CityCyclingEdinburgh Forum » Stuff

rail fail

(25 posts)

  1. unhurt
    Member

    Oops:

    Selle Italia Diva, year and a half old - lifting bike up one step into flat and it just snapped. It's sheared exactly behind the clamp, and when I went to take it off it was done up RATHER tightly - contributing cause?

    Anyway, now I need a new one. But do I get the same again - pretty comfy, same model as the one I used in Canada (that one has lost a lot of its "skin" and is now an emergency backup)? Never had a sadle rail fail, slightly worried it could happen when far away from replacements!

    Posted 7 years ago #

  2. crowriver
    Member

    Titanium rails? Maybe go for steel rails next time?

    EDIT - I see they're "Vanox" - Vanadium trioxide. Maybe brittle?
    Get a steel railed saddle next time, I doubt it will break.

    Also: lift bike by frame instead of saddle?

    Posted 7 years ago #

  3. unhurt
    Member

    Not titanium! And, well, I suppose that would be sensible, but it's a hard habit to break.... (The previous one of these I had survived a lot of woman-handling with a vast amount of gear on the bike, so not sure why this one has decided to fail!)

    ETA: Hmm, thanks @crowriver maybe steel rails are the way to go - but this one is so comfy...

    Posted 7 years ago #

  4. wingpig
    Member

    "Also: lift bike by frame instead of saddle?"

    When I expressed discomfort at storage solutions requiring hanging an entire bike by a single wheel, people pointed out that this would usually involve lower forces than involved when a person was sitting on the bike. This is sort of similar, in that a bike weighs less than its rider in most cases, but might be a similar force-in-a-direction-not-designed-for sort of issue.

    Posted 7 years ago #

  5. I were right about that saddle
    Member

    Vanox is just vanadium steel like they make spanners out of. When you blow the picture up (many pixels!) that looks to me like metal fatigue. Maybe one rail was flexing at the clamp, or maybe the seatpost clamp cradle doesn't quite match the rails of that saddle?

    Posted 7 years ago #

  6. unhurt
    Member

    Ahhhhhh that might be it - the clamp cradle was replaced when I put the new saddle on because the bolt was stripping; the previous clamp cradle was maybe an infinitesimally better fit?

    Posted 7 years ago #

  7. Arellcat
    Moderator

    maybe steel rails are the way to go - but this one is so comfy...

    'Vanox' (V2O3) is mostly likely the addition to the steel, not the entire material of the rails. Vanadium enables greater hardenability of steels, but can lead to embrittlement.

    Posted 7 years ago #

  8. Rosie
    Member

    I had a seat shear off when I was riding my bike. Fortunately I was on a cycle path, not going fast and I fell sideways into a hedge so was only bruised. I still think of that ragged cylinder of steel and shudder.

    Posted 7 years ago #

  9. crowriver
    Member

    "Vanadium enables greater hardenability of steels, but can lead to embrittlement."

    Also, vanadium steel spanners are generally rather thicker than saddle rails, and are not usually subject to regular pinching and flexing forces at concentrated points on the spanner shaft, unless misused.

    @unhurt, if I were you I'd just go for bog standard steel rails and maybe save a few bob on next saddle to boot?

    Posted 7 years ago #

  10. ivangrozni
    Member

    This article gives some answers: https://roadbikerider.com/tech-gear/tech-columns/diy/1241-preventing-and-fixing-broken-seat-rails-by-jim-langley

    Below a certain level, you should be able to cyclically load steel infinitely or so the "fatigue-limit philosophy" goes (it is a controversial topic - with some opposing views). You would think the saddle rail would be designed so fatigue should not be an issue - i.e. fatigue limit should be well outside expected loading. Maybe something was acting as a stress-raiser? localized dirt where it was being clamped? Or over-torqued? In the article above they also talk about cradle-sizes and designs (IWRATS barking up the right tree)

    Posted 7 years ago #

  11. crowriver
    Member

    Hm, so maybe worth investing in a new seat post too?

    Posted 7 years ago #

  12. unhurt
    Member

    @ivangrozni, cheers for the link - helpful! (And hmm: "riding technique and where you ride impacts rail longevity. Roadies who bounce their upper body with each pedal stroke stress the rails much more than smooth pedalers. Cycling over rough roads has a similar effect." - my italics. Hello sets, potholes, more sets - and a landrover track...)

    @crowriver Maybe a new seat clamp first - and I think it might be time to buy a torque wrench...

    Posted 7 years ago #

  13. I were right about that saddle
    Member

    Torque wrench and suspension seatpost?

    Posted 7 years ago #

  14. unhurt
    Member

    Actually... there's a suspension seatpost on my old Cannondale tourer (currently in bits in a friend's garage). Maybe it would fit?

    Posted 7 years ago #

  15. I were right about that saddle
    Member

    Maybe it would fit?

    Aha! Torque wrench and micrometer!

    Posted 7 years ago #

  16. unhurt
    Member

    This broken rail seems to be generating quite the shopping list! I might be in the market for borrowing a micrometer. Or swapping baking for a loan?

    Posted 7 years ago #

  17. Roibeard
    Member

    You're welcome to my micrometer (Vernier guage), and the torque wrench is a good call. Saddle bolts are done up surprisingly tightly...

    Daughter's saddle kept tilting until I broke out the torque wrench - I'd done it up hand tight, but no where near as tight as the spec!

    Robert

    Posted 7 years ago #

  18. Sheeptoucher
    Member

    I've got a torque wrench...

    Posted 7 years ago #

  19. unhurt
    Member

    @roibeard thanks! I will PM you. Struck down by germs at the minute so not sure if leaving house tomorrow but will see...

    @sheeptoucher You kept that quiet! Do I have to come fetch it?

    Posted 7 years ago #

  20. ARobComp
    Member

    Scotrail cancelled the 6:15 to Edinburgh from Queens street. Helpful lady commiserated that I'd missed the 6pm as it had been running 5 minutes late.

    Oh wait...

    Posted 7 years ago #

  21. ARobComp
    Member

    **rail wifi fail dual post**

    Posted 7 years ago #

  22. unhurt
    Member

    Thread de-rail? I would rail against this, but...

    Posted 7 years ago #

  23. ARobComp
    Member

    Sorry if I made you lose your train of thought.

    I'm reasonably chuffed I managed to get some puns in though.

    Posted 7 years ago #

  24. unhurt
    Member

    I'm always pleased to offer a platform for puns.

    Posted 7 years ago #

  25. I were right about that saddle
    Member

    Now drug-free cyclist Wiggo's had a rail fail.

    Posted 7 years ago #

  26. acsimpson
    Member

    The seatpost which came with my Boardman had a nasty habit of breaking the rail clamp bolt. It would creak most of the time but then the bolt would shear without warning. It happened twice before I bought a new seat post.

    Posted 7 years ago #

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