Advertise on Bikeforums.net



User Tag List

Page 1 of 2 12 LastLast
Results 1 to 25 of 29
  1. #1
    Senior Member
    Join Date
    Apr 2011
    Location
    Clarkston, MI
    My Bikes
    Mongoose, Trek 3700, Trek 7200
    Posts
    54
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Trek 3700 with 3 broken axles

    Before I begin, this is the bike I'm talking about:


    During this past week, I've broken(snapped) 1 axle, and bent 2 new ones.
    The local bike shop has now refused to give me new ones, saying that I need a new type of wheel with a cassette axle. Runs about $50 - $85, not outrageous(?), but a lot for an unemployed student.
    I should note that the first axle was the first axle the bikes seen, and lasted maybe 600 miles. The 2 bent axles lasted maybe 3 each. I'm not offroading, but each of the new axles I used for a pretty aggressive hill climb, and broke as soon as I got to the top.
    History:
    This bike has had a badly bent frame, the local shop fixed it a few years ago, and it's been fine since.
    This bike spent the winter in the bike shop storage, because the chain broke 8 miles from my house. The bike shop said it was due to a bent hanger, which they fixed.
    After the first new axle bent, they kept it overnight to look it over. They said the frame was still true and they didn't see any problems with it.
    So, should I upgrade to the new axle, or is there a special type of axle that won't break when I use it? I should also mention that the new axle was a temporary fix. They recommended I get a dual suspension bike, to the tune of $1200 - 1500. I'd like to eventually do that, but being an unemployed student prevents it.

    Also, before I posted I noticed VERY descriptive titles. I'm new to this website and to other people that care about bikes. If I made this in the wrong section, please let me know

  2. #2
    Senior Member
    Join Date
    Apr 2011
    Location
    Clarkston, MI
    My Bikes
    Mongoose, Trek 3700, Trek 7200
    Posts
    54
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Reading the stickies, I should also include:
    This bike is fairly new, not more than 5 years old. I'd guess about 2007.
    This is a 21 speed, with 3 on the front and 7 on the back. Not sure of a better way to say that
    No BMX, mostly ride on sidewalks or packed gravel. Occasionally I'll ride on a rough path, but I get no air. I usually just get stuck

  3. #3
    Senior Member mrrabbit's Avatar
    Join Date
    Dec 2007
    Location
    San Jose, California
    My Bikes
    2001 Tommasini Sintesi w/ Campagnolo Daytona 10 Speed
    Posts
    3,180
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Check the dropout alignments. Putting new axles and wheels in place of failed one that suffered bent or broken axles WITHOUT checking dropout alignment is the same as tossing good money after bad.

    If it turns out the dropouts are out of alignment - and the LBS has been doing the replacement work for you - either light a fire under their ass or find another LBS!!!

    =8-)

    (Dropout alignment tools look like T-Handles with adjustable cups on the ends...)

    =8-)
    4000+ wheels built since 1984...

    Disclaimer:

    1. I do not claim to be an expert in bicycle mechanics despite my experience.
    2. I like anyone will comment in other areas.
    3. I do not own the preexisting concepts of DISH and ERD.
    4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
    5. My all time favorite book is:

    Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life

  4. #4
    Senior Member
    Join Date
    Apr 2011
    Location
    Clarkston, MI
    My Bikes
    Mongoose, Trek 3700, Trek 7200
    Posts
    54
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Drop out alignment info can be found in the stickies?

  5. #5
    Senior Member
    Join Date
    Sep 2004
    Location
    boston, ma
    Posts
    2,806
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    if they said dropout alignment is fine and you are still breaking axles then get something better than a freewheel hub. i bet you are overweight or thrash on the bike hard

  6. #6
    Senior Member RavingManiac's Avatar
    Join Date
    Jun 2010
    Location
    Maine
    My Bikes
    90 Raleigh Chill MTB, 92 Trek 1200, 2004 Trek 2300, 67 Sports, 70 Sports, 71 Philips, Lotus Challenger, 74 Super Course, Univega Gran Tourismo, Nishiki Seral
    Posts
    552
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I doubt that bike has a freewheel hub. You say it had a badly bent frame and they fixed it. Aluminum frames aren't generally the best candidates for frame straightening if badly bent. I'd try a different shop.

