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  1. #1
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    Sinz cranks and BB

    So I'm getting ready to order the Cranks and BB for my son's build.

    I was wondering what other thoughts are on the size for the BB.

    I know it's either 113 or 108. Since I'm using a extra small 26 inch frame and the crank is a single chain ring, would I be better off with a 108 for the chain line?
    13 Lenz Lunchbox punkass

  2. #2
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    The sinz calls out for a 113 bottom bracket. I have seen people run the 108 on BMX bikes but they could not go with a big front chainring because it would hit the frame. See the link for the J&R Helpful hint on bottom bracket sizes https://www.jrbicycles.com/storefron...&productId=543

  3. #3
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    I wouldn't sweat it too much if you are running a 1x on a 26" frame for your kid. Lot longer chain stays than the BMX frame they were intended for. You could always swap which side you run the ring on, inboard/outboard, to gain a few mm back.

    I'm waiting on a 34T ring to install a sinz crankset on a 20".

  4. #4
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    Quote Originally Posted by TwoTone View Post
    So I'm getting ready to order the Cranks and BB for my son's build.

    I was wondering what other thoughts are on the size for the BB.

    I know it's either 113 or 108. Since I'm using a extra small 26 inch frame and the crank is a single chain ring, would I be better off with a 108 for the chain line?
    There's no way to know for sure without doing some measuring and a little bit of trial and error. It will depend on the frame that you are using and what crank seating depth the frame was designed for. For instance, Redline cranks have a deeper seating depth than Sinz cranks. Since I have a lot of spare parts from my son's BMX race bike (as he grows), it was easy to test fit different components to understand fit. I still ordered the wrong part. Oh well, I'm making it work. Good luck.

  5. #5
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    I'm running Sinz Cranks on my son's GF Precaliber with a 34 tooth chainring. I have it on a 113mm bb. Works mint.
    I like turtles

  6. #6
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    Quote Originally Posted by NYrr496 View Post
    I'm running Sinz Cranks on my son's GF Precaliber with a 34 tooth chainring. I have it on a 113mm bb. Works mint.
    I'm running a 113mm w/ sinz cranks as well. The 108mm would have moved the chain line 2.5mm inward or about 1/2 gear spacing inward. I still have plenty of front chain ring to chain stay clearance. My current chain line is exactly in line with the 4th smallest gear on my son's 1x8. The 108mm would have been slightly better for the Marin Hidden Canyon. Guess I'm splitting hairs.

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