Cracked frame danger of single speeds- Mtbr.com
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  1. #1
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    Cracked frame danger of single speeds

    Hi anybody else cracked there frame from mashing on the pedals?
    Surprised it has happened would of thought a ss frame would be to
    The job!

  2. #2
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    not here. Brand, year? pics?

  3. #3
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    No, but I'm a normal BMI guy riding steel frames.

  4. #4
    The Crazy Cat Lady of VRC
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    It always makes me laugh when single speed guys tell me how much harder ss is on stems, bars, cranks, etc...and warm me to be careful with my lightweight set up....why would ss be any different from a guy who mashes hard all the time on his geared bike?

    Steve

  5. #5
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    My buddy just snapped the chainstay of his Superfly SS frame, but he's a monster !!
    Attached Thumbnails Attached Thumbnails Cracked frame danger of single speeds-bart.jpg  


  6. #6
    The Crazy Cat Lady of VRC
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    Quote Originally Posted by driver bob View Post
    My buddy just snapped the chainstay of his Superfly SS frame, but he's a monster !!
    sucks about the frame...but I seriously doubt it had anything to do with the "stress" of singlespeeding (especially since it's a two speed). Looks more like previous damage to the chainstay finally fatigued to the point of breaking. That or maybe dingles are more dangerous than singles


    Steve

  7. #7
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    Quote Originally Posted by eastcoaststeve View Post
    It always makes me laugh when single speed guys tell me how much harder ss is on stems, bars, cranks, etc...and warm me to be careful with my lightweight set up....why would ss be any different from a guy who mashes hard all the time on his geared bike?

    Steve
    As fun as it is to pretend we're super human, we're just not.

  8. #8
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    I have broken a frame at the BB from the strain for riding it but it was an old DH bike with a BB that was machined to be lighter and to stand up to the strain of riding the bike like a motorcycle than the repetitive strains of cranking its and my mass up a hill.

    I have not broken a frame single speeding even under my hefty frame, through rocks and drops in arizona including one frame that probably has 10 years of use as a single speed. Nor have I broken and stems, bars or steerer tubes from that stress. Chainrings and chainring bolts are a whole other question though. Broken plenty of them over the years single speeding.

    Stuff breaks, mountain biking is tough on bikes, single speed isn't any more tough than just mountain biking.
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  9. #9
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    Quote Originally Posted by eastcoaststeve View Post
    sucks about the frame...but I seriously doubt it had anything to do with the "stress" of singlespeeding (especially since it's a two speed). Looks more like previous damage to the chainstay finally fatigued to the point of breaking. That or maybe dingles are more dangerous than singles


    Steve
    Quite probable, he's raced it hard for 2+ seasons. This occasion he started to crank up a climb and *bang*.. wet noodle syndrome.

  10. #10
    Ovaries on the Outside
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    I'm super human, so I break frames a lot. But when I do, I weld them back together with my eye lazers.

  11. #11
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    Quote Originally Posted by eastcoaststeve View Post
    It always makes me laugh when single speed guys tell me how much harder ss is on stems, bars, cranks, etc...and warm me to be careful with my lightweight set up....why would ss be any different from a guy who mashes hard all the time on his geared bike?

    Steve
    Well in my case, I've noticed that the chain will normally skip or something will break on my geared bikes.

    Quote Originally Posted by SS Hack View Post
    As fun as it is to pretend we're super human, we're just not.
    True enough.

  12. #12
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    You have eye lazers too! Man, feels good to know I'm not alone.

  13. #13
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    Waiting to here from the builders it's about four years old if they don't
    Warranty the frame I will name the brand and put a pic up.
    It's had normal xc use once a week through the winter so it's
    Def not been abused. The tube has failed not the weld so not the
    Quality of the build that's a issue just quality of materials.

  14. #14
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    Quote Originally Posted by danza View Post
    Waiting to here from the builders it's about four years old if they don't
    Warranty the frame I will name the brand and put a pic up.
    It's had normal xc use once a week through the winter so it's
    Def not been abused. The tube has failed not the weld so not the
    Quality of the build that's a issue just quality of materials.
    Delete

    SPP
    Rigid.