  7. #7
    Senior Member mrrabbit's Avatar
    Join Date
    Dec 2007
    Location
    San Jose, California
    My Bikes
    2001 Tommasini Sintesi w/ Campagnolo Daytona 10 Speed
    Posts
    3,180
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Dropout alignment is simply the process of making certain that the dropout faces are perfectly parallel with each other. This ensures that the load placed on the axle when installing the wheel is linear or in line with the axle - not at an angle.

    Basically, you are making sure that the bicycle itself is not doing anything detrimental to the axles...so that the only detrimental loads placed on the bike and parts is that which YOU AS THE RIDER place on the bike when using it.

    When the bike is aligned properly and parts continue to break - then you know that either you need better quality parts OR a bike built to handle someone like yourself.

    =8-)
    4000+ wheels built since 1984...

    Disclaimer:

    1. I do not claim to be an expert in bicycle mechanics despite my experience.
    2. I like anyone will comment in other areas.
    3. I do not own the preexisting concepts of DISH and ERD.
    4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
    5. My all time favorite book is:

    Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life

  8. #8
    Senior Member
    Join Date
    Jul 2006
    Posts
    425
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Not to get too personal, but how much do you weigh? Are they all rear axles? From your first post, you mention "cassette axle". Do you have a cassette rear hub? Threaded hubs don't have as much axle support. Cassette hubs have better axle support (the bearings are further to the outside).

  9. #9
    Senior Member
    Join Date
    Apr 2011
    Location
    Clarkston, MI
    My Bikes
    Mongoose, Trek 3700, Trek 7200
    Posts
    54
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by reptilezs View Post
    if they said dropout alignment is fine and you are still breaking axles then get something better than a freewheel hub. i bet you are overweight or thrash on the bike hard
    I occasionally ride hard, but the 2 bent axles broke on a 3 mile all paved route. If that's hard, then I need a bike made out of titanium!

    Quote Originally Posted by RavingManiac View Post
    I doubt that bike has a freewheel hub. You say it had a badly bent frame and they fixed it. Aluminum frames aren't generally the best candidates for frame straightening if badly bent. I'd try a different shop.
    Not sure what a free wheel hub is, I haven't had a chance to read the guides the stickies are recommending. It wasn't mangled like a pretzel, but the back frames bars were touching the tire if I remember correctly.

    Quote Originally Posted by mrrabbit View Post
    Dropout alignment is simply the process of making certain that the dropout faces are perfectly parallel with each other. This ensures that the load placed on the axle when installing the wheel is linear or in line with the axle - not at an angle.

    Basically, you are making sure that the bicycle itself is not doing anything detrimental to the axles...so that the only detrimental loads placed on the bike and parts is that which YOU AS THE RIDER place on the bike when using it.

    When the bike is aligned properly and parts continue to break - then you know that either you need better quality parts OR a bike built to handle someone like yourself.

    =8-)
    I was hoping I'd need better quality parts, because the first axle had about 90 miles on it this season before it broke, and last season it was my daily rider. If the last axle could last that long, then the new axles that bend after 3 miles must be inferior parts, right?

    Quote Originally Posted by krome View Post
    Not to get too personal, but how much do you weigh? Are they all rear axles? From your first post, you mention "cassette axle". Do you have a cassette rear hub? Threaded hubs don't have as much axle support. Cassette hubs have better axle support (the bearings are further to the outside).
    240 lbs. All rear axles. Not sure if it matters, but if I'm in 6th or below and start off the front of the bike will do a wheelie. I think when I was doing those hill climbs and shifted into those lower gears it caused too much stress to the axle. All 3 broke when I was going up hills. The current axle/hub combo places stress right at the edge of the wheel. The new wheel/axle/hub the store recommended moved the stress out past the gears right next to the frame.

