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Old 07-23-18, 06:58 AM
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GraniteTandem
Tandem bicycle builder
 
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Join Date: Jul 2018
Location: Epping, NH, USA
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Originally Posted by kevrider View Post
was there any magic needed to make the road cranks play nice with the plus wheel and tire? boost cranks are the main reason i am reluctant to ride anything with plus tires.
There was some wizardry involved, but everything is in the spellbook to be cast again if needed.

The SRAM Force BB30 cranks had their spindle replaced with one about 10mm longer. This widens the Q-factor, but also sets them up for having a proper chainline with Boost hubs.
The maximum theoretical tire size for a 1X drivetrain, Boost (148mm thru axle) rear spacing, and adequate tire clearance is 3.0”. Any wider and there’s risk of the chain contacting the tire in the lowest gear.
To use road crankarms with this maximum tire size, the chainstays were heavily manipulated. For this bike, @Turbotandem knew exactly what chainring size they would use, so the chainstay length was set to clear those chainrings. For larger chainrings with 3.0” tires, we would need to lengthen the chainstays.
Finally, the Force crankarms are compatible with aftermarket spiders. We tested a Wolftooth Camo arrangement, but that came with a limited range of chainrings choices. For this tour, they used an NSB 104/64 spider with some minor tweaks.
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