Bike Build Question
 

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[Closed] Bike Build Question

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I'm just building up a Banshee Paradox V3 and have a question about 2021 XT crank set up.

The bottom bracket shell measures 73mm with the ISCG ring installed (these are separate on Banshees incase you trash your guide). I guess I still need to fit 1 driveside spacer with a shimano bottom bracket?

I've just installed a Shimano MT800 bb with one spacer on the drive side.

I then fitted some Shimano FC-M8120 cranks which come with 2 X 3mm spacers to go between the crank arms and the bb as per Shimano's dealer manual.

Once its all tightened up the crank arms are slightly further out from the driveside chainstay.

Drive side gap between the crank arm and chainstay = 19mm (17mm to chainstay protector)
Non Drive side gap between the crank arm and chainstay = 14mm

Looking at these numbers I should be able to get the crank arms evenly spaced by removing the 2.5mm spacer from the drive side bottom bracket cup.

What does STW think?


 
Posted : 21/08/2020 4:34 pm
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Are the chainstays actually symmetrical?

What you really want to be aiming for is the best chainline (nominally the distance measured from the centre of the frame to the chainring) which for Boost should be ~49mm.

See here and below:


 
Posted : 21/08/2020 4:59 pm
Posts: 824
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Topic starter
 

Cool thanks.

I’m not sure if the chainstays are symmetrical so I’ve asked Banshee.


 
Posted : 21/08/2020 10:41 pm
Posts: 43345
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If you remove the driveside spacer then the stopper plate pin (the plastic bit between the two NDS crank bolts) won't engage in the crank axle, so that can't be correct.

(see page 21)


 
Posted : 21/08/2020 11:03 pm

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