Viewing 15 posts - 1 through 15 (of 15 total)
  • Rear wheel (lack of dish) correction… and paint touch up on steel frame?
  • vincienup
    Free Member

    Ok, so following from thinking that a 2.35 was a bit big in the back of my Soul (and before I do anything silly like buy new tyres…) I upended the bike and took a good look as it seemed the wheel was excessively close to the chainstay on the drive side. It is.

    Out of interest I test fitted a few other wheels – with and without tyres – and established by this method that definitely one and possibly two of my rear wheels are incorrectly dished/possibly not dished and the hub is therefore shoving the rim noticably to one side such that the tyre edge almost contacts the chainstay on one side and has loads of space on the other. Decidedly off-centre. As some wheels are ok, I’m assuming I don’t have a knackered frame. Hanger is also not bent/passes the straight-edge test.

    So, at some point very soon I’m going to have to look at these wheels, one of which (the one with the tyre tubelessed on… ) is a 20 spoke Mavic with the funny integral nipples.

    I gather that unless spoke length is fundamentally wrong, the issue has to be that the drive side should be higher tension and shorter spokes than the non drive and I should be able to tweak this with spoke tension? I’ve replaced odd spokes but never quite got around to popping my wheel cherry so a bit nervous about this – getting head round wheelbuilding is something I’ve been meaning to do for ages now.

    Also – while running the off-centre wheel, I’ve rubbed the chainstay to shiny metal in a tiny patch. Much less than fingertip. Frame is obviously steel – should I be touching it up or getting some converter or something on it? I’m not too precious about having a chip free bike (although I gather Revell 30 is a pretty good match) but it seems to me that bare metal on the inside of a chainstay is asking for it…

    RustyMac
    Full Member

    Whip the disk and cassette of the suspect wheel and put it in back to front and see if it is then too far over to the non drive side. If so the dish is out.

    vincienup
    Free Member

    Happy to try this, but other than a blind test, not sure what it gains me as I’ve already established that the suspect rim and tyre while running relative to the centreline are off to one side and that other wheels I have do not have the same issue? I’d be very surprised if I didn’t find the tyre touching the opposite chainstay given what’s already observed.

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    vincienup
    Free Member

    Hm, ok – now possibly confused.

    The suspected wheel is now without cassette and rotor.

    If I mount it ‘the right way round’ it’s damn close to the the chainstay and could easily rub – and clearly off centre.

    If I mount it ‘the wrong way round’ such that the freehub is on the brake side, I was expecting to see the wheel off to the side again – but the other side. What I’m actually seeing is a wheel/tyre running along the centreline… So, is this dish or is there possibly something odd going on with the axle? Is it even possible for a rear wheel axle to be offset to one side or the other?

    legend
    Free Member

    You keep mentioning chainstay but not the seat stay. I take it the wheel is closer to the seat stay as well? Otherwise I’d be wondering about how straight the frame is

    gilbertodepiento
    Free Member

    Yes that’s out if dish. If it’s now dead centre then it has moved it over. So the dish is out. If the back end were bent then the wheel would still be over to the drive side.
    Plus what legend says.

    vincienup
    Free Member

    I hadn’t considered seatstay as I only had rubbing on the chainstay and most of my bikes have had different clearances at each so didn’t even look.

    Just been back and the two wheels with tyre that are plainly off to the chainstay both seem reasonably ok at seatstay – but when reversed one of them is then off to the side a little but the other not – so while they’re both ‘wrong’ they’re ‘differently wrong’.

    My other ‘good’ wheel without tyre currently is nice and places the wheelbed nice and central to the centreline and therefore on chainstay and seatstay whichever way round it’s mounted.

    I’m currently leaning toward ‘two duff wheels’ as opposed to ‘knackered frame’ although I do have other frames I can try the wheels in later.

    vincienup
    Free Member

    So, assuming this is dish then which is what I think it’s looking like, is it as ‘simple’ to address as increasing spoke tension relative so that the non-drive side is pulled back to where it ought to be?

    Am I best detensioning everything before starting as the wheel seems to be reasonably tensioned already?

    And can I reasonably do this in the frame? I understand a truing stand would make life easier but as I’ve never gotten round to building wheels I never acquired one. Twanging spokes on one of the ‘suspected’ wheels (321 and pro2 – 36h) they seem to be at a generally lower tension than the ‘good’ wheel (also 321 and pro2 but 32h) – and the ‘good’ wheel seems to have a more pronounced higher pitch (so higher tension) on the drive side.

    takisawa2
    Full Member

    Slacken all the drive side spokes half a turn, then tighten the non drive side half a turn, till it’s running true & centred. Then add half a turn to each, plus another till your happy.
    Then grab handfuls of spokes & squeeze to de-stress. Then do some pinging & tweaking.
    This is all in the pdf book by Roger Musson.

    vincienup
    Free Member

    Ha. Cheers!

    I do actually have Musson’s book already (unread). Should have checked I suppose, subject blindness aided by web browser… Makes sense that a well regarded book covering building wheels might also cover what can go wrong with them!

    Is it reasonable to do all of this by ear and eye expecting reasonable results or would I do better to improvise a dish stick/acquire one first?

    Doh.

    RustyMac
    Full Member

    The dish of the wheel essentially just makes sure it is central between the end caps. You can do it by eye in the frame and while it may not be quite as accurate so long as it stops the frame rubbing then that is all you really need.

    I’d be trying to paint over the Un-painted area to help protect the frame.

    vincienup
    Free Member

    Cheers! I thought I’d want to cover it. I guess I’ll go with a couple of blobs of the sort of thing I used to use on bare metal on my olde Festers and the like (finegans no 1 or something…) and maybe a little colour on top.

    I get (forced) to learn wheels! This can only be a good thing…

    Thanks everyone!

    takisawa2
    Full Member

    Just put some heli tape over the bare metal area. Make sure it’s smoothed down well, & any bubbles are smoothed out. A hairdryer helps soften it. It won’t rust, & if it sees some action again from a badly mudded up tyre at least it’s not going to go straight down to metal again. My Niner has a right old rub mark. I put some tape over it & a year on the metal is still shiny under the tape.

    vincienup
    Free Member

    Shiny is good. 🙂

    globalti
    Free Member

    You can make yourself a simple dishing tool from a piece of batten with three long bolts or screws through the ends and the middle. Adjust the end bolts so that they touch the rim then adjust the middle bolt so that it touches the end of the axle. Then put it on the other side of the wheel and compare. The rim should be central on the axle.

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