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  • 68/73mm BB Spacers, are they just to give chainline ?
  • weeksy
    Full Member

    On the Parkwood i can’t fit the 42T ring onto the outer of the spider as the chainline is horrible. It’s grindy, graunchy, etc. I can’t fit it on the inner as there’s no clearance.

    So, assuming i’ve got 2 drive side 2.5mm spacers, could i lob one over onto the non-drive side and then run it on the outer of the spider, giving me a better chainline ? I know it’s ‘unusual’ but would be nice for Zwifting to run the 42T for a few rides.

    Posted 4 years ago
    oldnpastit
    Full Member

    I alters the Q slightly I guess.

    It’s what I did on my FlareMax where I had a similar problem caused by trying to run a non-boost wheel.

    It hasn’t caught fire yet, but that might just be due to all the rain.

    Posted 4 years ago
    djflexure
    Full Member

    Yes

    Posted 4 years ago
    weeksy
    Full Member

    Cheers, experiment tonight after work then

    Posted 4 years ago
    convert
    Full Member

    I have an XT triple trekking on my winter bike and have two of the spacers on non drive side. Idea was the bike is mainly used in top two chainrings and it made chainline better for them (at the expense of small ring). Works for me though I do notice me left knee being further from the top tube than my right so the Q change must be a tiny bit noticeable.

    Posted 4 years ago
    richmtb
    Full Member

    Slight thread hi-jack

    On a 1 x 12 set up, where should the chain line up with the cassette?

    On my set up the chain is straight when its lined up with the smallest sprocket, all the other gears have the chain bent inwards, quite dramatically on the biggest sprockets.

    This seems wrong to me, should i space the chain ring inward so it lines up more with the middle of the cassette

    Posted 4 years ago
    walleater
    Full Member

    They allow the ability to use the same bottom bracket on either 68 or 73mm shells (which is probably stating the obvious). The ‘extra’ spacer is to allow the use of an E-type front derailleur. Which is why technically that spacer should be on the drive-side to get the ‘correct’ chain line. Of course in reality you can run that one on either side if you need to play around with chain line.

    Chain line on 1×12 is just fundamentally terrible but manages to work well due to sprocket design.
    That said, I think it was Wolftooth that had a good article that gave a run down on chain lines and using non-Boost rings on a Boost bike.

    Posted 4 years ago
    simondbarnes
    Full Member

    Would you not be worried about your feet not being centred?

    Posted 4 years ago
    djflexure
    Full Member

    By a couple of mm?

    Posted 4 years ago
    brownsauce
    Free Member

    should i space the chain ring inward so it lines up more with the middle of the cassette

    ideally , yes.

    Posted 4 years ago
    weeksy
    Full Member

    Fail anyway, removing means the crank hits the chainstay

    Posted 4 years ago
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