(RS) Steerer tube replacement? Is it the done thing? How safe?

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  • (RS) Steerer tube replacement? Is it the done thing? How safe?
  • james
    Member

    Not my forks, but I'm considering buying them (for next to nothing). My brother was following me a bit close in the alps this summer and rode them into a seesaw while it was still up (not a very big one) but still a very sudden over the bars moment! The (handbuilt by merlin) front wheel remained perfectly true, the front tyre didn't pinch flat (folding tyre + XC tube), the fork still slides very smoothly, there doesn't appear to be any bending in the fork crown/stantions/lowers. Just that the steerer tube is bent, which forced the headset to ovalise the headtube in the bike

    Anyhow in the pic below, the steerer tube is NOT snapped, just bashed out (from above) with a hammer as the steerer is just a press fit (the crown hole doesn't appear to have any damage whatsover to it)

    I believe it was pretty commonplace to replace steerer tubes on some older marzocchi forks, but anyone any idea about newer (2008) RS (recon) forks?
    The steerer tube is a simple press fit, the top cap will make sure it all holds together, I assume the severity of the press fit would stop the fork being able to 'steer' on its own. I mean the 5-10Nm bolt clamping force on a stem works?
    Would it normally have some sort of glue/sliding locktight/etc/etc to help stop the steerer from rotating?

    Would you consider replacing the steerer tube? Would you ride it? Is it even available as a spare (that one is a steel one, an aluminium one would save weight so would consider).

    Or would it better to get new steerer/crown/stantions in one?

    bigyinn
    Member

    IIRC the steerer tube isn't replaceable on most modern forks, plus, where are you going to get a replacement steerer tube from? I'd be amazed if you were able to buy a new one.
    How on earth did he bend the steerer without totalling the frame?

    james
    Member

    The lower end of the headtube is ovalized to be fair (the bend in the head tube forces the headset cups to be at funny angles. The headset cup has been bashed forward again and the gap to the rear has been filled with liquid metal. ie a complete bodge. Under rider wieght the headset cup will be pushing against the intact front edge anyway
    A fair few areas around the headtube have got flaking paintwork as a result of it too though, presumably the frame was able to flex/stress more than the brittle paint?

    I'm not confident RS will do replacement steerer tubes, but theres an offchance I might be able to get one off another bent RS fork (steerer tube intact) from a friend

    Premier Icon speaker2animals
    Subscriber

    You obviously don't worry about things as much as I do. I'd be looking for a new frame and new fork.

    james
    Member

    I'm not riding the frame, my brother is, so I don't have to worry about that bit ..

    If I was to try to use the fork (with a new steerer tube) then I'd have something to worry about. Just trying to find some sort absolute reasoning not to
    Its not exactly impossible for the steerer tube to have been deliberatley designed to be the weakest 'link'?

    Premier Icon steveh
    Subscriber

    As said above you won't be able to buy one as RS don't sell them as parts. Your best option with those would be to split them for parts that other people need.

    cynic-al
    Member

    If you can get a steerer to swap, why not? If it goes in ok, I'd ride it.

    Premier Icon BigJohn
    Subscriber

    With your cavalier attitude to safety, you might find a bit of old broom handle lying around. They're all 1.125". If not, a bit of insulation tape will make it fit.

    james
    Member

    "With your cavalier attitude to safety"
    I'm not that bad, other forks have had replacable steerers in the past, and I can't find any damage to the rest of the fork at all? The steerer tube bashed out easily enough to push it from its press fit, a stem is merely clamped up with not loads of force and that works?

    I'm just wondering if theres any explicit warning/reason not to?

    Cynic-al, you're not quite living up to your name? ..

