So I got a problem with my gravel bike’s GRX Shimano electronic shifting. The bike is a year and 4 months old and doesn’t get ridden in the snowy months here in VT which is 5 months of the year.
I live in some of the best and hilliest gravel riding in Vermont. 12-15% grades are the norm for many hills. So I do need to go into my granny gear to climb with ease. But now when I go to my granny gear after about 10 seconds it shifts back to the next gear down. And when I do try to shift into the easiest gear, I hear this clicking for about 10 seconds before it shifts back down. What is going on? My husband is pretty smart and trying to figure it out. But maybe someone here knows how to rectify this?
OK I posted too soon. We fixed it. It’s the lower limit screw. Just needed one full turn. I knew it was just some kind of adjustment.
OK Carry on
The lower limit really shouldn’t move out of position from when it was initially set up so something else is almost certainly going on that you’d probably want to sort out.
Without looking at the bike it’s hard to accurately diagnose, but if it were my bike i’d check the following.
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There’s no dirt/grit on the end of the limit screw or the mech opposite the screw - kinda self explanatary, that would in effect lengthen the screw and require backing off to compensate, but runs the risk of that grit falling off and then leave the risk of overshifting.
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That the removable dropout screws are tight - can get loose and then that can cause the mech to ‘wobble’ and similar symptoms
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Least likely, that the mech bolt itself has come loose.
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Have you changed wheels/cassette? If so check any shims are in place behind the cassette. Less likely is that you’ve got the final (smallest) gear on incorrectly aligned with the small spline - in this case you can get the ring on and the lockring on but leaves the rest of the cassette with a little play.
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Worn chain. If it’s really worn then if can laterally bend more and that can lead to odd shift behaviour, but that’s only when it gets way past the point you should have changed it.
I say this as those limit screws are pretty well fixed and it’s not a ‘wear’ item.
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Oh wow! Thanks for all this. I’m going to share it with my husband. He’s very mechanically inclined and handy. And was a bike mechanic back in the 90s. But before electronic shifting.
We are experiencing a drought here in Vermont and the gravel roads are extra dusty. You should see my bike today. Luckily it was a flat ride on a rail trail as I’m recovering from two teeth extractions. But tomorrow I’m back on the gravel hilly roads and will need my baby gear.
Oddly enough, this happened a few months ago and my husband did a minor adjustment and it was fine for a while but did it again. So it could be something else. It’s been impossible to keep a clean bike lately.
PS no changes to wheels or anything