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  1. #1
    mtbr member
    Reputation: KingP's Avatar
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    Oct 2005
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    Chainline ASR-sl 2006

    Can someone tell me how to determine chainline position ?

    I am installing a Race Face Deus X-type crankset on my bike. And in RaceFace instruction after determining BB requirements (in this case 73MM for the ASR-sl) and installing the appropriate spacers (1 spacer on drive side fot the ASR-sl) you have to determine Chainline Position Requirements. They state the number of spacers required for 48,49 and 50MM chainline.

    Question is where and how is it determined if you 48,49 or 50MM?
    Anybody has a RF Deus X-type installed on their ASR-sl who can have a peek and let me know ??

    Thanks in advance !!

  2. #2
    Bomber
    Reputation: audi0phile's Avatar
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    Jul 2006
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    shoot for the gap, while building my 575 (first total bike build, but i had a mechanic by my side) I encountered the same problem with my evolves, he said its probably a 49, not to many bikes are 48, and a 50 is more for bigger bottom bracket shell (if i remeber right)...hopefully that helps, you can always contact yeti as well

  3. #3
    mtbr platinum member
    Reputation: bikerx40's Avatar
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    To measure your chainline, flip your bike over and measure from the center of your downtube to the center of the teeth of your middle ring. If you shift into the middle chainring and your middle gear in the back, your chain should look parallel to the centerline of your bike (straight ahead). If the chain is angled one way or the other, then you may want to add or remove spacers to your BB to get it straight. A straight chainline will give you the best overall shifting.
    I stopped driving my bike into my garage - I'm now protected with Roof Rack Ranger app for my iPhone.

  4. #4
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    Raceface Deus XC + Yeti ASR-SLC

    Here you go. In absurd amount of detail:

    Bottom bracket/Crankset installation

    Yeti's build kit came with Raceface Deus XC crankset. The Raceface instructions tell you to put a single 2.5mm spacer on the right side of the BB (for 73mm BB shell). If you then follow instructions for a 49mm chainline (1mm spacer each side), the cranks come out offset to the right. I measured 100.0mm right side (outside of crank at pedal attachment point to far side of seat tube) and 97.2mm left side. To get the pedals equally spaced on each side of the frame, I had to move the 2.5mm BB spacer from the right to the left, and move the left 1mm chainline spacer to the right (i.e. no chainline spacers on left side, two 1mm spacers on right side). This put the pedal spacing pretty much dead on. With this arrangement, the chainline comes out around 48.5mm (as near as I can measure it -- hard to do this accurately with Yeti frame).

    Also: I emailed Yeti tech support to ask for guidance on this issue. Their (Craig Grant's) suggestion was to put the 2.5mm BB spacer on the left (as I did above), and to put a 1mm chainline spacer on each side. I tried this, but found that this arrangement put my left pedal further away from the frame than the right. I didn't measure the chainline in this configuration, but if my measurement above is accurate, then it would have been 47.5mm.

    Note that (because the crank-crank distance is fixed), you can't choose an arbitrary chainline, and have the pedals symmetric. Similarly, if you want symmetric pedals, you can't choose the chainline. I guess it just depends what you think is more important.

    One final tip: The Raceface ISIS axle can be very tight, so that when you are tightening the crank bolt, it is not easy to know when you've bottomed out the splines. Apart from using lots of grease (as per instructions), my recommendation would be to assemble and then remove the crank (just unscrew the 8mm bolt), and repeat. After a couple of cycles, the cranks slide together with much less resistance, and it is very obvious when you've reached the end of the splines.

    Hope that helps someone!

    -- Dom

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