    When the axles bent/broke, they all caused the tire to rub against the frame. Particularly when I peddled.
    This is one of the trips that broke the axle.

  10. #10
    Constant tinkerer FastJake's Avatar
    Join Date
    May 2010
    Location
    Madison, Wisconsin
    Posts
    6,122
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    It's definitely possible you have a freewheel, and not a cassette. I've seen some newer (post 2000) name brand MTBs with 7-speed freewheels. This is important in diagnosing your problem. Figure out which one you have, they are not the same: http://www.sheldonbrown.com/free-k7.html

    If you have a freewheel then I strongly recommend switching to a rear wheel with a Freehub and cassette as your bike shop might have recommended. This should solve your broken axle problems. The 7 speed freewheel has a long section of unsupported axle causing it to fail with even lightweight riders.
    Why "derailer" is the correct way to spell the gear-change mechanism: sheldonbrown.com/derailer.html

  11. #11
    Quirky Grifter LesterOfPuppets's Avatar
    Join Date
    Sep 2008
    Location
    Vancouver, USA
    My Bikes
    My War
    Posts
    20,069
    Mentioned
    43 Post(s)
    Tagged
    7 Thread(s)
    Most 7-speed setups these days are freewheels. The 2009 specs mention Sunrace 13-34. As far as I know Sunrace only makes freewheels.

    The bike is definitely a 2007 and I'm pretty sure it's a freewheel rear hub.
    1980ish Free Spirit Sunbird fixed * 1996 Mongoose IBOC Zero-G * 1997 KHS Comp * 1990-ish Scapin * Lemond Buenos Aires Triple

  12. #12
    Senior Member
    Join Date
    Apr 2011
    Location
    Clarkston, MI
    My Bikes
    Mongoose, Trek 3700, Trek 7200
    Posts
    54
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Ok, I currently have the one on the left, and the bike shop recommended the one on the right. I'll go with that, but it puzzles me that the first axle lasted so long, and the next 2 broke so fast.

  13. #13
    Quirky Grifter LesterOfPuppets's Avatar
    Join Date
    Sep 2008
    Location
    Vancouver, USA
    My Bikes
    My War
    Posts
    20,069
    Mentioned
    43 Post(s)
    Tagged
    7 Thread(s)
    I remember back in my freewheel MTB days that most replacement axles were pretty weak. The average replacement was $5, but you had to pay $10-15 for the strong stuff (1988-1991 prices.) The stock axle on the Trek was probably a good one but replacements were inferior.

    I haven't taken my Trek 4000 with 7-sp freewheel out on the gnar trails yet. Knock on wood that the stocker axle holds up.
    1980ish Free Spirit Sunbird fixed * 1996 Mongoose IBOC Zero-G * 1997 KHS Comp * 1990-ish Scapin * Lemond Buenos Aires Triple

  14. #14
    Senior Member
    Join Date
    Apr 2011
    Location
    Clarkston, MI
    My Bikes
    Mongoose, Trek 3700, Trek 7200
    Posts
    54
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    That would make sense, I was putting in $10 axles. They didn't give me an option of a more expensive axle, so I'm probably going to go with the cassette. This mountain bike is much easier to ride than my 30 year old mongoose with no suspension and a rock hard seat!

  15. #15
    Senior Member mrrabbit's Avatar
    Join Date
    Dec 2007
    Location
    San Jose, California
    My Bikes
    2001 Tommasini Sintesi w/ Campagnolo Daytona 10 Speed
    Posts
    3,180
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Low quality or high quality axles - dropout alignment should be checked. Period!

    =8-)
    4000+ wheels built since 1984...