    Andituk
    Member

    Never understood why steerers aren't replacable anyway, surely they're just pressed in?

    cynic-al
    Member

    Am pragmatic when it comes to repairs, most doubters just don't understand how stuff works

    yes lots of steerers are/were pressed in. Iirc freezing is used these days

    Premier Icon brant
    Subscriber

    Would imagine the stresses endured by the crown, when the steerer did that, would be enough to cause problems in the future when things get a bit "big"… I'd not ride it.

    james
    Member

    It'd probably not be ridden over anything 'big' just going onto the XC bike, so no hucks/drops or anything really rocky. Probably some tabletops and some stairs though. Theres always a chance it could end up on the FS if/when the Revelation goes back to the menders again so couldn't really guarantee 'less than big' riding only

    LoCo
    Member

    New crown steerer time matey, the face plant when the crown snaps on a big landing is going to sting a touch. 😮

    Premier Icon speaker2animals
    Subscriber

    If it was a case of replacing a steerer because I'd cut it too short or if I was swapping too a bike that needed a different length I wouldn't worry. I'm just worried about this. I'd try to break for parts and get a new one but it's your call.

    Good to see your concern for your brother.

    Under rider wieght the headset cup will be pushing against the intact front edge anyway

    Roflcopter.

    That is all.

    thwang-01
    Member

    heat the crown up so it expands stick new steerer in the freezer to contract press fit job dont you need to use a bearing press

    JonEdwards
    Member

    AFAIK RS don't sell steerers alone, they only sell the complete crown/steerer/stanchion assembly.

    Slogo
    Member

    you cant buy these parts because its not safe to replace a steerer tube. there could be stress fractures around the top of the forks you cant see! there only recons so pick up a new set £160 ish.

    if you use them you will only waste more money repairing them and **** a new frame when they break again and you face plant in to the road/track/mud and need new teeth! then your go visit your brother in hospital after his head tube snaps!

    i bet your the kind of person who leaves the shed open or bike unlocked and wonders why its stolen!

    james
    Member

    "i bet your the kind of person who leaves the shed open or bike unlocked and wonders why its stolen! "
    Nope

    I hadn't really thought about it that much though, the crown potentially being a 'timebomb' waiting to snap. Hmm

    So new steerer/crown/stantions would be fine? (depsite being what, £100-150?)

    coffeeking
    Member

    This can only really be a troll when put in tandem with the errrr tandem thread!

    🙂

    Personally I'd want to know exactly how the fork was designed before pressing a new steerer in. Even if theres no crown damage visible you may have just shoved it nearer to its failure limit, not sure I'd like that but if I were broke I might risk it on a low-impact bike.

    james
    Member

    No no, I (was) thinking of how plausible/safe it would be to make the fork ridable again. The crown is probably not worth the risk

    I just had 2 thread ideas to put up, so while I was putting one up, I thought I'd put up the other is all

    If I was able to get the bent recon from a friend, I might be able to use the complete steerer/crown stantions assembly, though due to the way the fork is bent I think the stantions will no longer be parallel

    james
    Member

    Okay, so if the crown is/was damaged/stressed/strained beyond/near to its limits, would the more brittle paintwork show signs of this, eg flaking/stretching etc..
    I know theres an awful lot of assumptions in asking that, many of which I believe to be false, but I'm interested in the whys

    Zedsdead
    Member

    If you can get hold of a new steerer then yes you could fit it. I'd freeze the steerer then press it in.

    However I would check the rest of the fork very carefuly as clearly a lot of stress has been put through it. I've seen a lot worse repaired and used though…

    james
    Member

    The pic isn't overly clear, but the visual bend in the steerer tube is about 50-60mm up from the base of the steerer tube, ie not where the crown is, it looks as if its bent where the steerer tube jumps to a thinner thickness
    I realise the steerer tube could still have bent/slipped within the crown as well

    Zedsdead
    Member

    As for stressed metals – we use a special paint to show stress on various things we are working on in our business.

    james
    Member

    Hmm altough the thickness should be the same as for the crown race, so the RST steerer tube should fit, I can't help doubt the tolerances would be out (despite it suppoed to be exactly 30mm) to run an RST part in a Rockshox Fork

    retro83
    Member

    Hmm altough the thickness should be the same as for the crown race, so the RST steerer tube should fit, I can't help doubt the tolerances would be out (despite it suppoed to be exactly 30mm) to run an RST part in a Rockshox Fork

    i think that's the least of your worries! don't the oems use liquid nitrogen to install stanchions/steerers into the crown?

