Belt Conversion - Front Sprocket

This blog post is the 3rd of 4 Belt Conversion posts. Here are links to the two previous posts:

Rear Cog Removal
Rear Cog Install

Replacing the front sprocket was suppose to be the easy part.  A simple plan to remove the four chainring bolts, swap the sprockets, and reinstall the bolts.  Yes, a simple plan, indeed.  I suspect every train wreck in the history of train wrecks started with a simple plan to go from point A to point B.  Here's how my train wreck sprocket replacement went:

There's no need to remove the crank or even the pedal, as the sprocket will slide right over them.  The original chainring came off as expected ... then the derailing happened.  The tabs on the Gates sprocket didn't line up with the cutouts on the Middleburn spider ... they were too long ... it wouldn't install.  I bolted the original sprocket to the gates sprocket to show the difference.

You might have to click on the image to expand it enough to see how the Gates sprocket extends farther at each of the bolt locations.  It seems this crap should be standardized, but its obviously not.  Not sure if it was Middleburn or Gates that screwed the pooch, but I'm definitely the pooch in this analogy.

I had already filed on my expensive Rohloff hub, and I have to admit the pucker factor was pretty high.  Now, I have to either file the Middleburn spider or the Gates sprocket about 1/16th of an inch at each contact point.  I ended up filing both ... starting with the spider but found the sprocket was easier to grip and get good strokes with the file.  I hope I didn't bend the sprocket in the process.

Its done, but removing metal from components that are supposed to fit isn't fun.