stick with the 42t and put on a smaller cog?

    PS: I saw you guys at Red Rocks in '04...A really good show. Or are you not that Mike Mills?

  4. #4
    mechanically sound frankenmike's Avatar
    Join Date
    Jan 2007
    Location
    Dover, NH
    My Bikes
    rigid 29er moto, s-works stumpjumper fsr,black fixie,masi roadbike, ugly old hardrock commuter
    Posts
    1,260
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The shimming you're describing is definitely not the way to go. A better place to shim, as unapomer pointed out, is between the bb cup and the frame. You can get spacers meant for this area, also there are certain spacers from other components that will work. Not sure a 1" headset spacer would fit, but if all else fails you can get a spacer from your lbs for under a buck. I used a freewheel spacer for mine- worked well.

  5. #5
    Senior Member
    Join Date
    Aug 2005
    Location
    Pittsburgh, PA
    My Bikes
    '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
    Posts
    26,180
    Mentioned
    14 Post(s)
    Tagged
    0 Thread(s)
    The other option is a bottom bracket with a longer spindle. DO NOT shim the square taper itself. Either add a spacer under the drive-side cup or get a different bottom bracket.

  6. #6
    Senior Member
    Join Date
    Oct 2008
    Posts
    2,930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I have my own reservations about shimming. Why do you think shimming is a bad idea?

    The bottom bracket is a Phil Wood. It has already been set to the left about as far as I am comfortable doing - the left retaining ring is flush with BB shell, the right retaining ring protrudes two full turns of the threads, approx. 0.05".

    IIRC, the spindle is 120 mm long with a two degree taper. The bottom bracket shell is 68 mm wide.

    I am not averse to buying a new Phil BB with a longer spindle but they do cost $200. What I worry about with that option is spending the cash but not solving the problem. After all, we are talking about only 0.004" difference.

    I think the next step i to ensure the chain rings and freewheel are properly aligned.

    Could it be a crank problem? Is the square-sided socket mis-shapen, stretched or something? It is a vintage Campagnolo NR crank but is new to me (my first use of this crank). Could it be a different taper than my spindle?

    What should I do after that?

  7. #7
    Senior Member Unapomer's Avatar
    Join Date
    Nov 2008
    Location
    Left Coast, U.S. of A.
    Posts
    52
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Sure, the taper in the crank arm could be stretched out some, causing the crank arm to sit a little closer to the BB shell. But the way I see it, based on what you are saying, is that you replaced a 42 inner ring with a 47 as your inside chainring and before you did that, the 42 cleared the chainstay, right ?? The larger outside dimension (o.d.) of the 47 is too close to the chainstay, which makes sense because the chainstay ANGLES out from the BB shell to the rear dropout. So, you need to move the right crankarm away from the BB shell .125 Therein lies the crux of the problem ? Putting a shim inside the taper of the crank arm might be acceptable for a fix in a third world country, but it will be temporary at best and a lousy way to try and solve the problem. First and foremost (as you previously said) is what does the chailine look like ?? Let's go from there, and is there any other info you didn't tell us in your two previous posts ?
    "Win if you can, lose if you must, but always cheat" 'Classy' Freddie Blassie

  8. #8
    Senior Member
    Join Date
    Oct 2008
    Posts
    2,930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    "...third world country..." LOL!

    In my business we use shims all the time to align things. Sometimes they are rigid shims (sheet metal or foils) sometimes they are liquid shims (metal powder-filled epoxy) that harden to retain the location.

    I am concerned about shimming here because it is a mechanically powered interface, so I understand the comments above.

    Here is a set of questions regarding moving the bottom bracket cartridge with the bottom bracket shell. What is the minimum recommended thread engagement between the retaining ring and the bottom bracket shell? How many threads, as a minimum, need to be engaged? How far out can I allow the retaining ring to protrude?

  9. #9
    Senior Member Unapomer's Avatar
    Join Date
    Nov 2008
    Location
    Left Coast, U.S. of A.
    Posts
    52
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    If you're concerened about shimming on the right with less thread engagement on the left, why not consider having your LBS use a BB facing cutter to face off about .010 or so(or however much you need to keep thread engagement safe) on the left ? Is that a viable solution ?
    "Win if you can, lose if you must, but always cheat" 'Classy' Freddie Blassie

  10. #10
    cab horn
    Join Date
    Jun 2004
    Location
    Toronto
    My Bikes
    1987 Bianchi Campione
    Posts
    28,295
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Mike Mills View Post
    "...third world country..." LOL!

    In my business we use shims all the time to align things. Sometimes they are rigid shims (sheet metal or foils) sometimes they are liquid shims (metal powder-filled epoxy) that harden to retain the location.

    I am concerned about shimming here because it is a mechanically powered interface, so I understand the comments above.

