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  1. #1
    Senior Member Reeses's Avatar
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    Skidded once on Sugino 75s, now it's making noises?

    I'm currently running SG75s with SG75 chainring and an RPM BB7420 bottom bracket (I'm aware that that's the incorrect spindle length for SG75 cranks). Anyways I was riding and did a few skids and now my drive train is making a really bad noise. It's like some sort of crunching sound every pedal stroke, like the sound of a really bad chain line. I've ridden with this setup for a couple weeks and had no problems until I did a few skid stops yesterday.

    So I took off my chain and spun the cranks. Judging by the chainring, the drive side crank is wobbling side to side (away and towards the frame). It's not the chainring, because I removed it and placed it flat on the ground and it didn't seem bent. I'll be pulling the crank off tomorrow to see if I'm f*ed, but right now I wanna know how this could have happened? I've skidded on $50 Vuelta Pista cranks with no problem for god's sake...

  2. #2
    Wear One IvyCap's Avatar
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    skidding has nothing to do with this. you probably set up your drivetrain wrong. chainline, spindle length, bolt torque, etc etc. The problem here isn't the cranks it's how you installed it. inspect the drivetrain everytime the crunching sound appears and check what seems to be out of line.

  3. #3
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    Sounds like a BB problem.

    Not a lot of possibilities if it's a fixed gear bike and a crunching noise.

  4. #4
    Senior Member Reeses's Avatar
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    Must I get the correct size bottom bracket? I checked my chainline and it looks near perfect. Or is there something more to it...

  5. #5
    Wear One IvyCap's Avatar
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    I think what leuky mentioned is correct. you are using a different type of spindle rather than the length of the spindle.
    this article should clarify: http://sheldonbrown.com/bbtaper.html

  6. #6
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    What did you check your chainline with? Are we talking about a tool, or just eye-balling it?

    I could say I tightened my stem bolts so they look perfectly even, so it's not gonna have issues. But a torque wrench would be a much more accurate option.

    And like Leukybear said, you gotta use a compatible BB with the cranks.

  7. #7
    Senior Member Reeses's Avatar
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    The thing is I rode it with no problems (and barely any sound) before, so maybe it was undertorqued? And Sheldon Brown says "I have a lot of experience mixing ISO/J.I.S. in both directions on my own personal bikes, and it as never given me a lick of trouble." and "In practice, you can very often get away with mixing these sizes, as long as you select a spindle length that gives the desired chainline."

    I took a tape measure to my chainring/seat tube and my chainline is off by 3 mm. Measured from the center of the seat tube to a tooth and got 45 mm
    Last edited by Reeses; 08-26-12 at 12:11 AM. Reason: more info

  8. #8
    Fresh Garbage hairnet's Avatar
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    Quote Originally Posted by Reeses View Post
    so maybe it was undertorqued?
    you said it

    wont know for sure until you use a torque wrench
    Quote Originally Posted by Scrodzilla View Post
    I'd rather ride a greasy bowling ball than one of those things.
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  9. #9
    Senior Member seau grateau's Avatar
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    Quote Originally Posted by Reeses View Post
    I'm currently running SG75s with SG75 chainring and an RPM BB7420 bottom bracket (I'm aware that that's the incorrect spindle length for SG75 cranks).
    Derp.
    Quote Originally Posted by adriano View Post
    thanckx.
    Quote Originally Posted by Nagrom_ View Post
    "I made love to your mother dozens of times last week, and she doesnt know what a worn chain ring looks like"

  10. #10
    Painfully average. calv's Avatar
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    Quote Originally Posted by Reeses View Post
    The thing is I rode it with no problems (and barely any sound) before, so maybe it was undertorqued? And Sheldon Brown says "I have a lot of experience mixing ISO/J.I.S. in both directions on my own personal bikes, and it as never given me a lick of trouble." and "In practice, you can very often get away with mixing these sizes, as long as you select a spindle length that gives the desired chainline."

    I took a tape measure to my chainring/seat tube and my chainline is off by 3 mm. Measured from the center of the seat tube to a tooth and got 45 mm
    Did Sheldon ever bust Mad skids like you did?
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  11. #11
    Senior Member Soo__Fuego's Avatar
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    Quote Originally Posted by calv View Post
    Did Sheldon ever bust Mad skids like you did?

