Worn Chain Ring

[Andy3460]

Hi.

On my Decathlon Triban 500, the chain has started jumping badly when I pedal hard at slow speed in the middle chain ring. So say come up to a roundabout, nearly stop, gap in the traffic, set off and big noisy chain slip.

Done 1700 miles from new, original chain and chainring.

According to my chain measurer, and indeed a ruler, the chain isn't particularly worn, certainly not to the point that it urgently needs replacement.

See photo. Is it my eyes, or is the middle chain ring worn, and would this be enough to cause the jumping?

Never heard of a chainring wearing out faster than a chain.

I bought a new chain as they are cheap enough, and I wanted to change it before it wears out the cassette. Not fitted it yet, as don't want to damage it if the chain ring is worn.

Any advice gratefully received

I'm a trendy consumer. Just look at my HUAWEI VNS-L31 using hovercraft full of eels.

[Stradageek]

I'd defer to Brucey, if he's available for comment, but the ring doesn't look worn enough to be the cause of the problem.

I have encountered jumping due to a worn middle ring but only once the ring teeth were worn to little more than spikes.

If I had to guess I'd suspect a combination of cheap chain and cassette. I had a new tandem that suffered this problem, all due to a cheap chain.

If you've done 1700 miles you'll need to change chain and cassette together, the cassette will be way too worn to accommodate a new chain without pretty much the same jumping problem rearing it's ugly head.

Interested to hear how you get on

Toodlepip

Stradageek

[andrew_s]

It certainly doesn't look worn enough to slip.

Had you actually been riding in the middle ring before the slip? If you'd only just changed and hadn't pedaled since, the chain could have been resting on top of the​ teeth rather than meshing properly.

[Brucey]

I agree the middle ring doesn't look worn, but it could have a single damaged tooth or something (to cause a slip) or indeed there could be another reason/location for the slippage.

It might help if the OP can say exactly what happened (any shifting?), if the same thing happens regardless of which sprocket is in use at the rear, etc

For example if either of the two smallest sprockets is favoured, these ( I think because they are both small and manufactured differently from the others and may not be as hard-wearing) can wear hooked so that the chain will skip at the back, but only under load. This is easily mistaken for slippage at the chainring. The mechanism is that the chain fails to feed onto the sprocket smoothly as it leaves the rear mech, but only when under load. The chain will tend to ride over and skip one tooth at a time, each time making a loud 'clunk' sound.

cheers

[Andy3460]

Update...

Took the bike into Decathlon.
Bike guy checked Chain, Chain rings, cassette, gear set up.

Verdict. Chain not bad, but getting ready to change. Middle chainring worn. Everything else OK.

Crankset and chain replaced FOC.

Thanks for the replies.

I'm a trendy consumer. Just look at my HUAWEI VNS-L31 using hovercraft full of eels.

[Brucey]

So that sounds like a new chain on a used cassette...? have you tried it out yet??

cheers

[Andy3460]

So that sounds like a new chain on a used cassette...? have you tried it out yet??

cheers

Certainly have. Short ride with many attempts to recreate the problem. Behaved perfectly throughout.

Longer ride today. Any issues I'll report back.

I'm a trendy consumer. Just look at my HUAWEI VNS-L31 using hovercraft full of eels.

[ChrisOntLancs]

Longer ride today. Any issues I'll report back.

hiya andy sorry to dig up an oldish thread, feel free to disregard, but i've been trying to replace my b... my old bike... and with my limited funds the 500 is looking promising. you seem happy with the bike and you've got your moneys worth, what sort of rides do you do? how do the components hold up? i've got a boardman comp with a busted frame so a tiagra transplant is possibly possible.

i live in manchester and usually never do more than 40 mile trips, with 20-30 miles a day as my typical jaunt.

i lost my current bike at the cycling centre so decathlon was the first place i went, and after having a close inspection i must say i'm impressed for the price.

[/bluesharmonica]

[Andy3460]

Longer ride today. Any issues I'll report back.

hiya andy sorry to dig up an oldish thread, feel free to disregard, but i've been trying to replace my b... my old bike... and with my limited funds the 500 is looking promising. you seem happy with the bike and you've got your moneys worth, what sort of rides do you do? how do the components hold up? i've got a boardman comp with a busted frame so a tiagra transplant is possibly possible.

i live in manchester and usually never do more than 40 mile trips, with 20-30 miles a day as my typical jaunt.

i lost my current bike at the cycling centre so decathlon was the first place i went, and after having a close inspection i must say i'm impressed for the price.

[/bluesharmonica]

Hi. I'm well pleased with it overall.

I've done about 2000 miles on it since October, all on roads, and in the process gone from 125 kilos to 105, so it's had some use and some weight on it.

My typical rides are either a 13 mile each way commute, a 13 mile morning loop, or longer rides, usually 20 to 40 miles taking in hills. Did 100 kilometres a couple of weeks back. Longest ride of my life. I'm on Strava as Andy Charlton and I'm in Palmanova Mallorca if you want more details.

I have had a few issues. Back spoke snapped, they replaced the wheel. Front chainring worn and chain jumping, chain and crankset replaced. One pedal grinding. Pedals replaced with a better set. All under warranty and completely FOC.

So it's not been flawless, but on the other hand, it's fun to ride, it feels comfortable and has good handling, though as it's my first road bike for 30 years, I have nothing to compare it to.

At the end of the day, It's a 300 quid bike and it's probably had more hammer than it was built for, particularly with my weight on it. On my initial review on Decathlon, I concluded that if I had to replace it for the same money I wouldn't even look at a different model. Now, 9 months later, I still wouldn't.

I'm a trendy consumer. Just look at my HUAWEI VNS-L31 using hovercraft full of eels.

[gxaustin]

Seriously - change a cassette when the chain has only done 1,700 mls? Indeed change a cassette after only one chain? My chains last between 2,000 and 3,000 mls depending on the season and I've got sprockets that have done 10,000 miles and are fine. I ride all year btw.

[ChrisOntLancs]

At the end of the day, It's a 300 quid bike and it's probably had more hammer than it was built for, particularly with my weight on it. On my initial review on Decathlon, I concluded that if I had to replace it for the same money I wouldn't even look at a different model. Now, 9 months later, I still wouldn't.

MAN great post, i'm sorry i didn't wait to read it! managed to borrow a bit of money and get a 520.

congrats on the 100k! thanks again for the response!