UKH

I bought a new bike and it had its first outing this weekend doing a portion of King Alfred's Way. the route is fantastic, especially the bit between Winchester and Salisbury, up to the plains... I would highly recommend if you like a bit of MTB/ gravel.

Anyway, one time, when I down shifted the chain came off and went past the small chain and down to the bottom bracket/ frame (new bike, presumably the limit screw isn't quite right or the cable has stretched, NBD).  However, the clearance between the chainset and the frame is tiny, and the chain actually got wedged up between the two components, so tight that it was a real faff to release it, and in doing so has scuffed a lot of the paint off in that area/ caused a bit of damage.

my questions are;

Is it normal for the tolerance to be this tight?

Is the best solution for this a chain catcher type thing, or is there an offset spacer for the pedal/ chainring assembly to increase the clearance a bit (would probably misalign the rear derailleur)?

Should I be concerned with the deep scrapes/ paint removal from the frame- it is carbon.

I want to know what I'm talking about before going back to the manufacturer with the issue.  If it it just one of those things, so be it.

In reply to La benya:

Yes, it can be

chain catchers are worth it on carbon frames but the mech should be adjusted properly to stop the chain dropping, but it can still happen off road etc.

If its in the paint just put some epoxy or nail varnish over it, if its in the carbon you may be in trouble, take the chainset off and check closely for damage, you can get a repair if required

It is one of those things, if it came from a bike shop they should have set it up properly, if you bought it and set it up then the issue is with you as it should have been checked, sorry...

In reply to La benya:

One of those things - I'm sure it changed fine on a bike stand, but have a look at it and tweak the limit screw to move the cage away from the frame, which should stop it happening again.  That's not to say it won't and it's usually a PITA when it does.  A scratch here and there is nothing.  This clip puts these things into perspective a bit (it's a mountain bike frame, but you get the idea)

youtube.com/watch?v=w5eMMf11uhM&

In reply to La benya:

It's not normal for a chain to come off when riding with a one by system, chain catchers are definitely not required unless you have a enduro or DH bike , just sounds like the bike was not set up properly.  Limit screw properly not set correctly, or gears badly indexed.

In reply to daftdazza:

As the op talks of down shifting and the chain going past the small chain. Which I’m guessing means it went past the small chainring, so maybe it’s not a one by system.

In reply to webbo:

Correct. 2x shimano 105 on a gravel bike.

Thanks all. I'll speak with Ribble and see what they suggest. 

In reply to daftdazza:

Bit of a sweeping statement! I have run a chain keeper on my carbon frames before to stop the exact issue the OP has had as they can and do drop chains from time to time.

Something like this:

https://www.cyclingnews.com/features/cervelo-testteam-get-testing-in-belgiu...

In reply to La benya:

This happened occasionally on my son's bike and I could not adjust it away - if I set the limit screw the shifter didn't move far enough to always change. I resolved it in the end by removing the chainset and putting a small circle of MX foam on the BB axle before replacing the chainset. Looked a bit shonky but worked a treat!

In reply to La benya: This was happening to me a fair bit on my carbon Canyon road bike and after advice from my bike mechanic I got a chain catcher fitted and it works a treat and has not happened since. I believe modern compact chain sets can be quite susceptible to this even if the front derailleur is adjusted correctly.

In reply to Dark-Cloud:

For a simple chain keeper a neat blob of Sugru can either be stuck to the seat tube in the usual place or used to (almost) fill the constriction down towards the BB to prevent damage. Generally around the bike it makes good little bumpers. 

In reply to Dark-Cloud:

Fair play, just never seen many people using them at cx races etc, only had my chain come off once during a race in thick mud, but that's because I didn't have a second bike. But they are definitely not required in usual one by system as chains rarely come off, like we are talking once every 1000hrs riding for me personally.  Problem looks to be a road groupset on a gravel bike, would at least hope Ribble supplied the OP bike with clutch rear mech to prevent chain slap etc on carbon frame.

And problem for OP might well be lack of clutch rear mech.

In reply to daftdazza:

Clutch isn't normal on a gravel bike, Whereas a 105 group set is. Although enon the route there were a few decent where a mtb would have been preferable, I didn't take them at any kind of speed which would have been cause for concern.

Regardless, this issue happened when down shifting up a hill on tarmac rather than any of the downhill I did. The mechanism of how the chain dropped is less concerning that the damage it is causing and the lack of clearance. 

A 1x groupset is fine for cyclo or more off road specific set ups but for a gravel bike also used as a commuter a 2x is more appropriate.

Sounds like a chain catcher is the answer! I've sent some photos to ribble and assuming they aren't bothered by the damage I'll invest. Just seems odd that they wouldn't have thought to make the clearance enough to not get the chain stuck! We're talking 2mm here and we would be fine. 

In reply to daftdazza:

OP drivetrain isn’t a 1x system, it’s a 105 double, totally normal on CX and Gravel bikes.