  15. #15
    CB2
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    Quote Originally Posted by eastcoaststeve View Post
    It always makes me laugh when single speed guys tell me how much harder ss is on stems, bars, cranks, etc...and warm me to be careful with my lightweight set up....why would ss be any different from a guy who mashes hard all the time on his geared bike?

    Steve
    I don't know, most people I know who ride geared bikes make a point staying seated and spinning, whereas with the SS you have to stand, pull on the bars, and mash the pedals. I don't think SSers are going to be trashing well designed products but if there are any weaknesses they will easily be found.

  16. #16
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    +1 many SS riders ride rigid, which I can imagine to be harder on the stem and bar.
    Ride more!

  17. #17
    web-footed pedaler
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    Technically, being able to run a lower gear should put more stress on the frame, at least in the drive-train area, due to the mechanical advantage of the lower gearing. I would *guess* that we tend to put more stress on the bars and cranks from standing and mashing but I rarely hear of anyone snapping a crank arm or bottom bracket.

  18. #18
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    Quote Originally Posted by eastcoaststeve View Post
    It always makes me laugh when single speed guys tell me how much harder ss is on stems, bars, cranks, etc...and warm me to be careful with my lightweight set up....why would ss be any different from a guy who mashes hard all the time on his geared bike?

    Steve
    I've never broken a component on my geared bikes from simply torquing on it. On my single speed I've folded a cassette type cog and broken 2 chains.

    I think the difference is that on a SS bike you often come to a stop with full torque applied, just can't apply enough power to make the hill, can't push that pedal down.
    On a geared bike, that almost never happens - usually you run out of traction or can't keep the front wheel down or just plain run out of steam when you fail on a hill. Shear torque, being unable to force the pedal down rarely happens on a geared bike.

  19. #19
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    Quote Originally Posted by danza View Post
    Waiting to here from the builders it's about four years old if they don't
    Warranty the frame I will name the brand and put a pic up.
    It's had normal xc use once a week through the winter so it's
    Def not been abused. The tube has failed not the weld so not the
    Quality of the build that's a issue just quality of materials.
    Stay classy!

  20. #20
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    Quote Originally Posted by umarth View Post
    I'm super human, so I break frames a lot. But when I do, I weld them back together with my eye lazers.
    Jolly good points
    '11 Origin 8 700CX
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  21. #21
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    Quote Originally Posted by Slash5 View Post
    I've never broken a component on my geared bikes from simply torquing on it. On my single speed I've folded a cassette type cog and broken 2 chains.

    I think the difference is that on a SS bike you often come to a stop with full torque applied, just can't apply enough power to make the hill, can't push that pedal down.
    On a geared bike, that almost never happens - usually you run out of traction or can't keep the front wheel down or just plain run out of steam when you fail on a hill. Shear torque, being unable to force the pedal down rarely happens on a geared bike.
    on the other hand, single speeds don't suffer from chain suck, poor chainlines, dropped chains, and ham-handed shifting under load. i log tons of miles on big gear single speeds almost exclusively year after year and the only time i've ever broken chains is on geared bikes.

  22. #22
    Oaktown Honkey on Strava
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    Had a conversation with guy at NINER bikes.

    He was saying that my ONE 9 scandium (round tube style) was not engineered to be the strongest frame. Built to be lightwight, flexy, and reasonably strong. Great ride characteristics. I am good with that. I sold SIR 9 before I broke it. Yes, I disclosed it was put through the wringer. I also broke a carbon frame and will never get another frame other than steel or aluminum (but would if I were rich!). I always seem to find stronger riders than me. Umarth has lazer wit.

  23. #23
    Ahhh the pain....
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    Broke my Ti frame 2x in the past 3 years. It's been a SS since new.

