What chainring? Newbie question.

[Steelyglint]

Hi all, I have Cube reaction hybrid race 750 2023 model that the nut which secures the chainring has come loose on. The bike has done about 600 miles but not sure how long it's been loose. I only spotted it as I was cleaning the bike more thoroughly than usual. The internal splines on the chainring now seem quite damaged, now pointy and sharp so I think a replacement would be a good idea. ( The motor shaft spline seems ok, must be harder) Does anyone know what oem part will fit? It's black, 38 teeth and has 5 equispaced bolt holes for the plastic chain guard. When I take the chain ring off it's one piece (no spider) and there is a separate spacer ring / washer that sits behind it but no o-ring. Its a Bosch cx gen 4 I believe.

 

[steve_sordy]

Welcome to the Forum.

Is this it?

Cube Acid Chainring Hybrid HPS CL50 BDU33 Chainring - Black

www.cyclesolutions.co.uk

PS: After only 600 miles, is the bike still under warranty? Take it back.

 

[Mister cube]

Hi all, I have Cube reaction hybrid race 750 2023 model that the nut which secures the chainring has come loose on. The bike has done about 600 miles but not sure how long it's been loose. I only spotted it as I was cleaning the bike more thoroughly than usual. The internal splines on the chainring now seem quite damaged, now pointy and sharp so I think a replacement would be a good idea. ( The motor shaft spline seems ok, must be harder) Does anyone know what oem part will fit? It's black, 38 teeth and has 5 equispaced bolt holes for the plastic chain guard. When I take the chain ring off it's one piece (no spider) and there is a separate spacer ring / washer that sits behind it but no o-ring. Its a Bosch cx gen 4 I believe.

 

[Mister cube]

This is what you need,but you need the tool to tighten it up,or take it to your LBS 2 minute job,you need to remove crank arm to put it on,which you also need a tool to undo crank arm bolt
ps its not a chainring you need,the metal shavings are probably from the alloy nut,the crank spline is steel,so possibly thread stripped,no biggy just get nut replaced

 

[steve_sordy]

This is what you need,but you need the tool to tighten it up,or take it to your LBS 2 minute job,you need to remove crank arm to put it on,which you also need a tool to undo crank arm bolt
ps its not a chainring you need,the metal shavings are probably from the alloy nut,the crank spline is steel,so possibly thread stripped,no biggy just get nut replaced

That sounds like the voice of experience!

 

[Mister cube]

That sounds like the voice of experience!

Afraid so steve

 

[Steelyglint]

Thanks for the replies. I answered my own question when I stripped the chain ring off and removed the damaged chain guard which was covering up the IDs. These are the internal splines looking a bit knackered. The OE chain ring is identified as SFCB45238 and branded KMC. It's 38 teeth with a chainline of 52 I believe. The plastic chain guard is badly damaged for no apparent reason which is bit of a head scratcher and I've replaced it with one off Amazon. I'm reusing this chainring until the replacement I've now ordered arrives in the post.

 

[Steelyglint]

The chain guard

 

[Mister cube]

Thanks for the replies. I answered my own question when I stripped the chain ring off and removed the damaged chain guard which was covering up the IDs. These are the internal splines looking a bit knackered. The OE chain ring is identified as SFCB45238 and branded KMC. It's 38 teeth with a chainline of 52 I believe. The plastic chain guard is badly damaged for no apparent reason which is bit of a head scratcher and I've replaced it with one off Amazon. I'm reusing this chainring until the replacement I've now ordered arrives in the post.

View attachment 158085 View attachment 158086 View attachment 158087 View attachment 158088 View attachment 158089

That chainring was never torqued up from new to have that wear.

 

[Steelyglint]

Thanks for the help. Should I be surprised there was no o ring? I guess it could have been lost between the time it came loose and the time I realised. Should I fit one, or are they superfluous? & What grease is considered appropriate?

 

[Mister cube]

Thanks for the help. Should I be surprised there was no o ring? I guess it could have been lost between the time it came loose and the time I realised. Should I fit one, or are they superfluous? & What grease is considered appropriate?

Some have o rings,some dont,dont fuss over it too much