Ecavalino

Went for a 40km ride and on the way back when in top gear it kept slipping down to a lower gear..... There's no rubbing on the derailleur or forewarning.... Any advice as to what to do? I looked at it when I got back and can't figure it out. Also noticed that several teeth onnon all 3 chainrings seemed to be very earn ... Again advice?

JourneyLightly

Not clear exactly what's happening from your description. Is the chain slipping from bigger chainrings to smaller ones in front? Or is the chain moving from smaller cogs to bigger cogs in back?

Ecavalino

Cogs in he back

UmneyDurak

Probably just need to adjust the derailure.

BlastRadius

If the derailer adjustment, the derailer hanger could be bent.

VaultGuru

You are probably hearing a considerable amount of chain noise in your biggest gear. The reason is that your derailleur is set too far to the next lower gear. You have to do do one, or both of the following.
1. Loosen the outward derailleur limiting screw slightly so your chain can ride in alignment with the center of your chain in the top gear. May take between 1/4 and 1/2 turn on the screw.
2. Adjust the cable tension so your chain will ride in alignment with the center of your chain in the top gear. You have to turn the cable tension clockwise.
Check to see that the chain is riding in the middle of the gear and you can click your gear one time to make the chain move to the next lowest gear. Adjust accordingly.
3. Your cable could be too tight and not allow your derailleur to move outward a far as required. You may have to reposition the cable prior to doing #1
+1 on BlastRadius

Ecavalino

Thanks .... All better now and no slipping into the next gear.