The limit screw is not going to move on its own. More likely to be the mech hanger has taken a knock so I suggest checking that before continuing to ride the bike.I had a similar experience the other day, it was the rear mech hitting the spokes when on the largest cog, I guess the low limit stop had moved slightly. Didn't get the noise on the flat or under low pedalling force, but as soon as I hit a hill 'ping-ping-ping' it went. A half turn on the low limit screw by the roadside fixed it.
Good point, I'll give it a check over the weekend. I did put a new mech on a few weeks ago and it's been ok until the last couple of rides so maybe something has just come loose (fingers crossed).The limit screw is not going to move on its own. More likely to be the mech hanger has taken a knock so I suggest checking that before continuing to ride the bike.
Checked the hanger bolt and found I could get about another half turn or so before it was fully tightened so hopefully this was the source of my problem, I'll find out tomorrow if the weather ever cheers up!Good point, I'll give it a check over the weekend. I did put a new mech on a few weeks ago and it's been ok until the last couple of rides so maybe something has just come loose (fingers crossed).