Chain keeps coming off – what’s the most likely problem?

[TwoWheelsDC]

@jrenaut 151097 wrote:

My chain keeps popping off when I shift up into the big ring up front. What’s the most likely cause or causes? There’s a good chance I need a new crankset and a good chance I need a new chain but I was hoping to approach this a little more scientifically than going to the Bike Rack and asking them what’s wrong. So I’m asking you all.

Seems like maybe your upper limit adjustment is off. On your FD, the screw on the top that is away from the bike is usually the upper limit adjuster. Turning the screw should adjust how far your FD pushes the chain over when you shift. If the screw isn’t adjusted properly, it could be causing your FD to overshift and push the chain off the big ring.

[jrenaut]

I like fixes that involve screwdrivers and not new components.

[Judd]

Did it work? Or do we need to bring back Bike Forum Stump the Chumps?

[jrenaut]

I haven’t tried it yet. Maybe tomorrow.

[TwoWheelsDC]

@jrenaut 151099 wrote:

I like fixes that involve screwdrivers and not new components.

I like fixes that involve screwdrivers, but I LOVE fixes that involve new components.

[hozn]

I am sure there are a million YouTube videos, but I just shift into the big ring + small cog and then dial in the FD (turning the outer limits screw in) until the FD almost-but-not-quite touches the chain. Same procedure for the small ring + big cog and the inner limit screw, though you didn’t indicate a problem there.

[jrenaut]

We’ll see how that goes. Not sure I’ll make it out for a ride before tonight’s festivities, but we’ve got a long riding competition ahead of us.

[jrenaut]

Also, looking at the Park Tool repair manual, I think my FD was a little mis-aligned, so I straightened it out. Hopefully that will take care of the problem.

[Author]

Posts