Wrong chainring?

[Chief Broom]

Hi folks. i would appreciate some advice here- Ive just fitted a new chainring to my Dawes Discovery 201 1 x 8 speed and the chain falls off the chainring in 1st gear whilst pedaling forward. Changes from 1 to 8 perfectly but wont stay on the first gear. The bike in pics is upside down and the chain can be seen to be starting to fall off. I sent Tredz all the right info but have they sent the wrong one? i noticed the old chainrings teeth are plain whereas the new ones teeth have chamfers which maybe suggests its for a groupset? The chain is relatively new with maybe 800 miles on it.

 

[raleighnut]

Worn Chain ?

 

[Chief Broom]

Worn Chain ?

Its fairly new and cant imagine thats the problem, i do have a new chain i could put on but dont want to faff with that if ive been sent the wrong chainring.

 

[HLaB]

Its fairly new and cant imagine thats the problem, i do have a new chain i could put on but dont want to faff with that if ive been sent the wrong chainring.

I've had a brand new KMC chain warp it link in under 100 miles and I don't put much power out.

Edit your picture looks like a stiff ling to me. the deraileur should be pulling the chain straight but you've got one link inner that seems to be pointing away from the chain ring.

 

[raleighnut]

Its fairly new and cant imagine thats the problem, i do have a new chain i could put on but dont want to faff with that if ive been sent the wrong chainring.

It is possible the 'offset' is out, test this by selecting the middle cog at the back which should be a straight line. other culprits could be a dodgy pulley wheel or too long a chain but that shouldn't be a problem in the lower gear

 

[Chief Broom]

Thanks for that HLaB but have i been sent the correct chainring? thats what i would like to know!

 

[Alex321]

Thanks for that HLaB but have i been sent the correct chainring? thats what i would like to know!

Almost certainly you have been sent the correct one, assuming it has the number of teeth you specified.

The only time the chain will slip or come off is if the chainring is badly worn, or if there is an issue with the chain - which does appear to be the case here.

 

[Ming the Merciless]

Is there one or more stiff links in the chain where it is coming off?

 

[Chief Broom]

Almost certainly you have been sent the correct one, assuming it has the number of teeth you specified.

The only time the chain will slip or come off is if the chainring is badly worn, or if there is an issue with the chain - which does appear to be the case here.

Thanks Alex321 as mentioned the chain is fairly new/ well maintained and didnt cause any problems with the old chainring.

 

[Chief Broom]

Is there one or more stiff links in the chain where it is coming off?

I'll go and check right now, but i dont reckon thats the problem- will check anyway.
Nope...just checked no stiff links.

 

[Ming the Merciless]

Plus does this occur when bike is the right way up?

 

[HLaB]

Thanks for that HLaB but have i been sent the correct chainring? thats what i would like to know!

The chainring will be fine but likely its like my edit you probably missed a stiff link in your chain :-)

 

[Chief Broom]

Plus does this occur when bike is the right way up?

er...cant see what diference that would make ive never had a chain fall of because the bikes inverted!

 

[Ming the Merciless]

er...cant see what diference that would make ive never had a chain fall of because the bikes inverted!

I’ll leave it to you to work out why, it’ll be more satisfying when you work it out. But the question remains, do you get the same problem when bike is the right way up?

 

[Chief Broom]

I’ll leave it to you to work out why, it’ll be more satisfying when you work it out. But the question remains, do you get the same problem when bike is the right way up?

I just turned the bike over and lifted it while pedaling and the chain came off. Im guessing that if there was a stiff link the tension would straighten it - will try riding it [when it stops raining]