Seatstay of frame is slightly bent... :(- Mtbr.com
Results 1 to 26 of 26
  1. #1
    mtbr member
    Reputation: TheGenTwo's Avatar
    Join Date
    Oct 2009
    Posts
    286

    Seatstay of frame is slightly bent... :(

    How? Here is a picture of the seatstay. There is a slight bend to it, around 0.5cm-1cm difference when I use a ruler.

    Image


    Image with lines showing bend. Look at the area where the lines end up being not parallel to the seatstay,



    Is this serious? The bend is only a slight bend and it does not affect tire clearance or anything. The left seatstay looks the same too. Im not sure whether this is just the geometry of the bike or a damage to the frame.

    I bought this commencal combi 2006 frame secondhand from another forumer locally if anyone would like to know.

    Im using this bike for XC purposes...Will it be fine to keep using it?

    EDIT: The left seatstay is not the same. The bend at the left is not as great as the right.
    Last edited by TheGenTwo; 10-31-2009 at 06:03 PM.

  2. #2
    mtbr member
    Reputation:
    Join Date
    Sep 2005
    Posts
    144
    Amateur opinion, I think you are alright. If both the seatstays have the same "slight" bend, it is probably designed. If it was accident/use related, the left and right seatstays would most likely not bend/snap/crack symmetrically. From my understanding, aluminum frames snap, they don't bend. I say keep riding, but would like to request release of liability if I am wrong and any subsiquent injury occurs due to frame failure.

  3. #3
    mtbr member
    Reputation: TheGenTwo's Avatar
    Join Date
    Oct 2009
    Posts
    286
    Quote Originally Posted by zazen
    Amateur opinion, I think you are alright. If both the seatstays have the same "slight" bend, it is probably designed. If it was accident/use related, the left and right seatstays would most likely not bend/snap/crack symmetrically. From my understanding, aluminum frames snap, they don't bend. I say keep riding, but would like to request release of liability if I am wrong and any subsiquent injury occurs due to frame failure.
    Ok sure thanks alot! Anyway before I made this thread I already decided to continue riding this frame as its only a slight bend.
    Do any of you think it might be due to the vbrakes Im using that are causing this bend(the pulling force on the brakes as the pads stop the wheel)? It seems quite unlikely as Im using normal mech vbrakes and not hydros...

  4. #4
    AZ
    AZ is offline
    banned
    Reputation: AZ's Avatar
    Join Date
    Apr 2009
    Posts
    19,198
    Looks like the seat stay rotated out of plane when it was built . As long as the dropouts are parellel and they should be if the wheel mounts up with no issues . No worries .

  5. #5
    mtbr member
    Reputation:
    Join Date
    Sep 2009
    Posts
    44
    Your good, no worries.

    If that is a steel frame, and if it bothers you, and you want to do something about it just use a rubber mallet and give it a couple of good wacks. I've done this many times when straightening out old Schwinn frames.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Jun 2008
    Posts
    863
    If both seat stays are bent identically I'm betting the bike was designed that way.
    Stache 7 --- Rigid Surly 1x1 B+ --- Dirt Drop CrossCheck

  7. #7
    Needed Less ~ Did More
    Reputation: Singlespeedpunk's Avatar
    Join Date
    Jan 2004
    Posts
    1,008
    I would say that if the wheel sits straight and level in the drop outs and is evenly spaced between the seat and chain stays don't worry. If only one of the stays was bent it would throw the wheel off line quite a bit at the tyre circumference.

    Another trick to check a frame is to hold a length of string on the left rear drop out, run it up around the head tube and down to the right rear drop out. Get a friend to measure the distance between the outer face of the seat tube and the string for any massive off-set.

    OK its not a granite allignment table but its easier to get hold of!

    SSP
    "Put any one on one of these singlespeed bikes and they could not help but have fun"
    -
    Otis Guy talking about klunkers c1976

  8. #8
    mtbr member
    Reputation: TheGenTwo's Avatar
    Join Date
    Oct 2009
    Posts
    286
    Thanks guys for all the input. Today I took out the ruler again and found out that the right seastay did not have as much as a bend as the left seatstay. Im going a lil crazy over this whole thing as it is my first real MTB. So it turns out both seatstays are not identical and this whole thing is probably a lil bit of frame damage.

    Still the wheel mounts up easily though about what SSP said, the wheel isnt evenly spaced between the two seatstays. However, the same thing occurs in the two chain stays as well. That means that the tire has around the same spacing at the right seatstay and chainstay. Same thing for the left seatstay and chainstay.

    And no, its not a steel frame otherwise I would have requested for my bike mech to do something about it.

