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BB spacing advise

suntiger19651suntiger19651 Posts: 2
edited August 2013 in MTB workshop & tech
im building a carbon asr5 and using xt bb and the latest xt2x10 crank.
the question I have is the bottom bracket... if I install the 1 x spacer to the crank size as per the instructions and fit the crank it looks like the large front sprockett is inline with 5/6 gear and the smaller sprocket inline with 8/9

surely with a purpose made crank 2 x10, the gears shouldn't be in the position of the original 3 gear centre and small sprocket but spaced over slightly so more rear gears can be used on any on the front cogs?

anyone else noticed this and any advise will be helpful

thanks dom

Posts

  • nicklousenicklouse Posts: 50,675 Lives Here
    im building a carbon asr5 and using xt bb and the latest xt2x10 crank.
    the question I have is the bottom bracket... if I install the 1 x spacer to the crank size as per the instructions and fit the crank it looks like the large front sprockett is inline with 5/6 gear and the smaller sprocket inline with 8/9

    surely with a purpose made crank 2 x10, the gears shouldn't be in the position of the original 3 gear centre and small sprocket but spaced over slightly so more rear gears can be used on any on the front cogs?

    anyone else noticed this and any advise will be helpful

    thanks dom
    and the BB width is?

    and the big cogs start at one and the small cog is the total you have.

    on the front the big ring is on the outside


    so please have another look at what you have and correct the above info.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • The RookieThe Rookie Posts: 27,803
    Sounds like you can't line up by eye, if the chainrings were that far apart (3 sprocket/gap width hole take one rear sprocket out and the chain would fall in the gap) the chain would fall down the gap in the middle!

    Assuming your running 2x10, the gap between the front rings is near enough the same as between 2 rear spockets (set by chain width), so the gap between them should be centred on halfway between 5th and 6th sprocket (6 smaller than 5) and the larger chainring inline with 6 and the smaller in line with 5, however not all rear hubs put the cassette in the same place and the makers of the crankset don't know what you'll have, so it won't always be spot on.
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
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