    Disclaimer:

    1. I do not claim to be an expert in bicycle mechanics despite my experience.
    2. I like anyone will comment in other areas.
    3. I do not own the preexisting concepts of DISH and ERD.
    4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
    5. My all time favorite book is:

    Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life

  16. #16
    Quirky Grifter LesterOfPuppets's Avatar
    Join Date
    Sep 2008
    Location
    Vancouver, USA
    My Bikes
    My War
    Posts
    20,069
    Mentioned
    43 Post(s)
    Tagged
    7 Thread(s)
    Quote Originally Posted by mrrabbit View Post
    Low quality or high quality axles - dropout alignment should be checked. Period!
    +1.
    Same goes for freehub, get that alignment checked before dropping a new wheel in there.
    1980ish Free Spirit Sunbird fixed * 1996 Mongoose IBOC Zero-G * 1997 KHS Comp * 1990-ish Scapin * Lemond Buenos Aires Triple

  17. #17
    Senior Member
    Join Date
    May 2009
    Posts
    2,016
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I doubt they have any 7 speed freehubs in stock which will be compatible with your shifters. I am not sure whether they'll work when using only 7 sprockets of an 8-speed cassette, but I think they may. Sheldonbrown.com may be able to tell you if you can make a cassette work with your shifters.

    However, I would just try to get a chrome moly axle. A lot of axles for freewheel hubs are crap. I've seen poorer ones which are thinly plated and chrome moly ones which could put a dent in the poor ones, which were black oxided, but I don't know if that's always the case. Just ask for or order a chrome moly axle online.

    It's my theory that you also have to be very good about how you adjust the hub bearings with a freewheel-type hub if you want the axle to last.

  18. #18
    Constant tinkerer FastJake's Avatar
    Join Date
    May 2010
    Location
    Madison, Wisconsin
    Posts
    6,122
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by garage sale GT View Post
    I doubt they have any 7 speed freehubs in stock which will be compatible with your shifters. I am not sure whether they'll work when using only 7 sprockets of an 8-speed cassette, but I think they may.
    A 7 speed cassette will work no problem on an 8/9/10 speed Freehub with a spacer.

    IMO based on the OP's rate of axle breakage a chromoly axle is just a band aid of the real problem which is the freewheel design itself, once the dropout squareness is checked. Every wheel I've torn apart with a 7-speed freewheel has a bent axle, but these were wheels with solid axles from crappy x-mart bikes. In addition, my friend (130lb) recently broke the axle on his Giant Yukon with a 7S freewheel, and he does not ride hard. I've never seen a broken axle from a Freehub, although I'm sure it's possible.
    Why "derailer" is the correct way to spell the gear-change mechanism: sheldonbrown.com/derailer.html

  19. #19
    Senior Member
    Join Date
    May 2009
    Posts
    2,016
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by FastJake View Post
    A 7 speed cassette will work no problem on an 8/9/10 speed Freehub with a spacer.
    will the indexed shifter work? Are the sprockets the same distance apart? And what does all that stuff cost? Might be worth looking in to before choosing this route-an old 7 speed cassette might cost too much possibly.
    IMO based on the OP's rate of axle breakage a chromoly axle is just a band aid of the real problem which is the freewheel design itself, once the dropout squareness is checked. Every wheel I've torn apart with a 7-speed freewheel has a bent axle, but these were wheels with solid axles from crappy x-mart bikes. In addition, my friend (130lb) recently broke the axle on his Giant Yukon with a 7S freewheel, and he does not ride hard. I've never seen a broken axle from a Freehub, although I'm sure it's possible.
    I have had trouble with freewheels too. I looked into it a bit. Jobst Brandt, an avid cyclist and mechanical engineer, author of The Bicycle Wheel, said freewheel axle bending or breakage was a metal fatigue issue. In my eyes that makes it rational to simply put in a new axle and then check the wheel for wobble, replacing the axle every year or so or as needed, because it's going to be OK to use until it fatigues, just like an airliner.

  20. #20
    Constant tinkerer FastJake's Avatar
    Join Date
    May 2010
    Location
    Madison, Wisconsin
    Posts
    6,122
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by garage sale GT View Post
    will the indexed shifter work? Are the sprockets the same distance apart? And what does all that stuff cost? Might be worth looking in to before choosing this route-an old 7 speed cassette might cost too much possibly.
    Yes, yes, and not much. A 7-speed cassette will have the same spacing no matter what hub you throw it on. The spacer goes behind the cassette to take up the extra space provided to run an 8/9/10 speed cassette. Brand new 7 speed cassettes can be had for much less than $20 on ebay. The spacer should be a buck or two at most. The wheel would be the largest expense.