    Here is a set of questions regarding moving the bottom bracket cartridge with the bottom bracket shell. What is the minimum recommended thread engagement between the retaining ring and the bottom bracket shell? How many threads, as a minimum, need to be engaged? How far out can I allow the retaining ring to protrude?
    Phil wood specs +/- 5mm for retaining rings. If you need to "adjust" it more then you either have

    1) ****ed up crank
    2) wrong length bb for said crank

    The other option, if you have a steel frame and the chainstay is not dimpled already is to PUT one there. A light whack with the hammer will most likely give you the clearance you need - assuming you've verified that the bb length is correct and that you've done everything else possible to make it clear the chainstay without resorting to this method.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  11. #11
    Senior Member
    Join Date
    Oct 2008
    Posts
    2,930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I went to the Phil Wood web site and read the installation instructions. It says the retaining ring design allows for protrusions of up to 5 mm (0.20")!!!

    Mine might be different than what he is currently selling. I bought this very soon after he first started to marketed them (~1974). When I bought it, it did not have instructions (that I recall).

    It seems I am at the point where it has to be removed for inspection and then re-installed. I am loathe to do that as I know it has thread locker on it. I just don't recall which type. I am worried. Is there a universal solvent for thread locker, perhaps even a Loc-Tite thread locker product?
    Last edited by Mike Mills; 11-07-08 at 03:02 AM.

  12. #12
    Senior Member
    Join Date
    Oct 2008
    Posts
    2,930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I installed a thin copper shim giving about 1.5 mm clearance. I checked the chain line using a long straight edge. The inner chain ring is aligned with the third of six rear sprockets on an Ultra-6 freewheel (120 mm rear dropout spacing). That sounds about right, doesn't it, or is it off?

    If that is reasonable, I will consider replacing the copper shim with aluminum or stainless steel foil.

    Any ideas on a solvent for the thread locker?

  13. #13
    Senior Member
    Join Date
    Aug 2005
    Location
    Pittsburgh, PA
    My Bikes
    '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
    Posts
    26,180
    Mentioned
    14 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Mike Mills View Post
    Any ideas on a solvent for the thread locker?
    Acetone will dissolve Loctite.

  14. #14
    Surf Bum
    Join Date
    Aug 2008
    Location
    Pacifica, CA
    My Bikes
    Vintage Trek, Vintage Diamond Back Mountain Bike, Bianchi Axis CrossBike
    Posts
    2,011
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Mike Mills View Post
    I am not averse to buying a new Phil BB with a longer spindle but they do cost $200.
    I'm pretty sure you can buy spindles separately, so the cost would not be too outrageous.

  15. #15
    Senior Member
    Join Date
    Dec 2004
    Location
    Athens, Ohio
    My Bikes
    Custom Custom Custom
    Posts
    5,104
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    take a C-clamp and put a dimple in the chainstay. No one will be able to tell since its behind the chainring. Yes it will probably dimple the other side of the stay as well but it will look cleaner than taking a punch and hammering away at the stay.

  16. #16
    Senior Member
    Join Date
    Aug 2005
    Location
    Pittsburgh, PA
    My Bikes
    '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
    Posts
    26,180
    Mentioned
    14 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by nitropowered View Post
    take a C-clamp and put a dimple in the chainstay. No one will be able to tell since its behind the chainring. Yes it will probably dimple the other side of the stay as well but it will look cleaner than taking a punch and hammering away at the stay.
    If you go this route, put a piece of wood on the inside of the chainstay before you apply the c-clamp and pad the c-clamp's jaws with tape. The wood will distribute the force over the inside of the stay and keep it from denting on that side and the tape should protect the paint where you make the "dimple".

  17. #17
    Senior Member Unapomer's Avatar
    Join Date
    Nov 2008
    Location
    Left Coast, U.S. of A.
    Posts
    52
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Good suggestions by nitropowered and HillRider, I've done that a few times myself. As for the threadlocker issue, heat is your friend here. Use a heatgun on that BB shell and keep us posted on how everything works out.
    "Win if you can, lose if you must, but always cheat" 'Classy' Freddie Blassie

  18. #18
    Senior Member
    Join Date
    Oct 2008
    Posts
    2,930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by HillRider View Post
    Acetone will dissolve Loctite.
    Thanks for that news. I thought it might. I'll try that first.

  19. #19
    Senior Member
    Join Date
    Oct 2008
    Posts
    2,930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by nitropowered View Post
    take a C-clamp and put a dimple in the chainstay. No one will be able to tell since its behind the chainring. Yes it will probably dimple the other side of the stay as well but it will look cleaner than taking a punch and hammering away at the stay.
    I forgot to respond to this recommendation (line of thinking). I really would not want to do this. That's probably why I did not respond sooner - I put it out of my mind. I think I'd prefer to go back to a 42T chainring rather than to "crunch" the tube. I am so averse to this, I'd prefer to buy a new BB cartridge ($200) than do this.

    Right now, my preference is to move the BB cartridge outboard. I have to break the thread locker bonds to do this but it seems the right way to go. I have about 1mm of clearance right now. If I can get another 1 mm (2 mm total), I'd say I was done with this exercise.

    BTW, is there a recommended amount of clearance between the chainring and the stay? I'm guessing at 2 mm to afford some room for flexing/bending (dynamics).

  20. #20
    Senior Member
    Join Date
    Oct 2008
    Posts
    2,930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I took my entire bottom bracket apart today to work on this "problem".