  24. #24
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    Quote Originally Posted by Slash5 View Post
    I think the difference is that on a SS bike you often come to a stop with full torque applied, just can't apply enough power to make the hill, can't push that pedal down.
    On a geared bike, that almost never happens - usually you run out of traction or can't keep the front wheel down or just plain run out of steam when you fail on a hill. Shear torque, being unable to force the pedal down rarely happens on a geared bike.
    That's the scenario I think is the most stressing case for SS too.

    A little back of envelope calculation: assuming rider weight of 175 pounds, let's say the rider puts all of his weight on one pedal plus some added force resultant from bracing against the handlebars. We'll assume a fairly weak effort of 200 lbf on the pedal (rider adds an additional 25 lbf from bar bracing), and a fairly strong effort of 300 lbf on the pedal (rider manages to add 125 lbf from bar bracing). Nothing is moving so all this force translates directly into chain tension.

    Assuming 175mm (0.574 ft) cranks and an 80mm (0.26 ft) radius of chainring (I'm not sure what a good chainring radius is, I'm just guessing with no bike in front of me).

    200 lbf x 0.574 ft = 115 ft-lb moment about the bottom bracket, or
    300 lbf x 0.574 ft = 172 ft-lb moment about the bottom bracket

    This translates to:

    115 ft-lb / 0.26 ft = 442 lbf of tension in the chain, or
    172.2 ft-lb/0.26 ft = 662 lbf tension in the chain

    So nothing's moving and there's somewhere between 442 and 662 pounds of tension force in the chain. Keep in mind - if I overestimated the radius of the chainring, the calculated tension would go UP. Yea, I'd say that's stressful on the components.

    Imagine seting up your wheel in a stationary position. It's on a wall with the handlebars pointed towards the ground. A ~200-lb force is pushing it into the wall, holding it there. Now hang a 442 to 662-lb weight directly off the chain and see if anything breaks. It's almost exactly the same situation in terms of driveline stress. It's not what we'd choose to do in an experimental setup like this but it is exactly what we do every time we mash it up a hill.

  25. #25
    Ride da mOOn Moderator
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    Good job!

    Everything has a limit...

    ...frames, h-bars, stems, bottom brackets, cranks, chains...

    I'm not partial to SSers, I can break anything!

    And I don't blame anyone, but myself
    Attached Thumbnails Attached Thumbnails Cracked frame danger of single speeds-merli-5-20-12-028_900x900.jpg  

    Cracked frame danger of single speeds-merli-5-20-12-029_900x900.jpg  


  26. #26
    miwuksurfer
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    NEPMTBA, your bottom bracket probably broke because your chain is wrapped over your top tube and through your rear wheel!

  27. #27
    Ovaries on the Outside
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    Quote Originally Posted by miwuksurfer View Post
    NEPMTBA, your bottom bracket probably broke because your chain is wrapped over your top tube and through your rear wheel!
    Nah, it broke because it was embarrassed about the zip tie work on the fork.

  28. #28
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    I have broken a pedal spindal, handlebar, seatpost all just snapped while riding and my son cracked his frame. We were both riding rigid although he now has suspension. I am replacing my stem just to be safe and went with an all-mountain bar.

  29. #29
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    I have been riding a little over three years now. I have cracked three frames, all steel (1 monocog, 1 Jabber, 1 Elmariachi ). I will be celebrating if I can get more than a year of riding out of a frame. I have lost a bit of weight recently so hopefully that will help... But still, I wasn't that big (205)

  30. #30
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    As a frame builder...

    Single speed vs. gears is a small stress difference for frame.

    Big guy vs. small guy is a larger stress difference for frame

    Smooth trail vs. big crash in rocks is even larger stress difference.

    Driving the bike into the garage door while it is on top of your car is a huge difference in frame stress.

  31. #31
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    Quote Originally Posted by hallowedpoint View Post
    I have cracked three frames, all steel (1 monocog, 1 Jabber, 1 Elmariachi ).
    Regular Monocog or Flight?
    Ride more!

  32. #32
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    Quote Originally Posted by asphaltdude View Post
    Regular Monocog or Flight?
    Regular

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