    Can't be bad for a £5er. Worth it for the sheer bodginess of it. Also, cut one of the legs off and fashion it into a lefty.

    james
    Member

    The old bashed out easily enough with some good whacks with a hammer, I'd assume it'd bash back in again as easily? Though steerer tube in the freezer beforehand and towel around the crown and pour boiling water on would help to get it in more smoothly?

    bommer
    Member

    I'd have thought if you smacked the old one out 'fairly easily' the crown hole is already fairly flared/damaged. Why not fit a new one, then drill a hole through the crown and steerer then stick a nut and bolt through the whole lot? It'll snap around the hole but you'll KNOW where it's gonna snap….

    retro83
    Member

    i'd be concerned that the crown was damaged if it popped out that easily, still worth trying the bodge if its only a £5er though

    Zedsdead
    Member

    When installing use a Loctite product to make sure it won't move.

    Premier Icon BigJohn
    Subscriber

    I don't know if James is a troll or Russ Pinder's neighbour but if you have an impact that breaks the fork, bends the frame and breaks the headset then scrap the lot and start again.

    tinsy
    Member

    James, yes the hot and cold thing is how it would have been fitted at the factory, its just an interference fit part, kinda like a headset cup but with more interference, if you was to take that to an engineering shop I have no doubt they could turn you a nice new steerer, and advise you on the interference fit your after (they will measure the steerer and Crown to work that out, now you might have lost a little of the interference by bashing the old steerer out but thay can make that up on the new steerer, if you are really concerned just crack test the crown too to be on the safe side. (you will have to lose the paint on it to do that though)

    It would be cheap enough to crack test and to make a new steerer, if you have any trouble I can get it done for you.

    You of course would have to assume responsibility if anything was to go wrong, but if it was me I would definitely explore repairing it.

    james
    Member

    "impact that breaks the fork, bends the frame and breaks the headset"
    The fork isn't actually broken, the steerer tube is 'only' bent at a stress riser* where the steerer tube changes from a much thicker thickness to a narrower thickness relatively suddenly

    Only the lower end of the headtube (the unsupported/ungussetted) where the headset sits was slightly ovalised. The headset cup has been refitted into the 'normal' position with some liquid metal filling the little gap behind the headset cup (which isn't as deep as the headset cup)

    The headset cup is fine

    *I think this is correct?

    "if you are really concerned just crack test the crown too to be on the safe side. (you will have to lose the paint on it to do that though"
    So if it had been near to breaking point then there should/ought to be signs of flakey paint/stressed paint?

    tinsy
    Member

    I dont know about that, its not like its going to cost a load more to find out, but if your confident there isnt a problem with it, its your call.. They can test it will aerosol crack testing stuff, would take about 10 mins with the paint removed from it.

    james
    Member

    How does a crack test work then? ie, will it break the crown (if its not already)? Like testing to (or near to) destruction?

    Hmm, At least if the outcome of a crack test was favourable enough to ride I could have a unique* silver RS fork crown?

    *I assume

    Premier Icon wwaswas
    Subscriber

    Also, cut one of the legs off and fashion it into a lefty.

    🙂

    my view: my looks (such as they are) and skull are worth more to me than the cost of a knackered set of donor forks with the steerer still attached and decent set of stanchions.

    You may get all this working (but as has been said – if the steerer was fairly easy to remove then suspect further damage elsewhere) but would you trust your life to it?

    coffeeking
    Member

    Worth a punt if I'm honest, if you can get a second steerer and press it out without damage. Local workshop will do the job for you for £20-30 I suspect. They could, as said above, also probably turn you a new steerer if they're any good, but that would be more pricey.

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