Bmc rmo2 105

[Team carbon]

i recently purchased a new bmc when freewheeling a decent i have had the chain jump off and to the smaller cog for no real reason been back to Evans a couple of times but getting frustrating
They have been fast recents over 30 mph and maybe over a slight lump or something
Any ideas

 

[Cycleops]

You mean on the chain set?

 

[Team carbon]

You mean on the chain set?

Yes

 

[Cycleops]

It can only be the fd that's moving it, either a question of adjustment or maybe the cable is stretching.
Anyone else got any ideas?

 

[HarryTheDog]

chain a bit slack? one link too long, spring in the deraillleur a bit weak, or can be the freewheel is sticking a bit on the rear wheel which can lead to the top of the chain becoming very slack if you are not peadaling allowing it to jump off. Just my ideas for maybe caused by the top of the chain becoming slack. I take it that its jumping off when you are freewheeling?I have had it happen whilst pedalling normally because the front derailleur is not adjusted to go outwards far enough and is rubbing on the chain when on the smallest rear cog, but bike shop would have spotted that.

 

[Team carbon]

chain a bit slack? one link too long, spring in the deraillleur a bit weak, or can be the freewheel is sticking a bit on the rear wheel which can lead to the top of the chain becoming very slack if you are not peadaling allowing it to jump off. Just my ideas for maybe caused by the top of the chain becoming slack. I take it that its jumping off when you are freewheeling?I have had it happen whilst pedalling normally because the front derailleur is not adjusted to go outwards far enough and is rubbing on the chain when on the smallest rear cog, but bike shop would have spotted that.

It's been like it since new so not really sure it happens when freewheeling so I was thinking it could be loose

 

[Cycleops]

Are you used to doing your own maintenance? If so fit a new cable and readjust the fd for starters. Won't cost you much. Maybe @mickle might have some ideas.

 

[mickle]

Stop pedalling backwards.....

 

[Team carbon]

Thanks for advice it's back with dealer