  9. #9
    Birthday Collector
    Reputation: ATBScott's Avatar
    Join Date
    Jun 2006
    Posts
    2,603
    If the wheels are aligned and "centered" along the plane of the frame center, you should be fine. There is also a slight possibility that this may be designed in, as there could be "room" for a multi-speed cassette on that side and there is a slight difference in the dropouts? That is a guess - which brand/model of frame is this? I think it says "Commencal" on that seatstay? I know of them but little about them!
    R.I.P. Corky 10/97-4/09
    Disclaimer: I sell and repair bikes for a living


  10. #10
    mtbr member
    Reputation:
    Join Date
    Oct 2009
    Posts
    10
    If you are that worried about the frame take it to your mechanic and have him check it out.

  11. #11
    mtbr member
    Reputation: TheGenTwo's Avatar
    Join Date
    Oct 2009
    Posts
    286
    Quote Originally Posted by ATBScott
    If the wheels are aligned and "centered" along the plane of the frame center, you should be fine. There is also a slight possibility that this may be designed in, as there could be "room" for a multi-speed cassette on that side and there is a slight difference in the dropouts? That is a guess - which brand/model of frame is this? I think it says "Commencal" on that seatstay? I know of them but little about them!

    Its a Commencal Combi 2006 frame with 7005T6 aluminium.

    The freehub body of the wheel is longer than the disctab side of the wheel. This could explain why the tire is not entirely "spaced out"

    Here are pics to explain the above statements


    It may look misaligned but actually its rather straight. The freehub body side(the place where the cassette is fitted) is actually longer than the disc tab side of the hub. Maybe thats why the spacing between the tire and the two sides of the stays are not equal. Actually its also not that noticable until I fit my thumb in between to feel the difference.

  12. #12
    mtbr member
    Reputation: TheGenTwo's Avatar
    Join Date
    Oct 2009
    Posts
    286
    Some updates. I just finished my SS setup! I reinstalled the wheels and this time it came out looking almost centered.

    Updated pic



    Looking fine now... at least what I think.

  13. #13
    Out spokin'
    Reputation: Sparticus's Avatar
    Join Date
    Dec 1999
    Posts
    9,649
    Your rear wheel may not be correctly dished. Proper dishing will center the rim with the hub to accommodate the cassette.

    Your frame is fine. That bend is too insignificant to be of concern and may easily have come that way from the factory. Personally I would forget about it and enjoy the ride.

    --Sparty
    disciplesofdirt.org

    We don't quit riding because we get old.
    We get old because we quit riding.

  14. #14
    mtbr member
    Reputation: TheGenTwo's Avatar
    Join Date
    Oct 2009
    Posts
    286
    Quote Originally Posted by Singlespeedpunk
    I would say that if the wheel sits straight and level in the drop outs and is evenly spaced between the seat and chain stays don't worry. If only one of the stays was bent it would throw the wheel off line quite a bit at the tyre circumference.

    Another trick to check a frame is to hold a length of string on the left rear drop out, run it up around the head tube and down to the right rear drop out. Get a friend to measure the distance between the outer face of the seat tube and the string for any massive off-set.

    OK its not a granite allignment table but its easier to get hold of!

    SSP
    Ok I just did the string test on my bike. What I did was to round the string through the rear dropout, around the headtube. and then through the left drop out again. I got a friend to hold the two ends of the strings at the rear and left drop outs. I measured the distance of the string from the seattube where it crosses over. I measured it on both sides. Both were 45mm. What does this mean? Is my frame all right then? With no dents?

  15. #15
    I'm gonna have to kill ya
    Reputation: roybatty666's Avatar
    Join Date
    Mar 2009
    Posts
    321
    How does she ride?

    If she rides fine then forget about it

  16. #16
    mtbr member
    Reputation: TheGenTwo's Avatar
    Join Date
    Oct 2009
    Posts
    286
    Guys I did the string test today again. I tied a string at the right drop out, round it around the headtube. and then tied it to the left drop out. I used a metal rule to measure the distance from the string to the seattube.

    It measures at 35mm here.(right side)


    And measures at 33mm here.(left side)


    This is how I tied the string


    How the whole "string test" setup looked like


    So to conclude, the right side measures 35mm while the left side measures 33 mm.

    P.S: The bike rides ok and well! No sign of imbalance or anything . SS FTW.

  17. #17
    Birthday Collector
    Reputation: ATBScott's Avatar
    Join Date
    Jun 2006
    Posts
    2,603
    TheGenTwo, the 2mm difference is very likely the result of the way the string is tied to the dropouts - the proper way to do it is to remove the rear wheel, and then have the string run from the surface where the axle sits - since you are measuring from above this point, on the tube or forging's surface, it is quite likely that the string is off a tad. Main thing is if the bike feels like it tracks straight, the chain doesn't have a tendency to jump off the cogs, etc... you are probably fine. Enjoy the ride!
    R.I.P. Corky 10/97-4/09
    Disclaimer: I sell and repair bikes for a living


  18. #18
    mtbr member
    Reputation: TheGenTwo's Avatar
    Join Date
    Oct 2009
    Posts
    286
    1.The tire mounts up OK and is in centre with the frame
    2.The frame seems to ride well.. how would the feeling of imbalanced feel?
    3. Chain doesnt have a tendency to jump off my cog.
    4. String test seems to mean that my frame doesnt have any offset(considering that the 2mm is just due to the way the string is tied(different tension in tying))
    5. Bike mech in my shop says the bike is OK. Though he only spend around 10 seconds with it. He says its in its design, something about due to the "pedalling motion". I think he means that the chainstay design shortens the rear stays, making the bike go faster

    Anyway here is a pic of another Commencal I sourced from the web

    And this is mine


    Does the seatstays appear the same? Thanks alot folks!

