Crunching Gears on Font derailleur - please help / advise

Thebigbee

Hi - have been out most of the night without any trouble.

About an hour ago I went out to the 24 hr Tescos to get some supplies.

It is 2.3 miles there from mine.

I locked the bike up securely and backward ensuring I didn't touch and other bike.

Went in Tesco for 5 mins max.

Came out and attempted to ride away. The bike was making loads of noise. When I tried shifting into the big rind the sound was ridiculous and the chain kept slipping off.

Unfortunately during that 5 minutes inside I feel someone has come along and done something to my bike.

Just seems odd that I do 2.3 miles smooth as. Lock the bike up and try and ride away and the gears seem to be fkued.

I can't "see" any blatant damage but someone has done something.

Anyone got any simple clues or advice about what I could try?

Thanks very much

t.m.h.n.e.t

Check your derailleur cable adjustment

morstar

Have you got barrel adjusters on your front deraileur cable?
If the chain is going all the way across the big ring and coming off then the cable is pulling more than before.
You still shouldn't drop the chain as that is what the limit screws are there for.
However, if your front shifter is still working but just not indexed correctly then the cable tension has been adjusted. Could have just come loose.

Which side are you dropping the chain?

duckson

If its coming off the big ring (pedal side) the limit screw isnt set properly or is missing. If the cable is slack then by default the FD would be pulled in towards the smaller chainring.