Chain slipping?

[The Bear]

I've started suffering from chain slipping since recently putting a larger front chainring on my 11 speed 2018 Cube Reaction Race. It's only when i'm in 10th & 11th gear.

I went from the standard 12T chainring to a 15T to get a bit more top end speed, and fitted a new chain of the same size at the same time. It feels like its the front chainring thats slipping, but I can't be 100% certain.

What could be causing it?

 

[Andy-Mat]

I've started suffering from chain slipping since recently putting a larger front chainring on my 11 speed 2018 Cube Reaction Race. It's only when i'm in 10th & 11th gear.

I went from the standard 12T chainring to a 15T to get a bit more top end speed, and fitted a new chain of the same size at the same time. It feels like its the front chainring thats slipping, but I can't be 100% certain.

What could be causing it?

Put a marking across the connection, something like maybe white paint and see if there is any movement.
Replacing the chain ring and not cleaning the two mating surfaces, maybe old oil is allowing some slip, or not tightening up the fixings, is where I would look if the white mark shows movement.
(It sounds like I have done this before, totally untrue!)
Best wishes
Andy

 

[mike killay]

My guess is the rear cogs, particularly if you have an 11 tooth one

 

[jokskot]

12 and 15T on the chain ring?

 

[Deleted member 25121]

A problem with the chainline (chain angle) maybe?

 

[SwampRodent]

I also think it sounds like the rear cogs, I've had this a few times when I've replaced the chain but not the rear cogs (I know bad practice!), the higher gear / smaller cogs have very few teeth so it doesn't take much for them to slip, the chainwheel on the other hand has around 50 teeth and the chain is in contact with about half of the teeth so unlikely its the chainwheel slipping.

I have had the pawls in the freewheel slipping before now which feels kind of similar but this will happen in every gear.

Its possible fitting a larger chainwheel has altered the chain tension.

 

[The Bear]

... the chainwheel on the other hand has around 50 teeth and the chain is in contact with about half of the teeth so unlikely its the chainwheel slipping.

My larger chain wheel only has 15 teeth. But perhaps it is the rear cogs, with gear 10 & 11 having the smallest number of teeth I guess that’s possibly the cause.

At the rate I’ve been going through chains, (about every three months) if I changed the rear cassette every time at £50 a pop I don’t think I could afford to keep the bike on the road.

 

[The Bear]

12 and 15T on the chain ring?

Yes, the original was 12T but I’ve changed it to a 15T. But I may have to switch back to the 11 now.

 

[SwampRodent]

I have the same issue that I'm swapping chains out every 3 months / 1400 miles then swap the cassette and chainring after 3 chains otherwise like you say it gets ridiculously expensive.

I have a 48 tooth chain wheel up front and my smallest cog is 11 tooth, this gives me a realistic top speed of 35 mph, I have done 46 downhill pedalling like a loon and screeming like a girl! I would love a 52 tooth chainring but it will foul the frame.

Conversley I think my largest cog is 36 tooth as I have to have the ability to climb a 20% grade if the motor / battery fails.

 

[Nealh]

Check the chain links carefully for any damaged or kinked links, do they all individual swivel ok or may be a tight link.

 

[xena]

I've started suffering from chain slipping since recently putting a larger front chainring on my 11 speed 2018 Cube Reaction Race. It's only when i'm in 10th & 11th gear.

I went from the standard 12T chainring to a 15T to get a bit more top end speed, and fitted a new chain of the same size at the same time. It feels like its the front chainring thats slipping, but I can't be 100% certain.

What could be causing it?

I thought they are 15t standard up front? I've just bought an 18t for mine.

 

[soundwave]

I thought they are 15t standard up front? I've just bought an 18t for mine.

depends what sort of bike it is mine come with 16t but now run dual 18t and 20t

 

[xena]

depends what sort of bike it is mine come with 16t but now run dual 18t and 20t

I have the same bike as him

 

[soundwave]

the bosch sprocket sizes go from 13t to 20t there are bigger ones but pretty much pointless after 20t.

imo the 2 smallest sprockets are worn and slipping id find a cheaper cassette chain combo or get a cassette where you can buy the sprockets on there own and replace when needed.

 

[The Bear]

The chain slipping has only started since swapping to a larger front chainring, which is why I assumed this was the cause. I fitted a brand new chain at the same time. It wasn't slipping before this, but perhaps the two smallest rear cogs had already worn, but were nicely bedded in with the previous chain, but not with the new chain?

 

[The Bear]

imo the 2 smallest sprockets are worn and slipping id find a cheaper cassette chain combo or get a cassette where you can buy the sprockets on there own and replace when needed.

Maybe I will have to do this. However my bother paid good money for a cassette with separate individual sprockets, only to discover that the sprockets weren't available to purchase separately.

 

[chris_n]

The chain slipping has only started since swapping to a larger front chainring, which is why I assumed this was the cause. I fitted a brand new chain at the same time. It wasn't slipping before this, but perhaps the two smallest rear cogs had already worn, but were nicely bedded in with the previous chain, but not with the new chain?

It's the cassette, given you have changed the chainring because it's too low geared suggests you spend most of the time in the top couple of gears. As they have fewer teeth they will wear very quickly unless they are made of better material. Change the cassette sooner rather than later before it damages the new chain.

 

[soundwave]

chains wear with the cassette teeth so if you change the front sprocket and the chain for new ones the cassette teeth are still worn so the new chain will skip over the worn teeth as the chain wont be worn so wont grip the teeth of the cassette esp the smaller sprockets.

 

[The Bear]

I'll get the cassette changed.

The cassette that came with the bike is a Shimano SLX M7000 11-46T which typically costs about £60. When last changed I went for the same again. Are there any others that should be considering?

 

[xena]

I was only asking about the front chain ring, as if you have lengthened the chain, yet are still only running 15t up front, won't the chain be too long and may cause slippage in the smaller cogs?