  19. #19
    Out spokin'
    Reputation: Sparticus's Avatar
    Join Date
    Dec 1999
    Posts
    9,649
    You might be overthinking this... if it rides right, just ride it & love it...

    --Sparty
    disciplesofdirt.org

    We don't quit riding because we get old.
    We get old because we quit riding.

  20. #20
    one chain loop
    Reputation: fishcreek's Avatar
    Join Date
    Apr 2007
    Posts
    2,360


    question: is that a 73mm bottom bracket on a 68mm shell?
    everything sucks but my vacuum cleaner.

  21. #21
    mtbr member
    Reputation: TheGenTwo's Avatar
    Join Date
    Oct 2009
    Posts
    286
    Guys... bad news. I just measured my frame spacing and it turns out as 136mm instead of 135. Is it serious? And my tire isnt exactly spaced evenly between the stays. There seems to be a slight unevenness. By the way, when I mount the wheel, The stays will flex as a result of mounting a 135mm hub on a 136/137mm spacing.

    Sparty, the bike really rides fine but its these small details that's eating into me.

  22. #22
    Needed Less ~ Did More
    Reputation: Singlespeedpunk's Avatar
    Join Date
    Jan 2004
    Posts
    1,008
    The rear spacing being off 1mm is fine, the frame will flex to allow this.

    As to the frame being out 2mm along the whole length? Well thats not bad really! 2mm over 1000mm or what ever the frame measures is not significant.

    Put down the ruler and get out and ride

    SSP
    "Put any one on one of these singlespeed bikes and they could not help but have fun"
    -
    Otis Guy talking about klunkers c1976

  23. #23
    mtbr member
    Reputation: TheGenTwo's Avatar
    Join Date
    Oct 2009
    Posts
    286
    Quote Originally Posted by Singlespeedpunk
    The rear spacing being off 1mm is fine, the frame will flex to allow this.

    As to the frame being out 2mm along the whole length? Well thats not bad really! 2mm over 1000mm or what ever the frame measures is not significant.

    Put down the ruler and get out and ride

    SSP
    What about the fork ends being parallel? Mine arent really parallel... its abit off but overall the bike rides OK and I dont think theres any sign of being imbalance. Actually i have rode this bike for a few months already and it was only recently did I find these details...

  24. #24
    Feeling retro..but Jung
    Reputation: Germany_chris's Avatar
    Join Date
    Sep 2009
    Posts
    223
    +1 ssp

  25. #25
    one chain loop
    Reputation: fishcreek's Avatar
    Join Date
    Apr 2007
    Posts
    2,360
    dude, i think you have an OCD on measuring up things. ditch that measuring tape of yours and ride. for the fork ends not parallel, just loosen the stem and straighten it out. is one leg shorter than the other? is it gimp? if you worry too much, just sell your bike and buy a new one.

    btw, i worry more about your bottom bracket sizing more than anything.
    everything sucks but my vacuum cleaner.

  26. #26
    mtbr member
    Reputation: TheGenTwo's Avatar
    Join Date
    Oct 2009
    Posts
    286
    Quote Originally Posted by fishcreek
    dude, i think you have an OCD on measuring up things. ditch that measuring tape of yours and ride. for the fork ends not parallel, just loosen the stem and straighten it out. is one leg shorter than the other? is it gimp? if you worry too much, just sell your bike and buy a new one.

    btw, i worry more about your bottom bracket sizing more than anything.

    No.. its just the thought about the chance of something wrong being in my frame thats eating me up.

    I actually meant the rear frame ends actually.. not fork ends. When I mount up the wheels the stays will flex as I tighten the skewers. The stays are actually around 136mm/137mm long. My bike mech says that its OK though..

    I dont have the money for a new bike anyway.. thinking about it tonight.. i guess the frame is actually OK and since my riding is not affected, frame spacing is OK, "bents" in seatstay may actually be designed(like what my bike mech says too.)...

    About the bottom bracket. i really dont know. I just tried to tighten it and found that i couldnt tighten it further. have used it this way for a month or two already and nothing seems to have gone wrong...

Members who have read this thread: 0

Posting Permissions

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

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2019 VerticalScope Inc. All rights reserved.