Home Forums Bike Forum How would your tyre hit your crown?

  • This topic has 60 replies, 31 voices, and was last updated 15 years ago by mboy.
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  • How would your tyre hit your crown?
  • solamanda
    Free Member

    It’s not very hard to take a ruler to them so I wouldn’t risk it. A mate nearly spannered himself making that mistake when his tyre struck the crown bottoming out on a road gap.

    WorldClassAccident
    Free Member

    Okay, I have now measured them. Can someone check I have measured the right bits.

    The distance between the top of the tyre and the crwon is shown in green at 10.5cm.

    The distance between the top of the fork bottom bits and the crown where they meet is 11cm.

    I reckon this means that if I took all of the gubbins out of the forks the tyre would overlap with the crown by 0.5cm causing a load bang and projecting me in a graceful arc over the handlebars.

    I also reckon that it is unlikely that all the gubbins inside the fork will get squashed to less than 0.5cm so I am probably safe. Remember I will not be doing road gaps or riding Jedi’s wood work.

    Biffer – Forks are fine. I replaced the star fangled nut thing after about a month of riding without a bolt in it. People kept giving me strange looks when they saw me riding without the top cap or tensioning bolt.

    wwaswas
    Full Member

    if they’re 100mm travel you’ll be ok, probably.

    coffeeking
    Free Member

    If your forks could travel the full length of your stanchions then yes, you’d have a tyre impact but I’ll bet my bottom dollar the full length of the stanchions is not used. Fairly sure mine stop with about 10mm to spare, only way to find out for sure is to compress the fork fully, or measure from the top of you seal upwards by the number of mm travel your fork claims.

    WorldClassAccident
    Free Member

    I can’t get the forks within 1.5cm of the top regardless of how hard i jump up and down on them. I guess I am safe

    zokes
    Free Member

    More importantly, why on earth do you want that big wheel there in the first place?????? It’ll be wheely crap at climbing for starters, and pretty vague descending….

    WorldClassAccident
    Free Member

    South of England doesn’t have hills. It is rollytastic round Swinley. Lordwood and the New Forest. I don’t do climbs, I do walking if it gets steep and there is lock down on the forks if needed. Not sure what you mean about ‘vague’ on descents. It doesnlt seem to have slowed me.

    Olly
    Free Member

    tyre hits the crown?

    shoot that fork designer!

    let the springs loose,(or all the air out) and compress it all the way down.

    strikes me the top of the Lowers should hit the crown/stantion joint first surely?
    thats just sensible design?

    WorldClassAccident
    Free Member

    I can’t believe no one has commented about the state of my living room. The pot plants are too big and the fireplace needs cleaning.

    zokes
    Free Member

    Not sure what you mean about ‘vague’ on descents

    As in steering like a canal barge!

    Each to their own….

    MrNutt
    Free Member

    what’s the, erm, worst that could happen? 😛

    why not, y’know, just fix your puncture?

    WorldClassAccident
    Free Member

    MrNutt – there are lots of ways to get round the obstacles in life. just because it is obvious doesn;t make it right.

    MrNutt
    Free Member

    I can’t fault your logic! 🙂

    I_Ache
    Free Member

    You do realise that after all of this messing around on ‘tinternet and measuring things taking photos and messing around with them then uploading them and finally posting them just to get an answer has taken longer than it would take for me to drive from Birmingham realise the air from your forks and check if the tyre would hit then fix your puncture and drive back to Birmingham.

    Sorry for the lack of punctuation.

    WorldClassAccident
    Free Member

    But then what would we discuss on the forum 😉

    MrNutt
    Free Member

    you’re all beginning to sound over tyred,

    perhaps you need a lay down? 😆

    I_Ache
    Free Member

    Right thats me Im off for a ride on my totally un-niche 26″ wheeled 6″ FS bike.

    Have a fun night.

    avdave2
    Full Member

    Ones Crown might hit ones tyre if one was riding ones land when ones corgi runs under ones wheel causing one to go over ones handlebars. And no one wants to damage ones jewels.

    james-o
    Free Member

    “I guess I am safe” maybe not, something else to consider –

    the leverage on the crown area is increased when you fit 29″ wheels to 26″ forks – the radius is larger so the leverage is higher than the manufacturer may have factored in. Fox recently put out a notice warning about the danger of doing this, and although there is a saftey margin built into the design of all bike parts, you shouldn’t risk having the crown seperate from steerer or stanchions.

    Your risk, but i couldn’t ride that set up hard with confidence.

    james-o
    Free Member

    and it has the same effect on your headtube / down tube weld… it’s on a few-years-old alu frame too…

    mboy
    Free Member

    As I was the one that brought about the worry in the first place WCA, should probably chip in with the measurements you’ve given for everything, and the knowledge that your forks can’t get within 15mm of use of the full stanchion length showing, you *should* be fine even under full compression running this wheel. Though if the wheel deflects because of a hard hit (they do this you know!), it could be tyre into the brace time which would equal instant stoppage!

    *I do not take any lawful responsibility should anything bad happen!

    As others have said though, there’s lots of reasons not to do it. I can understand your thinking that where you’re riding, it should be fine for the most part as they’re not that hilly trails etc. Personally, I’d want some bloody mud room between my tyre and the fork brace. I’ve managed to stop a 2″ front tyre rotating inside a fork with loads of mud clearance, due to the ridiculously gloopy mud we get where I live. Not a problem now I’m running upside down forks at least!

    Oh, and I also don’t like running silly thin tyres, especially not on the front. If you’re riding Afan at the weekend, and haven’t done so before, I’d fix the puncture on your 26″ wheel and slap it back in personally! To me a 2″ tyre is narrow though, I like a bit of cushioning, and we’re all different.

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