Cycling UK Forum

Did you perhaps catch the chain with your heel?

Isn't there a legal obligation in the UK to supply bikes 100% ready to ride? There wasn't here (France) until around 25 years ago. When I complained to a dealer about untightened screws in the 80s all I got was "well what did you expect?" More fool me.

Mind you, it'll be hard to prove you hadn't fiddled about with the mech.

The chain has unshipped repeatedly in THIRD gear.
Surely we are not saying that its the job of the front mech to keep the chain on the inner chainwheel IN THIRD? Then in first or second, the chain would be sawing away at the front mech?
I would be looking for a loose or bent chainring, or damaged teeth.

Jd843 wrote:I got a new bike online, and rode it for the first time the day after it was delivered. About 5 miles into the ride, riding uphill, already in 34x28, the chain dropped off the front. I hadn’t even changed gear at the front when it happened. I stopped pedalling straight away, but it was too late. The chain was completely jammed next to the frame, taking lots of paint with it. This happened twice more on the ride in exactly the same way. .........

Did the chain actually drop off the chainring, or did it fail to peel off the chainring at the bottom, and get carried round to jam between chainring and chainstay?

531colin wrote:The chain has unshipped repeatedly in THIRD gear.
Surely we are not saying that its the job of the front mech to keep the chain on the inner chainwheel IN THIRD? Then in first or second, the chain would be sawing away at the front mech?
I would be looking for a loose or bent chainring, or damaged teeth.

That was my thinking but has the owner used those bigger cogs yet?
Some photos would help, and confirmation of which bike he has bought.

peetee wrote:

531colin wrote:The chain has unshipped repeatedly in THIRD gear.
Surely we are not saying that its the job of the front mech to keep the chain on the inner chainwheel IN THIRD? Then in first or second, the chain would be sawing away at the front mech?
I would be looking for a loose or bent chainring, or damaged teeth.

That was my thinking but has the owner used those bigger cogs yet?
Some photos would help, and confirmation of which bike he has bought.

Yes I think the second time it came off I was in the 34 (sorry if my OP was misleading by saying it happened in the same way - by that I just meant I hadn’t changed gear at the front any of the times it happened). It’s a cannondale synapse.

With the bike in first gear and the shifter dropped through all the clicks (shift and trim) you should be able to see daylight between the chain and outer cage plate and that plate should be parallel to the outer chainring.

Jd843 wrote:

peetee wrote:

Jd843 wrote:
It’s my third largest (34, 30, 28) - does that make a difference to what the cause would be?

Not really. I was just trying to better understand the bike set up.
It’s not unusual for boxed bikes to need adjustments such as I have described. It’s also possible that it has had some rough treatment while boxed and the front mech has been rotated slightly. Was it running quietly before the problem?

It was running very quietly before that - I had no warning at all.

The front cage doesn’t look too far in at all. Could it be something else causing it?

yes, a not straight chainring or possibly even crank spider- it could be slightly bent/twisted or possibly a bolt is loose - i've seen this on brand new c/sets and it might run fine but get the perfect storm and it can throw the chain. A standard bike set up very often doesn't show this up, the drivetrain in a workstand is not under pressure. It is of course easy to rule this out, rotate the chainset whilst looking from above, you'll soon spot any wobble.

Update: was just looking at the chain and it looks like the connecting pin has been put in badly - it isn’t flush with the side of the link, in other words it hasn’t been pushed all the way through. I’ve included a couple of pictures of the inside/back of the chain link. The link feels loose and looks wonky. I can push the plates together with my fingers. Could this cause the chain to drop?

I'm staggered that you managed to ride that at all. Only one side plate is secured, under load you will get a wonky chain which will de-rail itself.
Its pretty poor workmanship, but it wouldn't necessarily show up when (if?) the selling dealer checked over the bike on the stand.

That looks like your problem and needs sorting before you ride the bike again. Don’t try to fix it, remove that link and replace it with a quick-link. Do be sure to check that it’s the only part of the chain that’s damaged.

That there be your problem!

That should not have been missed by QC after building but might have looked absolutely fine before it left the retailer.Luckily you haven't suffered a more serious issue

That chain has probably been separated from a long chain on a roll. The mechanic might well have used the wrong slot on the chain joining tool allowing the furthest plate to bend away as the pin makes contact. It also looks like a rough and ready ‘no-name’ chain, ie one of lesser quality - a common dodge used by manufacturers to reduce build costs. If you are looking for compensation from the retailer might I suggest that you get the chain replaced with the proceeds? It will almost certainly run sweeter for longer.

peetee wrote:It also looks like a rough and ready ‘no-name’ chain, ie one of lesser quality - a common dodge used by manufacturers to reduce build costs.

Tyres,chains and cassettes!
I've seen bikes labelled as "Ultegra" specced with cheaper chains and cassettes!

Navara wrote:

peetee wrote:It also looks like a rough and ready ‘no-name’ chain, ie one of lesser quality - a common dodge used by manufacturers to reduce build costs.

Tyres,chains and cassettes!
I've seen bikes labelled as "Ultegra" specced with cheaper chains and cassettes!

Indeed. What is a groupset these days? Time was when it included pedals, hubs, seat pin and headset.