    The Phil Wood bottom bracket has been in this bike, unattended, for more than 30 years and it is still FLAWLESS! That is called, "getting your money's worth".

    To work on the chaing ring to stay spacing problem, I installed the drive side bottom bracket lock ring to it's minimum depth leaving a full 5 mm / 0.20" protrusion (allowed per instructions on Phil Wood's web site). This allows the cartridge to protrude the maximum allowable amount and maximizes the clearance between the ring and the stay. In this configuration I have 0.125" clearance which is more than enough. I am happy again.

    I may or may not adjust the cartridge inboard a smidge as the large chain ring lines up with the second of the six rear cogs.


    I am also pursuing the shim idea. If I get anywhere with it, I will show you the process and the product. Please remind me again, what is wrong with using a properly designed and installed shim?

  21. #21
    Senior Member
    Join Date
    May 2008
    Location
    Beverly Hills, MI
    My Bikes
    '72 Fuji Finest, '06 Fuji Team Issue, '06 Salsa Las Cruces, Nashbar Frame single speed
    Posts
    544
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Mike Mills View Post
    Please remind me again, what is wrong with using a properly designed and installed shim?
    If I understand your question, you are suggesting that you shim between the crank and the axle? That's not necessarily a bad idea, it's just difficult to do right because the crank and axle use an interference fit via the matching tapers. The only way of properly shimming this would be to either insert 4 separate flat shims (one for each face of the taper), or to construct a tapered "box" or "hat" to fit over the end of the axle. The first method is doable, but tedious, and the second method would require quite a bit of work, I would think. So, to answer your question directly, there would be nothing wrong with using a "properly designed and installed" shim, the trick is in the doing.
    Doug

    '72 Fuji Finest
    '06 Fuji Team Issue
    '06 Salsa Las Cruces
    Nashbar Single Speed

  22. #22
    Senior Member
    Join Date
    Oct 2008
    Posts
    2,930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Doug,

    I understand your point. Great minds think alike.

    Here is a flat-pattern sketch of the shim I made and installed. The central cruciform structure holds the four leaves together and prevents friction form skewing the leaves during installation.

    To use it, you place it on the end of the spindle and temporarily hold it in place with a crank bolt through the central hole while you "fold on the dotted lines". Each of the four arms folds down along the square, tapered bottom bracket spindle. You remove the bolt and install the crank over the newly formed shim. As you install and tighten the crank bolt, the four arms of the shim cinch down against the spindle.



    I made one from 0.009" thick aluminum. The five holes were punched not drilled. The central hole was opened up with a conical Dremel grinder bit. It was not drilled because the foil is too thin. I installed it and it worked beautifully on the very first try. Remember, this is a foil, so you cut it freehand with a scissors. Total time invested in design, fabrication and installation was about 15 - 30 minutes.

    All is well in again.

    Quote Originally Posted by dperreno View Post
    ...the trick is in the doing.
    DONE!
    Last edited by Mike Mills; 11-16-08 at 07:04 PM.

  23. #23
    I live in a bicycle. smovlov's Avatar
    Join Date
    Apr 2008
    Location
    FLOR-DUH
    My Bikes
    1980 Motobecane Le Champion, 1972 Schwinn Super Sport, 1985 Nishiki Cresta GT
    Posts
    231
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I could be wrong here but the shim might compress out over time and would consequently (as we say in the south) "waller" out the crank. Can someone verify this? I would think a harder metal than aluminum would be in order.
    I think further therefore I go farther.
    1979 Motobecane Le Champion, 1972 Schwinn Super Sport, 1985 Nishiki Cresta GT

  24. #24
    Senior Member
    Join Date
    Oct 2008
    Posts
    2,930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I looked for stainless steel shim stock but haven't found any yet.

    The aluminum shim stock is as hard as the crank itself. I gave it a try. Fear not, I will be watching it carefully.

  25. #25
    Passista Reynolds's Avatar
    Join Date
    Jul 2005
    My Bikes
    1998 Pinarello Asolo, 1992 KHS Montaņa pro, 1980 Raleigh DL-1, IGH Hybrid, IGH Utility
    Posts
    4,641
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Mike Mills View Post
    I have my own reservations about shimming. Why do you think shimming is a bad idea?

    The bottom bracket is a Phil Wood. It has already been set to the left about as far as I am comfortable doing - the left retaining ring is flush with BB shell, the right retaining ring protrudes two full turns of the threads, approx. 0.05".

    IIRC, the spindle is 120 mm long with a two degree taper. The bottom bracket shell is 68 mm wide.

    I am not averse to buying a new Phil BB with a longer spindle but they do cost $200. What I worry about with that option is spending the cash but not solving the problem. After all, we are talking about only 0.004" difference.

    I think the next step i to ensure the chain rings and freewheel are properly aligned.

    Could it be a crank problem? Is the square-sided socket mis-shapen, stretched or something? It is a vintage Campagnolo NR crank but is new to me (my first use of this crank). Could it be a different taper than my spindle?

    What should I do after that?
    A Shimano taper crank on a Campagnolo taper spindle will go "deeper" than a Shimano/Shimano set, and vice-versa.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •