New chain snagging on front chain ring

[Woodyboy]

Hi, I had my trek powerfly into Evans for a repair and they advised chain and cassette needed replacing. Stupidly I let them put a a slightly smaller (2 teeth I think) cassette on as that’s all they had.
When out riding on rough or uphill the chain is snagging on the front chain ring. The chain seems really slack also. I’ve removed a few links which has slightly helped but not resolved.
Any suggested appreciated.

 

[Mikerb]

what do you mean by "snagging"?
If the chain sounds rough on the chain ring, then the chain ring is worn and needs to be changed ( surprised the LBS did not advise changing chain, cassette and chainring at the same time).

 

[Woodyboy]

what do you mean by "snagging"?
If the chain sounds rough on the chain ring, then the chain ring is worn and needs to be changed ( surprised the LBS did not advise changing chain, cassette and chainring at the same time).

It’s folding under itself, as though there is too much slack chain and thrown at the chain ring. I’ll try and get a picture.

 

[Paul Mac]

It will be a worn chainring not meshing properly with the new chain

 

[Woodyboy]

It will be a worn chainring not meshing properly with the new chain

Cheers, I’m going to clean the derailleur etc tomorrow as I have rides though some rough mud and snow lately, maybe struggling to take the slack.
After that new chain ring

 

[steve_sordy]

It’s folding under itself, as though there is too much slack chain and thrown at the chain ring. I’ll try and get a picture.

That sounds like classic "chainsuck", where the lower strand of chain is carried up by the chainring instead of releasing and heading smoothly towards the mech. There are lots of articles to be read on chainsuck, but basically you need a new ring.

 

[Woodyboy]

That sounds like classic "chainsuck", where the lower strand of chain is carried up by the chainring instead of releasing and heading smoothly towards the mech. There are lots of articles to be read on chainsuck, but basically you need a new ring.

Thanks, I have been reading up and agree. Luckily only £7 replacement.

 

[Beekeeper]

It’s not the small Bosch front chain ring is it found on older cx motors? They wear incredibly quickly because of the small size

 

[Woodyboy]

It’s not the small Bosch front chain ring is it found on older cx motors? They wear incredibly quickly because of the small size

It’s a gen 2, only has 15 teeth

 

[Beekeeper]

It’s a gen 2, only has 15 teeth

yep same as mine. Simply reverse the ring (flip it over to the other side) you will get double the mileage out of it.

when I replaced my chain after 1000 miles I had terrible chain suck from the front ring. It dragged the new chain around itself which was very dangerous. Turning the ring over instantly solved the problem. I’ve now done over 2000 miles on the same chain ring. When I next need a new chain I’ll replace the front chain ring also.

 

[Kernow]

If the cassette was worn out the front ring would also be toast long before that .
A mate arrived last week I offered to fix his bike , he’d just been to halfrauds they had sold him a chain and cassette when all he needed was a chain . Gotta love robbing halfrauds

 

[Woodyboy]

I’ve removed the crank and locking elements to find the chainring is not flat, it has a lip on one side. I cannot find a replacement anywhere on the internet, has anyone previously located a trek Bosch gen 2 chainring 15t with a lip on one side please?

 

[Beekeeper]

I think you may need an “offset” 15t chainring

I had a look on Amazon but this one seems to be sold out....

Miranda 15t Bosch eBike chainring 3mm offset Black