    Further reading: http://www.sheldonbrown.com/k7.html
    Last edited by FastJake; 04-18-11 at 04:49 PM.
    Why "derailer" is the correct way to spell the gear-change mechanism: sheldonbrown.com/derailer.html

  21. #21
    Guest
    Join Date
    Jul 2008
    Location
    Grid Reference, SK
    My Bikes
    I never learned to ride a bike. It is my deepest shame.
    Posts
    3,769
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I am heavier than the OP and, based on my experience road racing at 200 lbs, I would not trust a freewheel hub for serious riding - or any riding where I had to get myself home. Shimano's freehub design is one of the great improvements in bicycle component design from the last 50 years.

    The problems with simply replacing axle after axle as needed are that (1) much more time in the shop, (2) might not be good quality axles available the next time the axle bends and has to be replaced with another 3 mile cheapo, and (3) bending the axle might also bend the frame, and that's bad.

    Edit: One question for GeoffM - do you find you get a lot of pressure on your hands or wrists while riding?

  22. #22
    Godbotherer dwellman's Avatar
    Join Date
    Jan 2011
    Location
    Hermitage, TN
    My Bikes
    1986 Cannondale SR300 (full SRAM Apex) 1996 Cannondale R800 (Full SRAM Rival), 1997 Cannondale R200 (Shimano Tiagra), 2012 Cannondale CAAD 10-5, 1992 Bridgestone RB-1 (SRAM Force)
    Posts
    1,317
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Freewheels are evil. I can't replace them fast enough when they show up. I'm replacing one (crappy Joytech) right now (with FH-M430) , actually. . . getting an extra cog (7sp to 8sp), to boot.

    I otherwise won't ride a multispeed bike with a freewheel. Not worth the risk.
    "Do you not know that in a race all the runners run, but only one gets the prize? Run in such a way as to get the prize"
    "So I do not run like someone who doesn't run toward the finish line. I do not fight like a boxer who hits nothing but air."
    "And let us run with endurance the race God has set before us."
    "I have fought the good fight, I have finished the race, I have kept the faith."

  23. #23
    Senior Member
    Join Date
    Apr 2011
    Location
    Clarkston, MI
    My Bikes
    Mongoose, Trek 3700, Trek 7200
    Posts
    54
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by LarDasse74 View Post
    I am heavier than the OP and, based on my experience road racing at 200 lbs, I would not trust a freewheel hub for serious riding - or any riding where I had to get myself home. Shimano's freehub design is one of the great improvements in bicycle component design from the last 50 years.

    The problems with simply replacing axle after axle as needed are that (1) much more time in the shop, (2) might not be good quality axles available the next time the axle bends and has to be replaced with another 3 mile cheapo, and (3) bending the axle might also bend the frame, and that's bad.

    Edit: One question for GeoffM - do you find you get a lot of pressure on your hands or wrists while riding?

    You're 200, I'm 240. How are you heavier?

    My hands go numb. Usually at about 15 - 20 miles.

  24. #24
    Senior Member
    Join Date
    Feb 2009
    Posts
    3,974
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)

  25. #25
    Godbotherer dwellman's Avatar
    Join Date
    Jan 2011
    Location
    Hermitage, TN
    My Bikes
    1986 Cannondale SR300 (full SRAM Apex) 1996 Cannondale R800 (Full SRAM Rival), 1997 Cannondale R200 (Shimano Tiagra), 2012 Cannondale CAAD 10-5, 1992 Bridgestone RB-1 (SRAM Force)
    Posts
    1,317
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by davidad View Post
    Love the ASCII diagrams.
    "Do you not know that in a race all the runners run, but only one gets the prize? Run in such a way as to get the prize"
    "So I do not run like someone who doesn't run toward the finish line. I do not fight like a boxer who hits nothing but air."
    "And let us run with endurance the race God has set before us."
    "I have fought the good fight, I have finished the race, I have kept the faith."

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
  •