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19mm MegaExo FSA Omega Modular Crank Not 73mm Friendly
#1
Preamble

A sad week for me, as I have been attempting to convert a 2017 GT Transeo 5.0 (in Gunmetal) into a road trainer bike for two years now. I've had so much trouble finding a rigid fork to cover the distance lost from the suspension fork (one that also includes disc mounts—and doesn't make the build look vulgar). I've gone through like 3 or 4 carbon forks, including an ENVE RD, all which were too short or the aforementioned (too vulgar looking). Finally settled on a Sunlite 700c rigid with post mounts. It looks like it might still be close, even at 165mm on the crank, but another recent break shows that the 30c/32c tires I'll now need (up from 25c—originally intended) may provide a little extra clearance for a 170mm crank even.

Addition

The Transeo 5.0 is a Hybrid bike, intended as an urban commuter, but oddly uses MTB standard schematics for the bottom bracket shell. Meaning, yes, it's a 73mm BSA shell. I originally tried a 53/39t FSA Energy, only for that spindle (not a 386EVO) to be too short for the shell. Then I wanted to a custom 50/39t Sora crank (to go with my 9 speed Sora groupset), but also the spindle was too short. It's very difficult to get road dynamics in MTB schematics. The BCD of these MTB cranks is typically 104 or now 96, and big brands Shimano/FSA/etc. don't make 50t chainrings and up with chainguards for these BCD. Being frustrated, I was finally willing to settle for an Octalink crank, down from a two-piece Hollowtech style crank (as originally desired).

Resolve

It was then I came across an FSA Omega Modular crank, whose modular capabilities would easily let me adapt a direct mount road ring to the crankset. This quickly turned into another nightmare, as I bought a Cannondale 5-bolt spider to pair the chainrings too, only for the spider piece to no be properly profiled to fit the FSA crank (despite them both using the same style direct mount); ultimately resulting in the threads getting sutured and me having to buy a tap to go over the lockring post with. Determined still, I decided to buy a 50T vision direct mount chainring, and reduce the build from a 2x down to a 1x setup. I installed the cups with no spacers and slapped the crank in there, which appeared to fit perfectly. There was visual clearance of the ends of the spindle to fit the modular side on. The man who sold me this crank was a bike mechanic who said that it should fit the 73mm shell given the length of the spindle. However, when I went to torque down the fixing bolts the crank began binding terribly. It would not spin freely, and even after removing the inner sleeve, was still binding hard when torqued down; so it clear to say that this crank is not compatible with 73mm shell despite the spindle clearance. And now I must start over yet again.
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