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    Senior Member Spoonrobot's Avatar
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    Sounds like you didn't have the correct torque. Not a JIS/ISO issue.

    Correct torque specs are all over the map for 75s. Despite what the quote says, I'd recommend something like 28-33 ft/lbs since you've already biffed them once.

    Dear Mr. --

    Thank you very much for your e-mail.

    The torque is 12-16N.m.
    However, this torque specification is appropriate
    under the condition that the SG75 cranks are used with the NJS parts.

    We recommend to grease the BB spindle slightly
    to prevent seizing and rust on the spindle.

    We also recommend to do maintenance periodically.

    Best regads,
    Yuki Iwai
    SUGINO CYCLE INDUSTRIES, LTD.
    iwai@suginoltd.co.jp
    TEL. +81-(0)742-62-5311
    FAX.+81-(0)742-62-5320
    287-1 Tohkujo-cho, Nara, Japan 630-8144

  13. #13
    Senior Member Reeses's Avatar
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    I removed the cranks and BB and reinstalled everything with sufficient torque but the chainring/crankarm still wobbles side to side.

  14. #14
    Blaster of Reality Scrodzilla's Avatar
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    Sounds like either the square taper interface is damaged or the BB is crap.

  15. #15
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    Quote Originally Posted by Reeses View Post
    I removed the cranks and BB and reinstalled everything with sufficient torque but the chainring/crankarm still wobbles side to side.
    still using the incorrect bb?

  16. #16
    Senior Member Reeses's Avatar
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  17. #17
    Blaster of Reality Scrodzilla's Avatar
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  18. #18
    Senior Member Reeses's Avatar
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    Currently I'm trying to work a stripped crankarm off of a Sugino 75 BB so I can use the correct size bottom bracket.

  19. #19
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    Timely topic.

    I run a freewheel on my TimeLine, so no skid stops. I do ride over the local bridges and some hills in the area. I've been doing more and more hill rides lately. I don't stand and mash when I climb, but maybe the spate of climbing over the last three weeks has something to do with today's problem. I rode over the Brooklyn Bridge to the Greenway and up to 44th Street: No problems until, on the way back, this really annoying squeaking started coming from my bottom bracket. It sounded almost like shoes on a basketball court.

    The crank arms and pedals look okay, so I'm guessing the BB needs to be lubed and torqued. Since I don't have a torque wrench, I'll take it up to the LBS this week.

  20. #20
    Blaster of Reality Scrodzilla's Avatar
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    Cool story bro.

    For what it's worth, "mashing" is not standing up and pedaling like a rabid gorilla. To "mash" simply means to push a big gear ratio.

  21. #21
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    Quote Originally Posted by Scrodzilla View Post
    Cool story bro.

    For what it's worth, "mashing" is not standing up and pedaling like a rabid gorilla. To "mash" simply means to push a big gear ratio.
    Yup. Thanks for the reminder. To clarify, I do run the stock gearing, which is pretty big (46/15). What I meant to say was that while I do mash in the sense of the big gear, I climb seated. Sorry about the misuse of terms .

    This actually belongs in the Ask Scrod thread (so, sorry again for the mis-post; please move at your discretion, Mr. Scrodmerator), but does this sound like a matter of lube the BB and re-torque it, or is it likely that my stock BB is toast? I've read elsewhere on the board that a few people have had issues with the BB on The Hour, which I believe is the same on the TimeLine.

    "To stand up and pedal like a rabid gorilla, or to sit and spin like a gerbil on crack? That is the question..."

  22. #22
    Senior Member Bat56's Avatar
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    Great hijack. Lube the BB and re-torque it... Do you know what you are talking about?

  23. #23
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    He must mean grease the threads and install it to the right torc speques

  24. #24
    Senior Member
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    Quote Originally Posted by BigglyPuff View Post
    He must mean grease the threads and install it to the right torc speques
    Yup. Thanks. Sorry for the thread hijack.

  25. #25
    Senior Member Reeses's Avatar
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    Today I tried to separate the stripped SG75 crank from the SG75 bottom bracket - it did not go well. But in curiosity I attached the drive side SG75 I skid on a couple days ago onto the non drive side of the BB and put the chainring on it. I gave it a spin and the wobble was gone. I guess it was that cheap RPM BB that I trashed and not the crank arm, thank goodness.

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