Bike Forums - View Single Post - Need help with chainline/bottom bracket calculations

07-03-22, 09:46 AM

#3

Bill Kapaun

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Bikes: 87 RockHopper,2008 Specialized Globe. Both upgraded to 9 speeds. 2019 Giant Explore E+3

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Quote:

Originally Posted by alexk_il

I'm currently riding a 10yo Boardman hybrid bike with 10 speed 11-32 cassette. Will replace the cassette with Shimano M8000 11-42t 11speed cassette.

As this forum pointed out to me, the new cassette will fit my 10 speed hub because the lower gear has a recessed wide opening on the back:

https://www.bikeforums.net/bicycle-m...b-upgrade.html

The bike currently has 44mm chainline before the swap, I assume the center of the new cassette would be closer to the rim. Is this correct? If yes, by how much?

I'm replacing the bottom bracket too, might be able to compensate by getting the BB in a different size.

Let's face it. Unless you ride on only 1 cog per ring, your chain line is always going to be off on the other cogs. Sometimes way off.
Don't fret a couple mm.
I intentionally set my chain line a bit wide because I tend to use the outer cogs more.

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