Spent 3 years installing chainrings backwards, a customer caught it

I've been doing shop work since 2019, mostly basic builds and tune ups, and I always put the chainring bolt heads on the drive side. Last month a guy brings in a vintage road bike for a crank swap and stares at my setup for a minute, then asks why the chainring is flipped. I looked at it, looked at the old one he brought, and sure enough the machined bevel and crank arm offset were on the opposite side. The whole time I'd been following some habit from my first shop where we used cheap single rings and it never mattered. Now I check the stamped part number orientation or the tooth profile direction on every install, and it's wild how many bikes I probably sent out with slightly off chainlines. Has anyone else had a basic step they just did wrong for years without ever noticing?

1 comments

1 Comment

the_sandra19d ago

Keep the bolt heads on the non-drive side actually. That way the chainrings sit flush against the crank spider and the load goes straight through the bolts. Drive side bolt heads can mess with your chainring offset on certain cranksets, especially the older ones. I only figured this out after a frame builder buddy pointed it out on a customer's bike.