SRAM Omnium snapped....for the 2nd time!

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  • I've snapped some Omniums on the drive side in the same spot. I'd put it down to oxidisation as the other side the peddle was stuck, they'd done about 18k miles on my winter bike.

  • They did and do make steel cranks.

    Either spend a lot of time trawling bicycle jumble sales and find some old road cranks (you may also need to find a cottered bottom bracket) or see if you can fit some BMX cranks to your bike.

  • They are designed to have a lot of power put through them by people with massive thighs riding on top of wooden boards.

    You are either cranking out too many watts, banged them on something, or got a lemon.

  • with steel you usually need to use welds and get a different set of problems.

  • If alu works for all the track sprinters in the world I think they're fine for the rest of us.

  • Yeah steel bmx cranks can still rust, and do still snap.

  • Are there any clues on the other side of the broken bit (the small part that would have been on the other side of the pedal)? Are they clean breaks without any dirt/oxidation?

  • I'm not really sure. Here is a picture of the other side.

    1 Attachment

    • IMG_20210916_160440.jpg
  • Thanks for posting. I'm not sure either now. Clean break areas and dirty areas don't match up, but as you say it did get dirt on from the fall.
    I have these and don't fancy a sudden failure, and I've also actually seen someone riding in front of me have the exact same break.

  • Reminder that velodromes have no rain, road salt, curbs to bunny hop off and sweet skids are frowned upon. And SRAM are fucking shit.

  • Difficult to see without cleaning it up properly and having it in front of me but it certainly looks like a progressive failure in which the dark surface has been exposed to the atmosphere for some time. The final clean bit on the dirty side has some ratchet marks which would have formed when large loads pushed the cracks through the remaining material each time you pushed hard on the pedals.
    The whole thing looks like it originated at the point where the pedal contacts the crank arm. As the pedal bites in to the alloy it will harden the material a little, making it more prone to cracking.
    I've just been out to check on mine and noticed that they do have black steel washers on, which would almost certainly prevent this type of failure.

  • velodromes have no rain, curbs to bunny hop off (potholes to hit at speed)

    Except Herne Hill.

  • Where are half the threads!
    The pedal ‘nut’ looks too big for the cranks, looks like there is some deformation at the edge of the nut where it contacts the cranks?

    Definitely looks like a pedal washer would be a wise idea, I’ve got quite a few on sram cranks and have used them occasionally where the pedal nut is too big for the recessed hole.

  • Looking at the original picture, the area that the pedals contact the cranks look pretty chewed up.

  • I'm just gonna go put those pedal washers on my Quarq powermeter after all... 😬

  • Pedal washers all day everyday

  • Yeah. Pretty sure all SRAM cranksets need to have the pedal washer installed.

  • Mine came with the washers in the box so I would agree

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SRAM Omnium snapped....for the 2nd time!

Posted by Avatar for tooth78 @tooth78